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  • Types of Melasma: How They Differ and Why It Matters by Sarah Curran MSc

    Melasma is a common form of facial hyperpigmentation characterised by symmetrical, irregularly bordered patches of increased pigmentation. While it is often discussed as a single condition, melasma is clinically and histologically diverse. Understanding its different types is essential, as both the distribution of pigmentation and the depth of pigment within the skin significantly influence prognosis and treatment outcomes.

    Clinical Pattern: Where Melasma Appears

    Melasma is classified into distinct types based on its anatomical distribution on the body.

    Centrofacial Melasma

    This is the most common presentation. It typically involves the forehead, cheeks, nose, upper lip, and chin. Its widespread distribution across central facial features often makes it the most noticeable and cosmetically concerning type.

    Malar Melasma

    Malar melasma is more localised, affecting the cheeks and the nose. This pattern is frequently seen in individuals with sun exposure concentrated on the mid-face.

    Mandibular Melasma

    This type presents along the jawline and chin. It is more commonly observed in older individuals and is often associated with cumulative sun damage.

    Extrafacial Melasma

    A less common variant, extrafacial melasma affects areas beyond the face, including the neck, sternum, forearms, and upper chest. This type may be linked to chronic environmental exposure and, in some cases, hormonal influences.

    Depth of Pigment: Why It Matters

    Beyond location, melasma is further classified based on how deeply pigment is deposited within the skin. This classification is critical, as it directly impacts treatment responsiveness.

    Epidermal Melasma

    Pigment is located in the upper layers of the skin. It often appears more defined under Wood’s lamp examination and typically responds well to topical depigmenting agents.

    Dermal Melasma

    Pigment is located deeper in the dermis and involves pigment-containing cells known as melanophages. This type is more resistant to treatment and often slower to improve.

    Mixed Melasma

    Mixed melasma includes both epidermal and dermal pigment. It is common in clinical practice and shows variable response to treatment depending on the dominant component.

    Indeterminate Melasma

    In this type, the depth cannot be clearly classified. It is more common in darker skin types or complex presentations and requires careful clinical assessment.

    Diagnostic Tools and Their Role

    Accurate classification of melasma type relies on a combination of diagnostic techniques.

    Wood’s lamp examination helps differentiate between epidermal, dermal, mixed, and indeterminate types by enhancing pigment contrast.

    Dermoscopy allows visualisation of pigment patterns, colour variation, and network structures, which supports assessment of pigment depth.

    Reflectance confocal microscopy and photoacoustic microscopy provide high-resolution imaging to assess pigment depth and identify additional features such as vascular involvement.

    Emerging Insights: The Role of Vascular Changes

    Recent advances suggest that melasma is not solely a pigmentary disorder. Photoacoustic microscopy has introduced refined subtypes based on both pigment depth and vascular involvement.

    These include epidermal pigment only, epidermal pigment with vascular changes, mixed pigment, and mixed pigment with vascular involvement. Increased dermal blood vessels may contribute to the persistence of melasma and may influence treatment strategies in resistant cases.

    Why Correct Classification Is Essential

    Identifying the specific type of melasma has direct clinical relevance. It helps predict treatment response, guides therapy selection, supports realistic patient expectations, and informs long-term management planning.

    Take Home Message

    Melasma is a condition I see very frequently when doing facials and treatments and also teaching, and while it is medically benign, it can be really bothersome and distressing for many individuals due to its impact on facial appearance and confidence. It is a multifactorial and heterogeneous condition best understood through its clinical distribution and the depth of pigmentation. Clinical patterns include centrofacial, malar, mandibular, and extrafacial types. Histological classification includes epidermal, dermal, mixed, and indeterminate forms. Emerging imaging techniques add further refinement by identifying vascular involvement.

    Accurate classification is fundamental to optimising treatment outcomes and improving long-term management of this chronic and often recurrent condition.

    Medical Disclaimer

    This article is intended for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. Melasma is a complex dermatological condition, and individual cases may vary. Always consult a qualified healthcare professional or dermatologist for personalised assessment and treatment recommendations.

    Connect with Me

    For more evidence-based content on skin, health, and aesthetics, follow me on
    Instagram: sarahcurranfitpro

  • Getting Back on Track After Binge Eating: What Research Suggests

    Binge eating doesn’t just end when the episode finishes.

    For most people, what follows is the harder part. Guilt, frustration, and the urge to fix it quickly by eating less, training more, or starting over.

    The issue is that response is often what keeps the cycle going.

    Research consistently shows that what actually helps is not punishment. It is returning to structure, building better coping skills, and changing how you respond to yourself in that moment.

    This is something I come across regularly in my work. I recently completed a Level 9 in Behaviour Change in UCD, and binge and restrict patterns are one of the most common things I see with clients, be it general fat loss clients or athletes.

    It is also something I have experienced myself, particularly during periods of bodybuilding style training after a cut. When calories are low for a long time, both your body and your mindset are primed for a rebound.

    I see similar patterns in fighters as well, especially around weight cuts, where restriction followed by overeating can become very normalised.

    Something I would recommend for everyone is to not just plan for the restriction phase of their deficit, but also how they plan to come out of it and eat at maintenance again when it finishes.

    Why the all or nothing approach does not work

    After a binge, the instinct is usually to tighten everything up

    Eat less the next day
    Cut out certain foods
    Train harder

    It feels like discipline, but in reality it just sets up the next binge.

    You end up stuck in a loop of restriction, cravings, bingeing, guilt, then back to restriction.

    Breaking that cycle starts with doing the opposite of what your instinct is telling you.

    What to do in the next 24 hours

    Go back to regular eating

    One of the most important things you can do is return to normal meals and snacks.

    Not skipping meals. Not saving calories. Just eating in a structured, consistent way.

    This helps bring things back to baseline and reduces the chances of another binge.

    Do not try to undo it

    Extra training or cutting food to compensate might feel productive, but it reinforces the cycle.

    Your training should stay the same
    Structured
    Planned
    Not used as punishment

    You are not trying to erase anything. You are just getting back to your routine.

    Change how you speak to yourself

    This is a big one and it is backed by research.

    People who respond with more self compassion are less likely to binge again, feel less out of control, and handle setbacks better.

    That does not mean ignoring it. It means not attacking yourself over it.

    A simple shift can help
    That happened. I am getting back on track now.

    The bigger picture

    Binge eating is very closely linked to how people deal with emotions.

    Most binges do not come out of nowhere. They are usually preceded by stress, low mood, or feeling overwhelmed.

    Food becomes a quick way to switch off or escape, even if it is only temporary.

    Common patterns that make it worse are overthinking what happened, blaming yourself, thinking in extremes, and trying to ignore how you feel.

    These tend to increase the chances of it happening again.

    What helps is building better ways to respond in those moments

    Noticing what you are feeling without reacting straight away
    Allowing discomfort without trying to escape it immediately
    Stepping back from all or nothing thoughts
    Having alternative actions ready

    These are skills and they improve with practice.

    Approaches that work

    Different approaches tend to come back to similar principles.

