Hair, skin, and nails are among the first places where changes in general health become visible, which is why they prompt so many questions. A run of brittle nails, more hair in the brush than usual, or skin that has turned dry and dull will often send someone looking for a nutritional answer before anything else. Often that instinct is right.
This guide sets out what these tissues are made of, which nutrients contribute to maintaining them, what the everyday factors are that tend to matter more than most people expect, and where the sensible answer is a doctor’s appointment rather than a supplement.
Why Hair, Skin and Nails Are Grouped Together
Keratin is a structural protein produced by the body, and it forms the bulk of hair and nails as well as the outer layer of the skin. The cells that produce it divide rapidly and continuously, which gives these tissues a constant requirement for amino acids, energy, and the vitamins and minerals involved in building proteins.
That high turnover is also why these tissues tend to show changes before anywhere else does. Where nutritional intake may fall short of the body’s needs, or the body is under sustained physical strain, changes in hair, skin, and nails may become apparent relatively early. Visible changes may reflect changes occurring elsewhere in the body.
Although the cells divide rapidly, the tissues they produce take much longer to grow and replace themselves. This is where much of the frustration comes from: hair grows slowly, a fingernail takes several months to replace itself, and toenails are slower still. Skin turns over across several weeks. Any change to diet or lifestyle takes time to become visible, and the hair coming out of the follicle today was formed on the nutritional status of weeks ago. Nothing about these processes works quickly, in either direction.
The Everyday Factors That Matter Most
Before looking at individual nutrients, it is worth considering the everyday factors that most commonly influence hair, skin and nail health.
Diet
Adequate dietary protein supplies the amino acids needed to build many proteins, including the structural proteins found in hair, skin and nails. Overall dietary adequacy also matters, since these tissues rely on a regular supply of energy, protein, vitamins and minerals to support normal growth and renewal. Where energy or nutrient intake falls short of the body’s needs, changes such as increased hair shedding may become more likely. Very low calorie diets and restrictive eating patterns are well-recognised examples of this.
Sleep
Many important repair and recovery processes take place during sleep. Although it is easy to overstate the relationship, persistently poor sleep may influence the body’s ability to maintain the normal processes that support healthy hair, skin and nails. Practical approaches to improving sleep are worth considering if you’re struggling to get a good night’s rest.
Stress
Physical or emotional stress, including illness, surgery, childbirth, and bereavement, can trigger a temporary form of increased hair shedding known as telogen effluvium. It characteristically appears some months after the event rather than during it, which is why the cause is so often missed, and it typically resolves on its own. Stress cannot always be avoided, and there is little value in adding pressure to a difficult period, but recognising the pattern can help put the changes into context.
Ultraviolet (UV) exposure
For skin specifically, ultraviolet exposure is the single biggest external factor driving the visible signs of ageing. The NHS advises taking care not to burn, spending time in the shade between 11am and 3pm from March to October in the UK, and using at least SPF30 sunscreen with a UVA (ultraviolet A) rating of four stars or higher. Protecting the skin from excessive UV exposure is one of the most effective ways to help reduce visible skin ageing over the long term.
Damage
Then there is straightforward mechanical damage, which accounts for a good deal of what is attributed to nutrition. Heat styling, tight ponytails and braids, harsh detergents, frequent gel manicures, and acetone-based removers all damage these tissues physically. Nutrition has no bearing on damage that has already been done to a hair shaft or a nail plate, although easing off the heat and the acetone usually shows within a few months as new growth comes through.
Several common concerns are often mistaken for nutritional problems when other explanations are more likely:
- Hair breaking along its length rather than shedding from the root, which is usually heat or mechanical damage
- White marks on the nails, which are usually the result of minor knocks to the nail matrix rather than a zinc deficiency, despite how persistent that particular idea is
- Dry, flaking skin in winter, which is often related to environmental conditions and changes in the skin barrier
- Increased shedding in the months after illness, surgery, childbirth, or a stressful period, which is usually telogen effluvium and typically temporary
Signs That Should Be Investigated by a Doctor
Most changes to hair, skin and nails turn out to be ordinary, but some warrant medical assessment. Alongside the everyday factors discussed above, certain changes may indicate an underlying condition that requires diagnosis. In these situations, identifying the underlying cause should come before considering nutritional support or supplements.
Sudden hair loss, hair loss in distinct patches, or hair loss accompanied by scalp pain, itching, redness, or scaling all warrant medical assessment. So do marked nail changes: pitting of the nail surface, separation of the nail from the nail bed, marked changes in colour, or a dark line appearing under a nail. Persistent skin changes, new or changing moles, and rashes that do not settle should also be seen.
These signs can have a range of underlying causes, including thyroid disorders, iron deficiency anaemia, autoimmune conditions such as alopecia areata, psoriasis and fungal nail infections. The important first step is to identify the underlying cause so that appropriate treatment can begin. This may involve blood tests, a physical examination or referral to a specialist.
If you are taking supplements, mention these at your appointment. Some can interact with prescribed medicines, while others may influence the results of certain blood tests.
