The Healthspan Map · Body system

Skin, Hair & Nails

Conditions in this system

Named for a condition in this system

Evidence naming a condition in Skin, Hair & Nails — 42 sources.In the order the Map holds them: strongest evidence first. That is a statement about the evidence, not about what matters most.
Nutrient or leverDirectionStrengthEvidence typeWhat was foundSource
ProteinEat enough ofStrongEstablished clinicalProtein supplies the amino acids for keratin and collagen; deficiency causes hair thinning/shedding, poor skin and impaired wound healing.Protein for keratin/collagen (opens in a new tab)
Sleep quality (refreshed)Watch thisStrongEstablished clinicalPoor sleepers had double the intrinsic skin-ageing score and 30% less skin-barrier recovery at 72 h (higher TEWL).Sleep quality & skin ageing (opens in a new tab)
Vitamin CEat enough ofStrongEstablished clinicalVitamin C is essential for collagen hydroxylation; deficiency (scurvy) causes fragile skin, corkscrew hairs, poor wound healing and bleeding.Vitamin C & collagen (scurvy) (opens in a new tab)
ZincEat enough ofStrongEstablished clinicalZinc deficiency causes dermatitis (acrodermatitis enteropathica), alopecia and impaired wound healing.Zinc & skin/wound healing (opens in a new tab)
Added SugarsDon't overdoModerateReview / narrativeExcess added sugar drives AGE formation that cross-links and stiffens collagen, accelerating skin ageing."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
Anchor foodsWatch thisModerateReview / narrativeA nutrient-dense whole-food diet supplies the protein, antioxidants and fats needed for skin repair and delayed ageing.Whole-food diet & skin repair (opens in a new tab)
Biotin (B7)Eat enough ofModerateReview / narrativeBiotin deficiency causes brittle nails, alopecia and scaly dermatitis (but supplements only help if truly deficient).Biotin & hair/nails (opens in a new tab)
Cardio (moderate + intervals)Do thisModerateRCT / trialA 16-week RCT found aerobic training significantly improved skin elasticity and upper dermal structure.Aerobic training & skin (opens in a new tab)
Colours a dayWatch thisModerateReview / narrativeCarotenoids, flavonoids and polyphenols from colourful plants protect skin from UV/ROS oxidative damage.Antioxidants & photoprotection (opens in a new tab)
Cook real foodDo thisModerateReview / narrativeWater-based cooking (vs high-heat browning) lowers preformed dietary AGEs that damage skin collagen."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
CopperEat enough ofModerateReview / narrativeCopper (lysyl oxidase) cross-links collagen/elastin; deficiency causes depigmentation, spiral hair and impaired wound healing.Copper & collagen cross-linking (opens in a new tab)
Daily movement baselineDo thisModerateReview / narrativeRegular activity roughly doubles cutaneous blood flow and improves vasodilatory function, supporting hydration and healing.Activity & cutaneous blood flow (opens in a new tab)
EPA/DHA (omega-3)Eat enough ofModerateReview / narrativeOmega-3 fatty acids support the skin lipid barrier and hydration and reduce inflammatory skin conditions and photoageing."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
IronEat enough ofModerateReview / narrativeIron deficiency (low ferritin) is the most common nutritional cause of hair loss, plus brittle nails and dry skin.Iron/ferritin & hair loss (opens in a new tab)
Niacin (B3)Eat enough ofModerateReview / narrativeNiacin deficiency causes pellagra: photosensitive dermatitis (plus diarrhoea and dementia).Niacin & pellagra (opens in a new tab)
Oral & skin careDo thisModerateReview / narrativeDaily skincare, sun protection (UV drives ~80% of facial ageing) and gentle cleansing preserve the barrier and collagen.Skincare & sun protection (opens in a new tab)
Oral & skin careDo thisModerateRCT / trialDaily skincare, sun protection (UV drives ~80% of facial ageing) and gentle cleansing preserve the barrier and collagen.Sunscreen and prevention of skin aging: a randomized trial, Ann Intern Med 2013 (opens in a new tab)
SeleniumEat enough ofModerateReview / narrativeSelenium supports keratin and antioxidant defence; deficiency contributes to hair and nail changes.Selenium & hair/nails (opens in a new tab)
SeleniumDon't overdoModerateReview / narrativeSelenium toxicity (selenosis) causes hair loss and brittle, discoloured nails plus skin lesions.Selenosis & hair/nails (opens in a new tab)
Sleep durationWatch thisModerateReview / narrativeCollagen synthesis, cellular repair and wound healing peak during sleep; short sleep impairs all three.Sleep & skin repair (opens in a new tab)
Strength (resistance)Do thisModerateRCT / trialIn the same RCT, resistance training uniquely increased dermal thickness and raised dermal ECM/collagen gene expression.Resistance training & dermis (opens in a new tab)