    CBT style approaches focus on getting eating patterns consistent, identifying triggers, challenging unhelpful thoughts, and having a plan for setbacks.

    DBT style approaches focus more on handling intense emotions, managing urges, and staying present instead of reacting.

    Self compassion and mindfulness help reduce harsh self criticism, shame, and automatic reactions. Even short interventions can make a noticeable difference.

    Structured training can help, but only when it is not used as a way to compensate. It should support your routine, not punish you for going off track.

    For athletes and high performers

    This tends to come up more in people who are disciplined and goal driven.

    Whether it is bodybuilding, fighters making weight, or people holding themselves to high standards, there is often pressure to stay lean, rigid rules around food, and an all or nothing mindset.

    After a binge, the focus should stay simple

    Eat normally
    Train as planned
    Do not compensate

    Longer term, it helps to shift focus from appearance to performance, be aware of high risk periods like cuts or stress, and build more flexibility into your approach.

    One of the biggest drivers here is self critical thinking.

    That voice that says that was not good enough is often the same one driving both restriction and bingeing.

    It is something I see constantly in both clients and athletes.

    Take home message

    Getting back on track after a binge is not about being stricter.

    It is about returning to structure, staying consistent, managing emotions better, and dropping the self criticism.

    Long term progress comes from responding better, not reacting harder. Having a plan in place for after any kind of cut can really help, and the most important thing is to give yourself grace.

    Disclaimer

    This article is for educational purposes only and is not a substitute for individual medical or psychological advice. If you are experiencing frequent binge eating or feel out of control around food, it is important to seek support from a qualified professional.

    For more evidence based coaching and education, you can find me on Instagram at @sarahcurranfitpro.

  • Cryptochromes in the Hair Follicle: Blue Light, CRY1, and Hair Growth by Sarah Curran MSc

    When we think about hair growth, most people jump straight to nutrition, hormones, or topical treatments. But there is a really interesting and still emerging area of research looking at how light, specifically blue light, interacts with proteins in the hair follicle to influence growth.

    This actually came up in tonight’s skin science lecture, and it is one of those topics that really sticks with you because it links together so many areas we do not always think about, including light exposure, cellular biology, and hair growth.

    At the centre of this is cryptochrome 1 (CRY1), a blue light sensitive protein traditionally known for its role in circadian rhythms. Recent dermatology research now shows that CRY1 is not only present in human hair follicles, but may actively regulate the hair growth cycle.

    What Are Cryptochromes?

    Cryptochromes are proteins that respond to blue light and help regulate the body’s internal clock. They have been studied for years in relation to sleep, metabolism, and cellular timing.

    What is newer, and particularly relevant for us in aesthetics, skin, and hair science, is that these same proteins are active in the skin and hair follicles, where they appear to influence cell behaviour, growth, and regeneration.

    CRY1 in the Hair Follicle

    CRY1 is strongly expressed in anagen, the active growth phase of the hair cycle. It has been identified in key areas of the follicle, including:

    • Epithelial stem cell regions
    • Outer root sheath (ORS) keratinocytes

    These are critical zones that drive hair growth. So when a protein is highly active here, it is likely playing a functional role.

    How Blue Light Influences Hair Growth

    Research using 453 nm blue light, a specific wavelength, has shown some really interesting effects on hair follicle biology:

    • Increased CRY1 protein levels in keratinocytes and whole follicles
    • Prolongation of the anagen growth phase
    • Delayed transition into catagen, the regression phase
    • Increased metabolic activity and proliferation in ORS cells at low doses

    In simple terms, low dose blue light appears to support hair staying in the growth phase for longer.

    CRY1 and Hair Cycle Control

    When researchers manipulate CRY1 directly, the effects become even clearer.

    Silencing CRY1 leads to:

    • Earlier transition into catagen
    • Reduced cell proliferation

    Activating CRY1 using compounds like KL001 leads to:

    • Prolonged anagen phase
    • Increased expression of growth related genes

    CRY1 also appears to regulate genes involved in:

    • Cell cycle progression, for example CDK6
    • Apoptosis, or programmed cell death

    This supports the idea that CRY1 helps maintain a pro growth, anti regression environment within the follicle.

    It Is Not Working Alone: OPN3 and Light Signalling

    CRY1 does not act in isolation. Another protein called OPN3, a blue to green light sensitive opsin, is also involved.

    Both CRY1 and OPN3 are expressed in ORS cells, and research shows:

    • Knocking down either protein reduces cell proliferation
    • Both are required for the full effect of blue light on hair growth

    This suggests a coordinated light sensing system within the follicle, where multiple photoreceptors work together to influence growth and cell behaviour.

    The Circadian Connection

    One of the most interesting aspects of CRY1 is its link to the circadian rhythm.

    Hair follicles appear to have their own clock system, involving genes like:

    • BMAL1
    • CLOCK
    • PER1
    • CRY1

    These genes oscillate over a 24 hour cycle and are linked to:

    • Timing of the hair growth phase
    • Stem cell activity
    • Cellular turnover

    There is also evidence from animal models, such as seasonal hair growth in goats, showing that light exposure and photoperiod can influence hair cycling via these clock genes.

    So this is not just about light hitting the skin. It is about light acting as a timing signal for hair growth itself.

    What This Means for Treatments

    From a practical perspective, this research opens the door to light based therapies for hair growth.

    The key takeaways so far:

    • Low dose blue light may enhance hair growth by increasing CRY1 activity
    • CRY1 supports the anagen phase and reduces premature regression
    • There is a clear biological mechanism, not just a cosmetic effect

    However, this is important. Most of the current evidence comes from:

    • In vitro, cell based studies
    • Ex vivo, isolated human follicle models

    We still need well designed human clinical trials to determine:

    • Optimal wavelengths and dosages
    • Safety over long term use
    • Real world effectiveness

    Take Home Message

    CRY1 is emerging as a key regulator in hair follicle biology, linking light exposure, circadian rhythms, and hair growth.

    The current evidence suggests:

    • CRY1 is highly active in growing hair follicles
    • Blue light at 453 nm increases CRY1 levels
    • This helps prolong the growth phase and support proliferation
    • CRY1 works alongside other photoreceptors like OPN3
    • Light based therapies show potential but are not fully clinically established yet

    From my perspective, this is a great example of where lifestyle, environment, and cellular biology all intersect. It also reinforces something I always come back to. Small, often overlooked factors like light exposure can have a much bigger impact on the body than we realise.

    And as always, the key is staying evidence based while keeping an open mind as the research evolves.

    Medical Disclaimer

    This article is for educational purposes only and is based on current research evidence. It is not intended to replace medical advice, diagnosis, or treatment. If you are experiencing hair loss or any scalp condition, you should consult with a qualified healthcare professional or dermatologist before starting any new treatment, including light based therapies.

  • Ultraviolet Light and Skin Aging: What’s Really Happening Beneath the Surface by Sarah Curran MSc

    One of the most important topics we are covering in skin science is the impact of UV rays on the skin. When we talk about skin aging, most people think of time as the main driver. In reality, ultraviolet (UV) exposure is the dominant external factor, responsible for up to 90 percent of visible skin aging in exposed areas.