Nutrients That Have Authorised Roles in Hair, Skin and Nail Health
In the UK, health claims about nutrients can only be made using wording that has been reviewed and approved by regulators, and that wording is held on a public list called the GB Nutrition and Health Claims Register. The claims below are taken from it. Each describes what a nutrient contributes to maintaining under normal circumstances, and each applies where someone’s intake is adequate rather than offering extra benefit at higher intakes.
Where the medical causes above have been ruled out, the nutrients below are the ones with authorised roles in hair, skin, and nail health. None of them is a means of correcting a problem, and no supplement substitutes for the dietary and lifestyle foundations set out above. In every instance, food and diet are the priority.
Biotin
Biotin contributes to the maintenance of normal hair and normal skin, and it also contributes to normal macronutrient metabolism. Biotin is widely associated with hair, although a biotin deficiency is uncommon in people eating a varied diet, and where intake is already adequate, the evidence that additional biotin does anything further is limited. The NHS position is that most people should be able to get all the biotin they need from their diet. Sources include eggs, liver, nuts, seeds, oily fish, and some vegetables.
High-dose biotin supplementation can interfere with certain laboratory blood tests, including some thyroid and cardiac tests. Anyone due for blood work should mention any biotin supplement to their doctor.
Zinc
Zinc contributes to the maintenance of normal hair, normal nails, and normal skin, and also to normal DNA synthesis and normal protein synthesis, which is what makes it relevant to the cells responsible for producing and renewing these tissues. Zinc from animal sources tends to be more readily absorbed than zinc from plant sources, as phytates in wholegrains and legumes reduce absorption. This is particularly relevant for people following a plant-based diet, who may need to pay closer attention to their zinc intake. Shellfish, meat, seeds, legumes, and wholegrains are the main dietary sources.
Selenium
Selenium contributes to the maintenance of normal hair and normal nails. Brazil nuts are a notably concentrated source, although the selenium content varies depending on where they were grown. Selenium has a relatively narrow margin between an adequate intake and an excessive one, and excessive intake over a long period is associated with a condition called selenosis, the signs of which include brittle nails and hair loss. Fish, meat, eggs, and Brazil nuts are all good sources, and there is rarely a case for high-dose selenium supplementation without a specific reason.
Vitamin C
Vitamin C contributes to normal collagen formation for the normal function of skin, as well as contributing to normal collagen formation for the normal function of bones, cartilage, gums, teeth, and blood vessels. This is the substantiated part of the collagen conversation. The body synthesises its own collagen, and vitamin C is required as a cofactor in that process. Peppers, citrus fruits, berries, brassicas such as broccoli and Brussels sprouts, and potatoes all contribute meaningfully to your dietary intake.
Vitamin A
Vitamin A contributes to the maintenance of normal skin. Liver, dairy, and eggs provide preformed vitamin A, while beta-carotene from orange and dark green vegetables is converted by the body as needed.
There is an important safety caveat. Vitamin A can accumulate in the body, and high intakes can be harmful. The NHS advises that anyone who is pregnant or trying to conceive should avoid liver and liver products, and should avoid supplements containing vitamin A unless advised otherwise by a doctor or midwife. This also includes cod liver oil, which is naturally rich in preformed vitamin A.
Riboflavin and Niacin
Both riboflavin and niacin contribute to the maintenance of normal skin, and both are involved in energy metabolism. The eight B vitamins work together across many metabolic pathways and are often provided together in a balanced B-complex rather than taken in isolation. Dairy, eggs, meat, fish, wholegrains, and fortified cereals all contribute to your intake.
Copper
Copper contributes to normal hair and skin pigmentation, and to the maintenance of normal connective tissues. Shellfish, nuts, seeds, wholegrains, and cocoa are dietary sources. Copper deficiency is uncommon in the UK.
Iodine
Iodine contributes to the maintenance of normal skin. Intake across the UK is variable, particularly among people who do not eat dairy or fish, as these are the main sources alongside eggs. Seaweed can contain very high and inconsistent levels of iodine, and the NHS advises against eating it more than once a week, particularly during pregnancy.
Iron
Iron is a different case. Its authorised roles are in the normal formation of red blood cells and haemoglobin and in the reduction of tiredness and fatigue.
There is no authorised claim linking iron to hair. The relationship between iron status and hair shedding is discussed in clinical literature, but as covered above, that belongs with a doctor rather than with a supplement. Iron status is assessed by a blood test, and iron should not be supplemented without a confirmed need, because excess iron accumulates and can be harmful. Anyone who suspects low iron should ask their doctor for a blood test to confirm rather than starting a supplement on the strength of a symptom. Red meat, pulses, fortified cereals and dark green vegetables are the main dietary sources. Consuming vitamin C alongside plant sources of iron can help the body absorb that iron more effectively.
What About Collagen, Silica, Keratin and the Rest?
A number of ingredients appear widely in hair, skin, and nail products without carrying authorised claims on the GB Register. That is a specific and limited statement: it means the claim has either not been submitted for authorisation or has not been substantiated to the standard required. It says nothing about whether an ingredient is useful, and research on several of them is ongoing.