Sugary drinks & snacks — cut backDo thisModerateReview / narrativeExcess sugar cross-links collagen/elastin into AGEs, stiffening skin and accelerating wrinkling."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
Tobacco / vaping — quitDo thisModerateReview / narrativeCigarette smoke degrades collagen/elastin, depletes vitamin C, impairs wound healing and causes premature ageing and hair loss.Smoking & skin (opens in a new tab)
Ultra-processed food — cut backDo thisModerateReview / narrativeUltra-processed foods high in refined sugar and trans fats promote inflammation, acne and AGE formation."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
Vitamin A (RAE)Eat enough ofModerateReview / narrativeVitamin A deficiency causes follicular hyperkeratosis (phrynoderma), dry skin and impaired epithelial repair.Vitamin A & epithelium (opens in a new tab)
Vitamin A (RAE)Don't overdoModerateEstablished clinicalVitamin A toxicity causes dry, cracked skin, cheilitis, hair loss and brittle nails.Hypervitaminosis A & skin (opens in a new tab)
Vitamin DEat enough ofModerateReview / narrativeVitamin D regulates the hair-follicle cycle and is associated with alopecia areata and telogen effluvium when deficient.Vitamin D & hair follicle (opens in a new tab)
Vitamin EEat enough ofModerateReview / narrativeVitamin E is a lipid-soluble antioxidant that protects skin lipids and supports elasticity and photoprotection.Vitamin E & photoprotection (opens in a new tab)
Water / hydrationDo thisModerateEstablished clinicalAdding ~2 L/day water improved superficial and deep skin hydration and biomechanics, especially in low-consumers.Dietary water & skin hydration (opens in a new tab)
Alcohol — cut backDo thisEmergingReview / narrativeExcess alcohol dehydrates skin, promotes ageing and impairs wound healing.Alcohol & skin (opens in a new tab)
Alcohol — cut backDo thisEmergingCohort / observationalExcess alcohol dehydrates skin, promotes ageing and impairs wound healing.Impact of Smoking and Alcohol Use on Facial Aging in Women: Results of a Large Multinational Study, J Clin Aesthet Dermatol 2019 (opens in a new tab)
Breath/mind (slow breathing)Do thisEmergingReview / narrativePhysiological/psychological stress triggers telogen effluvium (delayed shedding); stress reduction supports hair and skin.Stress & telogen effluvium (opens in a new tab)
Cardio / VO2maxWatch thisEmergingReview / narrativeHabitually active people show younger skin composition than sedentary peers.Fitness & skin composition (opens in a new tab)
Carotenoids (provitamin A)Eat enough ofEmergingReview / narrativeDietary carotenoids act as antioxidants that help protect skin against UV-induced oxidative damage.Carotenoids & photoprotection (opens in a new tab)
Folate (B9)Eat enough ofEmergingReview / narrativeFolate deficiency causes cheilitis, hair depigmentation and mucocutaneous hyperpigmentation.Folate & skin (opens in a new tab)
Riboflavin (B2)Eat enough ofEmergingReview / narrativeRiboflavin deficiency causes angular cheilitis, seborrheic dermatitis and glossitis.Riboflavin & skin (opens in a new tab)
Sleep regularityWatch thisEmergingReview / narrativeThe skin has its own circadian system; disruption impairs barrier function and repair.Skin circadian clock (opens in a new tab)
Supplement disciplineDo thisEmergingReview / narrativeSupplements help hair/skin mainly when correcting a proven deficiency; megadosing (A, selenium, zinc) can worsen hair loss.Correcting deficiency vs megadosing (opens in a new tab)
Total SugarsDon't overdoEmergingReview / narrativeHigh overall sugar intake promotes glycation and AGE accumulation in skin."Diet and Skin Aging - From the Perspective of Food Nutrition", Nutrients 2020 (opens in a new tab)
Vitamin B12Eat enough ofEmergingReview / narrativeVitamin B12 deficiency causes hyperpigmentation, nail changes and hair changes.B12 & skin/nails (opens in a new tab)
Vitamin B6Eat enough ofEmergingReview / narrativeVitamin B6 deficiency causes seborrheic dermatitis and cheilitis.B6 & skin (opens in a new tab)
ZincDon't overdoEmergingEstablished clinicalZinc above ~40 mg/day can disrupt hair follicles and induce copper deficiency (itself a cause of hair/skin changes).NIH Office of Dietary Supplements — Zinc (opens in a new tab)

Held for the whole system

Evidence held for Skin, Hair & Nails as a whole — 2 sources.In the order the Map holds them: strongest evidence first. That is a statement about the evidence, not about what matters most.
Nutrient or leverDirectionStrengthEvidence typeWhat was foundSource
Carotenoids (provitamin A)Don't overdoEmergingEstablished clinicalVery high carotenoid intake causes carotenodermia, a harmless yellow-orange skin discoloration; no Upper Limit is set for carotenoids.NIH ODS – Vitamin A & Carotenoids (opens in a new tab)
Tobacco / vaping — quitDo thisEmergingEstablished clinicalSmoking accelerates skin aging and premature wrinkling through vascular and collagen damage.US Surgeon General report (opens in a new tab)