    This is where the concept of photoaging comes in. Photoaging refers to premature aging caused by chronic sun exposure. While intrinsic or chronological aging is inevitable, UV exposure significantly accelerates and amplifies these changes.

    Photoaging vs Normal Aging

    Intrinsic aging is driven by genetics and time. It leads to gradual thinning of the skin, fine lines, and reduced elasticity.

    Photoaging is externally driven and largely preventable. It overlaps with intrinsic aging but progresses faster and presents differently. Common features include deeper wrinkles, skin laxity, uneven pigmentation, rough texture, and visible blood vessels known as telangiectasias.

    In simple terms, sun exposure does not just age the skin, it changes how the skin ages.

    UVA vs UVB: Not All UV Is Equal

    Understanding the difference between UVA and UVB is essential when it comes to prevention.

    UVA, which ranges from 320 to 400 nanometres, makes up about 95 percent of the UV radiation that reaches the earth. It penetrates deeply into the dermis and is primarily responsible for collagen breakdown, pigmentation changes, and deep wrinkle formation. UVA is present all day, all year, and can pass through clouds and glass.

    UVB, which ranges from 280 to 320 nanometres, has higher energy but mainly affects the epidermis. It is responsible for sunburn, direct DNA damage, and mutations associated with skin cancer.

    Both contribute to skin aging, but UVA is the main driver of long-term structural damage, while UVB is the primary cause of acute injury.

    The Biological Mechanisms Behind Skin Aging

    UV radiation accelerates skin aging through several interconnected biological pathways.

    DNA damage is one of the primary mechanisms. UV exposure leads to the formation of DNA lesions such as cyclobutane pyrimidine dimers and 8-oxoG. This results in cellular dysfunction, mutations, and an increased risk of carcinogenesis.

    Oxidative stress also plays a major role. UV exposure generates reactive oxygen species that damage lipids, proteins, and DNA. This oxidative damage contributes significantly to visible aging.

    Collagen breakdown and extracellular matrix degradation occur as UV exposure increases matrix metalloproteinases and reduces TGF beta signalling. This leads to collagen degradation, loss of elasticity, and thinning of the dermis, which presents clinically as wrinkles and sagging.

    Cellular senescence and inflammation are also key contributors. Damaged cells enter a senescent state and release inflammatory signals known as the senescence associated secretory phenotype. This drives chronic low grade inflammation, often referred to as inflammaging.

    UV exposure also alters immune function. It suppresses normal immune responses in the skin, reducing repair capacity and increasing susceptibility to skin cancer.

    Clinical Presentation of Photoaging

    Over time, cumulative UV exposure leads to a range of visible skin changes. These include fine and deep wrinkles, dryness, rough texture, skin laxity, pigmentation changes, telangiectasias, elastosis, and slower wound healing.

    It is important to recognise that damage begins long before it becomes visible on the skin.

    Skin Type and UV Vulnerability

    Skin response to UV exposure varies depending on skin type.

    Lighter skin types, classified as Fitzpatrick I to III, have much lower intrinsic protection, with an approximate SPF of 3.3. This makes them more vulnerable to UV induced DNA and collagen damage.

    Darker skin types have higher intrinsic protection, with an approximate SPF of 13.4. However, they are more prone to pigmentation issues and skin cancers are often detected later.

    UVA plays a particularly important role in pigmentary aging, especially in individuals with darker skin tones.

    Why Sunburn Matters

    Sunburn is more than temporary redness. It is a clear indicator of significant biological damage.

    Frequent sunburns are strongly associated with increased skin cancer risk. Studies show that repeated sunburns can increase melanoma and squamous cell carcinoma risk by around 50 percent or more. Childhood sunburn is particularly significant, and repeated episodes can double the risk of basal cell carcinoma.

    Sunburn also causes immediate tissue and immune damage. It is an acute inflammatory response characterised by redness, pain, and swelling. DNA damage begins within hours, and immune suppression occurs at the level of the skin.

    Repeated sunburn accelerates visible aging by contributing to wrinkles, pigmentation changes, and structural skin damage. It is also important to note that significant damage can occur even without visible sunburn.

    Prevention: The Most Effective Anti Aging Strategy

    If UV exposure is the primary driver of skin aging, then protection becomes the most effective intervention.

    Limiting exposure and seeking shade is the first step. It is recommended to avoid peak UV times, particularly around midday and when the UV index is three or higher.

    Physical barriers such as clothing, hats, and sunglasses are highly effective. UPF clothing, long sleeves, wide brimmed hats, and UV blocking sunglasses significantly reduce UV exposure.

    Daily use of broad spectrum sunscreen is essential. A minimum of SPF 30 is recommended, with SPF 50 or higher advised for higher risk individuals. Sunscreen should protect against both UVA and UVB, be applied adequately, and reapplied every two hours or after swimming or sweating. Regular use has been shown to reduce photoaging, DNA damage, and skin cancer risk.

    It is also important to consider factors beyond UV. Visible light and pollution contribute to pigmentation and oxidative stress. Tinted sunscreens containing iron oxides and the use of antioxidants such as vitamins C and E or plant compounds can provide additional protection.

    Emerging Areas in Skin Protection

    Ongoing research is exploring strategies to mitigate UV induced damage. These include enhancing DNA repair pathways, supporting autophagy, and the use of compounds such as retinoids, metformin, and plant derived antioxidants.

    While these approaches are promising, UV protection remains the most effective and accessible strategy.

    Final Takeaway

    Ultraviolet radiation is the single most significant external driver of premature skin aging. It accelerates aging through DNA damage, oxidative stress, inflammation, and collagen breakdown.

    Protecting the skin from UV exposure is the most effective step you can take to preserve skin health, maintain appearance, and support long term skin function.

    Disclaimer

    This article is for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional or dermatologist for individual concerns or conditions related to your skin.

    Follow for More Evidence Based Content

    For more evidence-based guidance on skin health, nutrition, and fitness, follow me on Instagram @sarahcurranfitpro where I share practical, science-backed advice you can actually apply.

  • Skin Infections in Combat Sports: Evidence-Based Strategies to Reduce Risk by Sarah Curran MSc

    Skin infections remain one of the most common and disruptive issues in combat and contact sports, including wrestling, Brazilian jiu-jitsu, judo, MMA, and rugby. These environments create ideal conditions for the transmission of bacterial, fungal, and viral pathogens, often leading to missed training, withdrawal from competition, and wider team outbreaks. I covered the microbiome of the skin recently in my skin science course, and it is really relevant to combat sports due to the prevalence of skin infections in this area.

    Current research consistently highlights that while the risk cant be eliminated, it can be significantly reduced through structured hygiene practices, early detection, and coordinated team protocols.