Collagen is the most prominent example. The body synthesises its own collagen from amino acids, and collagen taken by mouth is digested into peptides and amino acids in the same way as other dietary proteins. Research into whether specific collagen peptides have effects beyond their amino acid content continues, but no authorised claim currently exists. The substantiated position is the one covered above: vitamin C contributes to normal collagen formation for the normal function of skin.
Silica, keratin, and methylsulfonylmethane (MSM) are also widespread in this category and similarly without authorised claims.
Omega-3 and vitamin E are different again. Both have authorised claims, but not for skin. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contribute to normal heart function and to the maintenance of normal brain function and vision, and vitamin E contributes to the protection of cells from oxidative stress. Neither carries an authorised health claim relating to skin appearance, although both are often included in products marketed for skin health.
Choosing and Using a Supplement Sensibly
Food supplements are intended to supplement a varied and balanced diet rather than replace it. Where dietary intake is inadequate, addressing this is likely to have a greater impact than relying on any single vitamin or supplement.
Where a supplement is appropriate, a few practical points apply. The form of a nutrient can influence how it is absorbed and used by the body, although this varies between nutrients, and some supplements use forms selected for quality or bioavailability. When choosing a multivitamin and mineral or individual nutrients from our Hair, Skin & Nails range, check the labels carefully if combining products. Some nutrients, including vitamin A, selenium and zinc, have established safe upper intake levels and may be present in more than one supplement.
The NHS advises everyone in the UK to consider taking a daily vitamin D supplement of 10 micrograms during autumn and winter, when vitamin D levels often fall. Anyone trying to conceive or in the first 12 weeks of pregnancy is advised to take 400 micrograms of folic acid daily, and vitamin D is advised throughout pregnancy.
Anyone taking prescribed medication, who is pregnant or breastfeeding, or who has an existing health condition should speak to a doctor or pharmacist before starting a new supplement.
Hair, Skin and Nail Health Over Time
Hair, skin, and nails reflect general health, which is why the useful questions are usually broader than which vitamin to buy. Changes take months to appear in either direction, given how slowly these tissues renew. Mechanical and environmental factors, from heat styling to sun exposure to acetone, explain more than nutrition does. Specific nutrients do have defined roles in maintaining these tissues normally, and getting enough of them from food is the sensible baseline. But as always, sudden or persistent changes need a doctor’s input.
These tissues also change with age: hair density reduces, nails grow more slowly and can become more brittle, and skin loses firmness and moisture. These changes are a normal part of ageing, and no diet or supplement can prevent them. Good nutrition supports general health and wellbeing throughout, which is worth doing on its own terms rather than as a way of holding age-related change at bay.
Our nutrition team is always happy to talk through general nutritional support if it would help.
Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle.
Frequently Asked Questions
Do hair, skin and nails vitamins really work?
It depends on where someone is starting from. Where intake of a specific nutrient is inadequate, correcting that may make a difference to normal maintenance of these tissues. Where intake is already adequate, the evidence for additional benefit from higher intakes is limited. Nutrients including biotin, zinc, and selenium have authorised roles in maintaining normal hair, and zinc and selenium in maintaining normal nails, but those roles relate to normal maintenance rather than improvement.
Does the NHS recommend biotin supplements?
The NHS position is that most people should be able to get all the biotin they need from a varied and balanced diet, and biotin deficiency is uncommon in the UK. Biotin does contribute to the maintenance of normal hair and normal skin, but there is no general NHS recommendation to supplement it. Anyone due to have blood tests should mention any biotin supplement to their doctor, as it can interfere with some test results.
What causes brittle or splitting nails?
Brittle nails are common and the cause is more often environmental than nutritional. Repeated wetting and drying, detergents and cleaning products, gel manicures and acetone-based removers, and cold weather all weaken the nail plate. Nails also tend to become more brittle with age. Where brittleness appears suddenly, affects all the nails, or comes with other changes such as pitting or separation from the nail bed, see a doctor, as some underlying conditions affect the nails.
Are white spots on nails a sign of zinc deficiency?
This is one of the most persistent ideas about nails, and usually it is not the explanation. White marks on the nails, known as leukonychia, are most commonly the result of minor knocks or pressure on the nail matrix, which is the area under the base of the nail where the nail plate is formed. Because nails grow slowly, the mark appears weeks after the knock that caused it, which is why the connection is rarely made. The link to zinc deficiency is widely repeated but not well supported.
How long does it take for dietary changes to show in hair or nails?
Longer than most people expect. Hair and nails grow slowly, and any change to diet or supplementation shows first at the root, so it takes months before it becomes visible along the length. A few weeks is generally too short a period to judge the effect of a dietary change.
Can supplements help with hair thinning?
Hair thinning has many possible causes, and nutrition is just one of them. Androgenetic hair loss, thyroid conditions, iron deficiency anaemia, autoimmune conditions, medication side effects, and telogen effluvium following illness or stress can all present as thinning or increased shedding. Because the causes differ so much and the treatment depends entirely on which one is involved, thinning that is sudden, patchy, or persistent should be assessed by a doctor rather than approached with a supplement first. Where thinning coincides with perimenopause or menopause, there is more on why hair changes at that stage and what else can contribute.