    Infection Risk in Combat Sports

    The high incidence of skin infections in combat athletes is multifactorial. Key contributing factors include:

    • Repeated skin-to-skin contact
    • Frequent abrasions, cuts, and mat burns
    • Sweat accumulation and friction, particularly in occluded areas
    • Use of shared equipment and facilities

    Additionally, a proportion of athletes may carry organisms such as Staphylococcus aureus asymptomatically, increasing the potential for silent transmission within teams.

    Most Common Infections

    Across the literature, three categories dominate:

    • Bacterial: Methicillin-resistant Staphylococcus aureus (MRSA) and other Staphylococcal infections
    • Fungal: Tinea corporis (ringworm)
    • Viral: Herpes gladiatorum

    These infections are highly transmissible in contact settings and can escalate quickly if not identified and managed early.

    Core Prevention Strategies

    Evidence supports a multi-layered approach to infection control. No single intervention is sufficient in isolation, and consistent implementation across several domains is required.

    Personal Hygiene

    • Shower immediately after training or competition
    • Maintain regular hand hygiene
    • Keep fingernails short
    • Avoid sharing personal items such as towels, razors, clothing, or water bottles

    Clothing, towels, and training gear should be washed in hot water at or above 50°C, and athletes should change out of sweat-soaked clothing promptly.

    Wound Management

    • Clean all cuts, abrasions, and mat burns immediately
    • Cover wounds appropriately during training
    • Monitor for early signs of infection

    Athletes with suspicious lesions should be removed from contact activity until assessed and no longer considered contagious.

    Environmental Hygiene

    • Implement structured cleaning protocols for mats and equipment
    • Regularly disinfect shared spaces including showers and changing areas
    • Use effective disinfectants with residual activity where possible

    Research shows that appropriate mat disinfection and hand hygiene measures can significantly reduce microbial load.

    Screening and Early Intervention

    • Routine skin checks, particularly before competition
    • Early reporting of suspicious lesions
    • Prompt isolation of affected athletes

    This is critical in preventing isolated infections from developing into outbreaks.

    Education and Protocols

    Education is consistently identified as a key factor in reducing infection rates. Athletes and staff should understand:

    • How to recognize common infections
    • The importance of hygiene and wound care
    • When to seek assessment and temporarily withdraw from training

    Clear, enforceable hygiene protocols within teams are essential.

    The Skin Microbiome and Infection Risk

    From a skin science perspective, the skin microbiome is highly relevant. There is a growing body of research showing its role in infection susceptibility and spread in combat sports.

    In athletes, particularly those in contact sports, the microbiome is constantly challenged by sweat, friction, frequent washing, antiseptic use, and shared environments. This can lead to microbial imbalance or dysbiosis, where protective organisms are reduced and opportunistic pathogens become more dominant.

    Research shows that combat sport athletes often have altered microbial profiles compared to non-athletes, and dysbiosis is associated with increased susceptibility to bacterial, fungal, and viral infections. Disruption of the skin barrier alongside microbiome imbalance facilitates pathogen entry and transmission. While hygiene is essential, overly aggressive or excessive use of antiseptics may further disrupt this balance.

    A balanced approach is recommended:

    • Effective hygiene practices
    • Protection of skin integrity
    • Avoidance of unnecessary overuse of harsh antimicrobial products

    Additional Considerations

    • Rapid weight loss practices may influence infection management
    • In high-risk settings, prophylactic antiviral or antifungal strategies may be considered
    • MRSA colonization may occur in asymptomatic athletes, and outbreak management may include screening and targeted decolonization under medical guidance

    Take-Home Message

    Combat sport athletes are at elevated risk of skin infections, but consistent and structured hygiene practices, proper wound care, environmental cleaning, routine screening, and ongoing education significantly reduce risk. Protecting the skin microbiome and barrier integrity while using antiseptics strategically further supports long-term skin health and infection prevention.

    Medical Disclaimer

    This article is for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment. Athletes presenting with suspected skin infections should seek assessment from a qualified healthcare professional and follow sport-specific medical guidelines before returning to training or competition.

  • Evidence-Based Supplements for Combat Sports Performance by Sarah Curran MSc

    Combat sports place unique physiological demands on athletes, requiring a combination of power, endurance, repeated high-intensity efforts, and technical precision. Across the literature, a small group of supplements consistently demonstrates performance benefits. The most well-supported include caffeine, creatine, sodium bicarbonate, and β-alanine, with emerging evidence for beetroot juice. A well-structured, high-quality diet should always form the foundation of performance, with supplements used as a secondary strategy to provide a potential edge.

    Core Performance Supplements

    Caffeine -The Strongest Evidence Base

    Caffeine is the most consistently supported ergogenic aid in combat sports. Multiple systematic reviews and meta-analyses show that doses of approximately 3–5 mg/kg taken 30–60 minutes before competition improve combat-specific performance.

    These improvements include increased number of attacks and throws, enhanced handgrip strength, faster reaction time, greater power output, and improved time to exhaustion. Caffeine enhances glycolytic energy contribution and increases lactate tolerance.

    Research also shows small but clear improvements in handgrip strength and total judo throws, alongside increases in blood lactate and heart rate without a corresponding rise in perceived exertion. A network meta-analysis ranks caffeine, as well as caffeine combined with sodium bicarbonate, among the most effective supplements for improving power and technical actions such as kicks and throws in elite athletes.

    In taekwondo-specific research, doses of 3–5 mg/kg have been shown to acutely improve both physical performance and psychological state. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect.

    Creatine

    Creatine is well established for improving mean and peak power in combat-specific tests. Evidence from network meta-analyses shows that creatine, particularly when combined with sodium bicarbonate, produces large improvements in power output compared to placebo.

    Combat-sport-specific reviews demonstrate that creatine supplementation increases body mass, fat-free mass, maximal strength, and power. However, it has little effect on sport-specific endurance or fatigue. Importantly, creatine has a strong safety profile.

    Sodium Bicarbonate and Buffering Agents

    Sodium bicarbonate is a key buffering agent shown to improve repeated high-intensity efforts and glycolytic capacity across combat sports including judo, taekwondo, karate, wrestling, jiu-jitsu, and boxing.

    Both acute and chronic supplementation strategies have demonstrated benefits, particularly during later stages of competition when acidosis and fatigue accumulate. Sodium bicarbonate is often most effective in improving performance late in matches.

    β-alanine, another buffering-related supplement, increases intramuscular carnosine levels. This contributes to improvements in strength, power, and total work during high-intensity efforts in combat sports.

    Beetroot (Dietary Nitrate)

    Beetroot supplementation, a source of dietary nitrate, may enhance oxidative metabolism and improve isometric and isokinetic force, as well as balance. These adaptations are particularly relevant for grappling-based sports.

    However, results are variable and appear to depend on dosage, muscle group involved, and specific supplementation protocols. While promising, the current evidence base remains limited compared to core supplements.

    Micronutrient Support

    Position stands recommend the use of a daily multivitamin, vitamin D, omega-3 fatty acids, and minerals such as iron and zinc when required. These support overall health, recovery, and brain function alongside performance-focused supplementation.

    Practical Considerations

    You do not need to spend a fortune on supplements or buy into expensive, heavily marketed brands. Cheaper brands can be just as effective, as higher costs often reflect marketing rather than product quality.

    Where possible, choose supplements that are third-party tested. This is particularly important for athletes competing in tested federations, as contamination with banned substances can occur and may lead to a failed drug test.

    Summary of Supplement Use by Performance Goal

    Acute competition performance:
    Caffeine, sodium bicarbonate, β-alanine

    Power, strength, and fat-free mass during training camp:
    Creatine, β-alanine

    Repeated high-intensity efforts:
    Sodium bicarbonate, β-alanine, caffeine

    Aerobic capacity and balance:
    Beetroot

    Take home message

    Across combat sports, the most robust evidence supports the use of caffeine, creatine, sodium bicarbonate, and β-alanine for enhancing performance. Beetroot juice shows emerging potential as an additional strategy. A strong nutritional foundation should always come first, with supplements used strategically to provide a potential performance advantage.

    Supplement choice and dosing should be individualised, tested during training, and implemented alongside a well-structured nutrition and weight management plan.

    Follow @sarahcurranfitpro on Instagram for more evidence-based content on performance, nutrition, and health.

    Medical Disclaimer

    This article is for educational purposes only and is not intended as medical advice. Supplements may not be suitable for all individuals and can interact with medications or underlying health conditions. Always consult a qualified healthcare professional before starting any supplementation protocol.

  • Sodium Bicarbonate in Combat Sports: Benefits, Mechanisms, and Practical Use by Sarah Curran MSc Exercise and Nutrition

    Sodium bicarbonate, commonly known as baking soda, is one of the most well researched legal ergogenic aids for high intensity, intermittent exercise. This makes it especially relevant for combat sports, where performance depends on repeated bursts of explosive effort.

    Physiological Rationale

    High intensity exchanges in boxing, MMA, judo, wrestling, taekwondo, and karate rely heavily on anaerobic glycolysis. This process rapidly produces hydrogen ions, which lowers muscle and blood pH. The resulting acidosis contributes to fatigue and reduces force production.

    Supplementing with sodium bicarbonate increases blood bicarbonate levels and raises pH. This improves the body’s buffering capacity outside the muscle, helping remove hydrogen ions more efficiently. As a result, athletes can sustain higher intensity efforts and tolerate greater lactate accumulation before performance declines.

    Research consistently shows performance benefits in activities lasting approximately 30 seconds to 12 minutes. This includes repeated sprint work, cycling tests, and sport specific protocols that closely reflect combat rounds.

    Performance Benefits in Combat Sports

    Research in combat athletes shows that sodium bicarbonate can improve several aspects of performance.

    Athletes are able to sustain high intensity efforts for longer. In simulated taekwondo, supplementation increased glycolytic energy contribution in the first round and significantly increased total attack time across multiple rounds.

    Performance improvements are often more noticeable as fatigue builds. This is particularly relevant in sports like judo, boxing, and wrestling, where later rounds or repeated bouts place a high demand on buffering capacity.

    Studies also show increases in total work and power output. These improvements may be even greater when sodium bicarbonate is combined with creatine, particularly for explosive exchanges.

    There is also evidence for improved recovery between bouts. In elite boxing, athletes who consumed sodium bicarbonate after an intense effort showed faster recovery of acid base balance and improved performance in a subsequent bout.

    The main benefit appears to be in muscular endurance rather than maximal strength. Athletes can perform more repetitions or sustain effort longer, which aligns with the repeated high intensity nature of striking and grappling.

    Evidence from Broader High Intensity Sport

    Position stands from leading sports nutrition bodies conclude that sodium bicarbonate improves performance in high intensity efforts across a range of sports. These include cycling, running, swimming, and rowing.

    The greatest benefits are seen in efforts lasting from around 30 seconds to 12 minutes, as well as repeated high intensity bouts. These time frames closely match the demands of most combat sports, where rounds typically last between two and five minutes with short recovery periods.

    Practical Application for Combat Athletes

    Dosing and Timing

    Effective dosing is well established.

    A minimum effective dose is around 0.2 grams per kilogram of body weight. For most athletes, 0.3 grams per kilogram appears to provide the best balance between effectiveness and tolerability.

    Timing is important. Sodium bicarbonate should generally be taken between 60 and 180 minutes before training or competition to align with peak blood bicarbonate levels. However, individual responses vary, so testing in advance is essential.

    Some athletes may benefit from a multi day loading strategy. This typically involves 0.4 to 0.5 grams per kilogram per day, split into smaller doses over three to seven days before competition. This approach may improve buffering capacity while reducing the risk of gastrointestinal discomfort on the day.

    There is also emerging evidence for using sodium bicarbonate after an initial bout or training session. This may help speed up recovery and improve performance in subsequent efforts, which is particularly useful in tournaments or double session days.

    For weight class athletes, the sodium content should be considered carefully, especially in relation to fluid balance and weight cutting strategies.

    Best Situations to Use It

    Sodium bicarbonate is most useful in scenarios that involve repeated high intensity efforts.

    This includes hard sparring sessions with multiple rounds, high pace pad or bag work with short rest periods, and grappling sessions that involve continuous exchanges.

    It is also beneficial during conditioning sessions that use intervals ranging from around 30 seconds to four minutes, particularly when rest periods are short.

    Athletes competing in tournaments with multiple bouts in one day may benefit from both pre event and post bout strategies.

    It is less useful for maximal strength work, where fatigue from acidosis is not a primary limiting factor.

    Side Effects and How to Minimise Them

    The most common side effects are gastrointestinal. These include bloating, nausea, stomach pain, and in some cases vomiting. The likelihood of these symptoms increases with larger single doses.

    However, tolerance varies significantly between individuals.

    Several strategies can help reduce the risk of side effects.

    Using moderate doses between 0.2 and 0.3 grams per kilogram is often better tolerated than larger doses.

    Taking sodium bicarbonate around three hours before exercise may reduce symptoms compared to shorter timing windows.

    Consuming it alongside a carbohydrate rich meal can also improve tolerance.

    Enteric coated capsules may help reduce gastrointestinal discomfort by delaying release until the intestines.

    Most importantly, athletes should trial their strategy well in advance of competition to find what works best for them.

    Combining with Other Supplements

    There is some evidence that sodium bicarbonate can have additive effects when combined with other supplements.

    Creatine appears to enhance improvements in power output, particularly during repeated explosive efforts.

    Beta alanine, another buffering agent, may provide additional benefits when used alongside sodium bicarbonate, although research in combat athletes is still limited.

    The evidence for combining sodium bicarbonate with caffeine or nitrates is less clear, although there is some potential based on broader sports nutrition research.

    Practical Considerations and Real World Use

    One of the biggest advantages of sodium bicarbonate is how accessible and inexpensive it is compared to many other supplements on the market. It is a very cheap way to potentially improve performance, yet it remains surprisingly underused in combat sports. Despite being consistently included in sports nutrition guidelines, it is not something widely seen in practice, especially compared to more popular supplements like pre workouts or fat burners.

    To put that into perspective, I checked the price today in Aldi and it is literally 59 cent. That is probably one of the cheapest performance aids you will come across, which makes it even more surprising that more athletes are not using it. This may come down to concerns around side effects or simply not knowing how to use it properly.

    It is important that sodium bicarbonate is not introduced for the first time in the week of a fight. Like any performance strategy, it should be trialled earlier in a training block to assess individual tolerance and effectiveness. Starting with lower doses is a sensible approach, gradually building up as needed. While responses can vary, the overall body of evidence is strong and supports its use as a practical and effective tool for improving high intensity performance in combat sports.

    Limitations and Research Gaps

    Despite strong physiological support and many positive findings, some limitations remain.

    Not all studies show performance improvements, even when changes in blood pH are observed. This highlights the importance of individual response and the specific demands of the test or sport.

    There is also limited research in female combat athletes, although existing data suggests similar benefits.

    More sport specific studies are needed, particularly those that replicate real fight conditions, including scoring, pacing, and tactical elements.

    Long term research is also lacking, especially regarding how regular use may influence training adaptations over time.

    Take Home Message

    Sodium bicarbonate is a well supported and practical ergogenic aid for combat athletes when used correctly. By improving the body’s ability to buffer acidity, it allows athletes to maintain higher intensity efforts, delay fatigue, and perform more consistently across rounds and repeated bouts.

    It is also one of the most cost effective performance strategies available, yet remains underused. When trialled properly in training and tailored to the individual, it can offer a simple but meaningful edge in high intensity combat sport performance.

    Medical Disclaimer

    This article is for educational purposes only and is not intended as medical advice. Individuals should consult with a qualified healthcare professional or sports nutritionist before starting any supplementation protocol, particularly if they have underlying medical conditions, are taking medication, or are preparing for competition. Responses to sodium bicarbonate can vary, and appropriate dosing, timing, and tolerance should be assessed on an individual basis.

  • Weight Cutting for Female Fighters: Safer, Evidence-Based Guidelines by Sarah Curran MSc

    Weight Cutting for Female Fighters: Safer, Evidence-Based Guidelines by Sarah Curran MSc

    As someone who has spent years studying Exercise and Nutrition, and having done my MSc research project on weight cutting in combat sports, and completing the UFC Level 3 Specialist Sports Nutrition course, this is an area I’ve spent a lot of time on. I also love Muay Thai, and performance nutrition has always been a huge interest of mine, so this is something I care about both from a research and real-world perspective.

    Weight cutting is part of the sport. That’s just the reality of it. But how you approach it can make a huge difference to how you feel, how you perform, and how repeatable it is across a season.

    What Female Fighters Actually Do

    Weight cutting is extremely common across combat sports, with around 80–90% of female fighters doing it, often multiple times per year. The most common methods you’ll see, both in research and in real life, are dieting during camp, increasing training volume, using saunas or hot baths, and manipulating fluids in the final days. Professional fighters tend to push things further than amateurs.

    At higher levels, female fighters typically lose around 4.5–6.6% of their body mass in the final 72 hours before weigh-in. That is fairly consistent across weight classes. Where problems start to show up is when cuts go beyond about 5% in the last 24 hours, which is where you tend to see more fatigue, poorer performance, and higher injury risk.

    How Weight Cutting Is Usually Structured

    Most cuts follow a similar pattern, whether they are planned well or not. During the fight camp phase, the majority of the work should be done through a small calorie deficit, structured nutrition, and enough protein to preserve muscle and training quality. In the final 7–14 days, food gets a bit more controlled, training remains high, and some fighters start adjusting fluids. This is also where fatigue can creep in if things are not planned properly.

    In the final 24–72 hours, acute strategies come into play. When done correctly, this is not about starving yourself, it is about shifting body content. Common strategies include water loading then pulling it back, reducing sodium, dropping carbs and fibre, and using sauna or hot baths to sweat. These can work well when controlled and not overdone.

    Extreme methods such as laxatives, diuretics, vomiting, or diet pills still happen, especially at higher levels, but they increase risk without real performance benefit. These are methods to avoid from a coaching and evidence perspective.

    A More Structured, Evidence-Based Approach

    The goal is not to avoid weight cutting completely, it is to make it more controlled and predictable. Research supports keeping total loss in the final week to around 5% or less, avoiding going over that in the last 24 hours, and doing most of the work over 8–12 weeks during camp.

    From a nutrition side, aim for protein around 1.2–2.0 g/kg to hold onto muscle, carbohydrates around 3–4 g/kg to keep training quality high, and fats at 0.5–1 g/kg to support overall function. Nothing extreme, just structured.

    Using Carbohydrate and Fibre Reduction Properly

    This is one of the most useful tools in fight week when done right. Dropping carbohydrates reduces glycogen stores, and because glycogen holds water, body weight comes down without relying on dehydration. Reducing fibre lowers gut content. A low-residue approach in the final few days can make a real difference, accounting for around 1–2% of body weight. It is practical and generally well-tolerated short-term.

    Water Retention and Female Athletes

    Water retention in women is shaped by both menstrual hormones and deliberate fluid manipulation for weight cutting. Average shifts across the cycle are modest, but for some individuals, they can be meaningful, especially when combined with acute cuts.

    Estrogen and progesterone influence vasopressin and aldosterone, but for most women, overall fluid retention, plasma volume, and sweat losses change very little across the cycle. Some women see small increases in body weight of approximately 0.3–0.5 kg and extracellular fluid around menstruation or the luteal phase. MRI studies show calf muscle edema in some women during the menstrual phase, which can reduce agility if edema is noticeable.

    During the late follicular phase, heat dissipation may be slightly improved, with no consistent extra edema. In the mid to late luteal phase, fluid retention increases slightly and may shift to extracellular space, leaving some women feeling “puffy” with a slight weight increase. During menstruation, small body weight increases occur in some women along with localized edema, which can slightly reduce agility.

    Rapid cuts of 5–6% body mass in a few days rely almost entirely on body water loss, mainly extracellular water and plasma volume. This hypohydration can impair repeat-effort performance and heart-rate recovery if not carefully planned. Position stands recommend controlled acute water loss of 2–4% in 24 hours with structured rehydration and sodium replacement after weigh-in. Women should be cautious with water loading plus sodium restriction around the luteal phase, as higher hormone levels and naturally higher total body water may increase hyponatremia risk.

    Practical tips include expecting 0.3–0.7 kg “hormonal water” swings during menstruation or luteal phase. For tight weight cuts, this can be the difference between making weight or not, so track your cycle and daily weight trends. When using water loading or sauna, avoid overdrinking with low sodium, particularly in the luteal phase, and prioritize structured rehydration after weigh-in with oral solutions containing sodium at 125–150% of fluid lost.

    Menstrual Cycle, Hormones, and Weight Cutting

    The menstrual cycle itself has small and inconsistent effects on objective performance, but symptoms and perceived effort can vary noticeably. Many women feel worse during early follicular (menstrual) and late luteal phases. The bigger risk comes from aggressive or repeated weight cutting combined with low energy availability. This can lead to menstrual disruption, suppressed ovarian hormones, changes in stress hormones like cortisol, and reduced recovery, bone health, and overall performance. Tracking your cycle, symptoms, and weight-cut responses can help guide safer, more effective planning.

    Practical Takeaways

    The most effective approach is usually the least extreme:

    • Do most of the work during camp
    • Use carbohydrate and fibre reduction strategically in fight week
    • Keep acute cuts within a manageable range
    • Avoid high-risk methods like diuretics and laxatives
    • Take recovery seriously after weigh-in
    • Track your cycle, symptoms, and water retention to understand what feels best for you

    Take-Home Message

    Weight cutting is not going anywhere in combat sports, but the way it is done makes all the difference.

    A structured approach built around gradual fat loss, with smart use of fight-week strategies like carbohydrate and fibre reduction, careful acute water manipulation, and evidence-based rehydration, is the safest way to make weight while maintaining performance.

    For female fighters, understanding your cycle, tracking symptoms, and avoiding aggressive or repeated cuts is key. The goal is not just to make weight once, it is to do it safely, effectively, and consistently every time you step into the ring.

    Disclaimer: This information is for educational purposes only. Consult a qualified professional before making changes to your weight, nutrition, or training. Safety should always come first.

  • Why Unsafe Weight-Cutting Practices Persist in Combat Sports by Sarah Curran MSc

    In combat sports, whether boxing, MMA, wrestling, or Muay Thai, making weight is a central part of competition. Fighters often face intense pressure to drop to a lower weight class before a fight, and unfortunately, some methods used are extreme and unsafe. As someone who works in nutrition and has spent years researching exercise and performance during my MSc, I see these practices far too often, and the risks are very dangerous.

    Tradition and Culture Influence Methods

    Across combat sports, coaches and gyms rely on long-standing traditions. Fighters often learn to cut weight the same way their coaches did, believing that “this is how it’s done.” These practices can include excessive sauna use, wearing sweat suits, fluid restriction, or very low-calorie diets in the days before a fight.

    Through my experience in research and nutrition, I’ve observed that cultural norms frequently override evidence-based approaches. Even when safer, science-backed strategies exist, fighters are often encouraged to stick to older methods that may be risky.

    Short-Term Gains vs. Long-Term Health

    Rapid weight-cutting is often seen as a competitive advantage. Dropping several kilograms in the days before a weigh-in allows a fighter to face lighter opponents. But the focus on short-term performance comes at a cost.

    Extreme methods like dehydration, fluid restriction, excessive cardio, or vomiting can quickly reduce body weight but increase the risk of dizziness, fainting, kidney stress, cognitive impairment, and cardiovascular complications. In my nutrition work, I have seen fighters take days to fully recover after these extreme cuts, which can also negatively impact in-ring performance.

    Safe Strategies for Making Weight

    When weight has already been reduced gradually in the weeks prior through structured fat loss, simple, strategic manipulations of water balance can help fighters make weight safely. These include:

    • Reducing carbohydrate intake slightly, which temporarily lowers water stored in muscles and liver
    • Reducing dietary fibre, which can reduce gut content and improve the scale weight
    • Reducing sodium intake, which can help manage extracellular fluid levels

    If these methods are carefully planned and executed, they allow fighters to make weight without severe dehydration or harmful practices. Crucially, when paired with a planned post-weigh-in refuel and hydration strategy, fighters can restore glycogen, electrolytes, and fluids efficiently. This supports optimal performance in the ring rather than leaving the fighter drained or compromised.

    Lack of Access to Sports Science

    Many gyms, particularly smaller or more traditional ones, do not have access to sports dietitians, exercise physiologists, or evidence-based coaching resources. Fighters in the US, Europe, Asia, and elsewhere often rely on rapid, extreme methods because safer alternatives are not widely known or culturally reinforced.

    In my research, I have come across countless examples of fighters using unsafe methods that look effective in the short term but are detrimental to long-term health.

    Economic and Competitive Pressures

    For many fighters, making weight is not just a sporting challenge, it is a financial necessity. Fight purses, sponsorships, and career opportunities often depend on competing in a certain weight class. Coaches and gyms feel pressure to ensure fighters hit their target weight, which reinforces unsafe practices.

    Peer pressure also plays a role. Fighters often imitate each other, normalizing practices like sauna sweating, excessive cardio, and vomiting, regardless of the discipline or country.

    The Risks of Extreme Weight-Cutting

    Rapid weight loss can lead to:

    • Dehydration and electrolyte imbalance, causing dizziness, cramps, and impaired muscle function
    • Kidney stress, especially with repeated cycles of fluid restriction
    • Cognitive impairment, affecting reaction time, focus, and decision-making
    • Cardiac risk, particularly dangerous for fighters with pre-existing conditions

    Even methods that seem effective in the short term can have lasting health consequences, especially if repeated over a fighter’s career.

    Evidence-Based Alternatives

    Safer strategies focus on gradual, planned changes rather than drastic measures:

    • Structured fat loss, reducing body fat slowly through nutrition and training
    • Hydration and water manipulation, using carbohydrates, fibre, and sodium strategically when combined with gradual body weight reduction
    • Planned refuel and rehydration, restoring glycogen, fluids, and electrolytes after weigh-in to maximize performance
    • Education, teaching coaches and fighters about evidence-based sports science

    In my work with athletes and through research, I have seen how these strategies protect health while allowing fighters to make weight safely and perform at their best.

    Take-Home Message

    Unsafe weight-cutting practices are common across combat sports worldwide. Tradition, short-term performance pressures, limited access to sports science, and economic factors all contribute to their persistence.

    By applying evidence-based nutrition, gradual weight management, strategic water manipulation, and post-weigh-in refuel plans, fighters can perform at their best while minimizing health risks. As someone who works in nutrition and research, I hope more gyms and coaches will prioritise long-term safety alongside competitive success.

    Disclaimer

    This article is for educational purposes only and does not replace personalized medical, nutrition, or sports science advice. Any strategies for weight management or hydration should be discussed with a qualified healthcare professional, dietitian, or coach, particularly for athletes with medical conditions. Individual needs, responses, and safety must always be considered.

  • Vitamin D Production in the Skin: Key Mechanisms, Influencing Factors, and Health Effects by Sarah Curran MSc

    While studying for my skin science lectures today at UCD, I thought it would be a good idea to write a post on vitamin D. We covered vitamin D production in the skin, and it was one of the most interesting topics so far, because it sits at the intersection of dermatology, nutrition, and overall health. I loved it because it bridges skin science with an essential component of nutrition and public health. This is especially relevant in Ireland, where vitamin D deficiency is common due to limited year round UVB availability.

    Vitamin D produced in the skin is the primary source of this nutrient for humans. Unlike most vitamins, vitamin D functions as a hormone precursor and depends heavily on exposure to ultraviolet B (UVB) radiation from sunlight. Its production varies widely between individuals and environments, influenced by skin characteristics, age, geographic location, season, and lifestyle behaviors such as clothing and time spent outdoors.

    How Vitamin D Is Made in the Skin

    Cutaneous vitamin D synthesis begins when UVB radiation (approximately 290 to 315 nm) penetrates the skin and interacts with a cholesterol derived molecule called 7-dehydrocholesterol (7-DHC) in the epidermis.

    Step by step process:

    1. Photochemical conversion
      UVB converts 7-DHC into previtamin D₃.
    2. Thermal isomerization
      Previtamin D₃ gradually transforms into vitamin D₃ (cholecalciferol) over hours to days through heat dependent rearrangement.
    3. Transport in the bloodstream
      Vitamin D₃ enters circulation bound to vitamin D binding protein.
    4. Activation in organs
    • Liver converts it to 25-hydroxyvitamin D (25(OH)D), the main circulating form
    • Kidney converts it further to 1,25-dihydroxyvitamin D (1,25(OH)₂D), the biologically active hormone

    Importantly, skin cells (keratinocytes) themselves possess the enzymes needed to complete this activation locally. This allows vitamin D to act within the skin through autocrine and paracrine signaling, influencing nearby cells directly.

    Major Determinants of Skin Vitamin D Production

    The efficiency of cutaneous vitamin D synthesis depends on both environmental exposure to UVB and individual biological factors.

    UVB Availability

    UVB intensity varies with latitude, season, time of day, and atmospheric conditions such as ozone and clouds. Production is highest at low latitudes, during summer months, and around midday when the sun is high in the sky. At latitudes of approximately 42° North or higher, winter sunlight may provide virtually no effective UVB for vitamin D synthesis, a period often referred to as a vitamin D winter.

    Skin Pigmentation

    Melanin absorbs UVB radiation before it can reach 7-DHC. Darker skin significantly reduces vitamin D production efficiency, and individuals with deeply pigmented skin may require 5 to 10 times longer exposure than those with very light skin to produce the same amount.

    Age

    Skin capacity declines with aging due to reduced 7-DHC content. Approximately 13 percent decrease in vitamin D₃ production occurs per decade, but older adults still retain the ability to synthesize vitamin D with sufficient exposure.

    Body Surface Area Exposed

    The amount of uncovered skin strongly influences output. More exposed skin leads to greater production, while clothing and sunscreen markedly reduce UVB penetration.

    How Much Sun Is Needed?

    Effective synthesis occurs primarily when the sun is high enough in the sky, typically between about 10:00 and 16:00 during months when UVB is sufficient. Short exposures can generate meaningful amounts of vitamin D, but optimal conditions vary by skin type. Modeling studies estimate that exposing about 25 percent of the body surface could produce roughly 1,000 IU in minutes under strong UVB, around 5 minutes for very light skin and up to 25 minutes for very dark skin. Short, near noon exposures of limited skin area can increase circulating vitamin D₃ in both younger and older adults after a single session, though measurable changes in 25(OH)D may require repeated exposure. At mid latitudes, winter months may provide little to no cutaneous production for several consecutive months.

    Balancing Benefits and Risks

    The same UVB radiation that produces vitamin D also causes DNA damage and increases skin cancer risk. Public health guidance therefore emphasizes small, non burning exposures, avoidance of sunburn, and moderation rather than prolonged sunbathing. With excessive sunlight exposure, previtamin D₃ and vitamin D₃ are converted into inactive compounds, which prevents vitamin D toxicity from sun exposure alone.

    Health Benefits of Vitamin D

    Vitamin D plays essential roles throughout the body.

    Bone and Muscle Health

    Vitamin D is crucial for calcium and phosphate absorption and proper bone mineralization. Deficiency can cause rickets in children and osteomalacia in adults. Adequate levels help reduce osteoporosis risk, fractures, and muscle weakness and falls, particularly in older individuals.

    Immune Function

    Vitamin D acts as a broad immune regulator.

    Innate Immunity: Immune cells can activate vitamin D locally and use it to produce antimicrobial peptides such as cathelicidin and defensins, kill bacteria, fungi, and respiratory viruses, enhance pathogen clearance mechanisms, and support barrier integrity in tissues like the lungs and gut. Low vitamin D status is associated with increased susceptibility to respiratory infections.

    Adaptive Immunity: Vitamin D influences T cell and B cell responses by reducing pro inflammatory immune activity, promoting regulatory pathways that limit autoimmunity, and suppressing excessive antibody production. Overall, it supports pathogen defense while reducing harmful inflammation. Deficiency has been associated with higher risk of autoimmune conditions such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and others, although clinical trial evidence varies.

    Chronic Disease Outcomes

    Evidence for broader disease prevention is more limited. Large trials show little effect of routine supplementation in vitamin D sufficient adults on cardiovascular disease, diabetes, or overall cancer incidence. Some analyses suggest modest reductions in cancer mortality and possibly overall mortality, especially in older populations. Vitamin D receptors are present in most tissues, and active vitamin D influences the expression of hundreds of genes related to inflammation, metabolism, cell growth, and oxidative stress.

    How to Increase Vitamin D Levels

    Supplements: Daily vitamin D₃ supplementation consistently raises blood levels. Higher doses may be required if deficient under medical supervision. In deficient individuals, supplementation raises vitamin D levels more effectively than sunlight guidance alone.

    Fortified Foods: Because natural dietary sources are limited, fortification is considered a key population strategy. Common fortified foods include milk, yogurt, cereals, bread, oils, juices, and eggs. These can significantly increase vitamin D status depending on dose and duration.

    Safe Sun Exposure: Sunlight can produce large amounts of vitamin D but is unpredictable due to environmental and personal factors. Typical guideline sun exposure produces only modest increases in vitamin D levels, especially in deficient adults. Sun exposure should be used as a complement, not the main strategy, particularly for those who are deficient.

    Dietary Sources: Natural foods include fatty fish, egg yolks, liver, and UV exposed mushrooms. Diet alone rarely meets recommended intakes. Weight loss can modestly improve vitamin D status by releasing vitamin D from fat stores, but the effect is usually small.

    Take Home Message

    Vitamin D synthesis in the skin is a UVB dependent process that converts 7-dehydrocholesterol into vitamin D₃, which is then activated in the body to function as a hormone. Production efficiency is determined primarily by UVB availability shaped by latitude, season, and time of day, along with individual factors such as skin pigmentation, age, clothing, and sunscreen use.

    Short, regular, non burning sun exposures can generate substantial vitamin D when UVB is sufficient. However, at higher latitudes or during winter months, skin production may be minimal or absent, making dietary intake and supplementation increasingly important. Vitamin D is essential for bone health, plays a significant role in immune regulation, and influences many physiological processes. In countries with limited sunlight such as Ireland, deficiency is common, which makes awareness, nutrition, fortified foods, and supplementation particularly important for maintaining optimal health.

    Disclaimer

    This article is for educational purposes only and is not a substitute for medical advice. Always consult a qualified healthcare professional regarding supplementation or health concerns.

    For more evidence based health, fitness, and skin science content, follow @SarahCurranFitPro on Instagram.