Hair, Skin and Nails Supplements: What Do They Actually Do?

Hair, skin and nail supplements make an appealing promise.

Take the right combination of vitamins and minerals and, over time, healthier hair, clearer skin and stronger nails should follow.

Nutrition certainly matters to all three.

But hair loss, brittle nails and changes to the skin can have many causes, and a supplement cannot correct every one of them.

The useful place to start is understanding what nutrients can do, what happens when you are deficient, and why adding more is not always the answer.

The short version

Hair, skin and nails all depend on adequate nutrition.

Deficiencies in certain nutrients can contribute to changes in their appearance or structure, which is one reason supplements containing vitamins and minerals are marketed for beauty.

But correcting a deficiency is not the same as showing that large additional doses improve already healthy hair, skin or nails.

Biotin is a good example. Biotin deficiency can cause hair loss, skin changes and brittle nails, but deficiency is rare. Research supporting high-dose biotin for hair growth in otherwise healthy people is limited.

High-dose biotin can also interfere with some laboratory tests, particularly certain thyroid tests, so your doctor or laboratory should know if you take a supplement containing a substantial amount of biotin.

Persistent hair loss or unexplained nail changes should not automatically be treated with a beauty supplement. Iron deficiency, thyroid problems, illness, stress and other conditions can sometimes be involved.

Why does nutrition affect hair, skin and nails?

Hair, skin and nails are living tissues, or are produced by living tissues, and depend on a steady supply of energy, protein, vitamins and minerals.

That means poor nutrition can show up physically.

For example, severe or prolonged nutrient deficiencies may affect hair growth, skin health or nail structure.

But that does not mean every change you notice is caused by a vitamin deficiency.

The NHS notes that temporary hair loss can occur after illness, stress, weight loss or iron deficiency. Nail changes can have causes ranging from repeated exposure to water and cleaning products to fungal infection, psoriasis, iron deficiency and thyroid disease.

So the first question should not always be:

"Which supplement do I need?"

Sometimes the better question is:

"Why has this changed?"

What is biotin?

Biotin is a water-soluble B vitamin, sometimes called vitamin B7.

The body needs it for enzymes involved in the metabolism of fats, carbohydrates and amino acids.

Biotin deficiency can cause symptoms including thinning hair, skin rashes and brittle nails.

That biological connection is one reason biotin became such a popular ingredient in hair, skin and nail products.

But there is an important detail.

Biotin deficiency is rare.

The US National Institutes of Health notes that severe deficiency has not been reported in healthy people eating an ordinary mixed diet, and typical Western diets generally provide adequate amounts.

Does more biotin make hair grow faster?

There is not good evidence that it does in people who are already getting enough biotin.

A 2024 review looking specifically at oral biotin for hair found only three eligible studies. The best-quality placebo-controlled study found no difference in hair growth between biotin and placebo, while the remaining studies involved particular patient groups and had important limitations.

An earlier review reached a similar conclusion. Reports of benefit largely involved people with an underlying condition or deficiency rather than healthy people simply taking extra biotin.

That does not mean biotin is useless.

It means there is a difference between:

needing biotin

and

assuming that a very large dose will improve healthy hair.

Those are not the same thing.

What about brittle nails?

Biotin is also commonly promoted for stronger nails.

There are some small older studies suggesting that high-dose biotin may improve brittle nails in certain people.

The problem is that these studies were very small, often lacked placebo groups and did not always establish whether participants were deficient in biotin beforehand.

The NIH therefore describes the evidence for hair, skin and nail benefits as limited.

Brittle nails can also have many causes unrelated to biotin.

Age, frequent wetting and drying of the hands, cleaning products, fungal infections and medical conditions can all affect nails.

If a nail changes colour, shape or structure without an obvious reason, it can be worth investigating rather than assuming a supplement will fix it.

What about skin?

Skin depends on adequate nutrition too.

A balanced diet provides protein, essential fats, vitamins and minerals needed throughout the body, including the skin.

But the phrase "skin health" is extremely broad.

Dryness, acne, pigmentation, eczema, ageing and other skin concerns have different causes. A multinutrient supplement cannot reasonably be expected to address all of them.

For most people, getting the basics right matters more: a varied diet, appropriate skincare, sun protection and investigating persistent skin problems where necessary.

The NHS advises that most people should be able to obtain the vitamins and minerals they need through a varied and balanced diet.

Which nutrients are relevant?

Hair, skin and nail products often contain a long list of nutrients.

Some genuinely have recognised roles in normal physiology.

For example, certain B vitamins are involved in energy metabolism, vitamin A has roles in maintaining normal skin, and minerals such as zinc contribute to many normal processes in the body.

That does not mean putting all of them into one product guarantees more hair growth or better skin.

Nutrients usually matter most when intake is inadequate.

A useful way to think about a multinutrient supplement is as additional nutritional intake, rather than as a cosmetic treatment.

Hair loss deserves a little more caution

Hair loss is particularly easy to oversimplify.

Normal hair shedding happens every day, and some forms of hair loss are genetic.

Temporary hair loss can also follow illness, stress, significant weight loss or iron deficiency. Thyroid problems can cause hair changes too.

That means somebody experiencing noticeable or persistent hair loss may benefit more from finding the cause than from cycling through different supplements.

The NHS advises seeing a GP if you are worried about hair loss, particularly before spending money on commercial treatments.

A supplement may still be appropriate in some situations, but it should not hide a problem that needs investigating.

One important thing to know about high-dose biotin

Biotin is water-soluble and is generally well tolerated.

But high doses have a less obvious risk.

They can interfere with certain laboratory tests.

Some laboratory methods use biotin as part of the testing process. Large amounts of biotin circulating in the blood can interfere with these assays and cause results to appear falsely high or falsely low.

In May 2025, the MHRA specifically reminded healthcare professionals that biotin can interfere with thyroid-function laboratory tests, with the risk increasing at higher doses.

The NIH notes that other laboratory tests can also potentially be affected.

This matters because an incorrect result could lead to a wrong diagnosis or inappropriate treatment.

So if you take a high-biotin hair, skin and nail supplement and are having blood tests, tell your doctor and the person taking or analysing the sample that you take biotin.

Do not simply stop prescribed medicines or alter medical treatment yourself.

What about vitamin A?

Vitamin A plays important roles in normal vision, immune function and maintaining healthy skin.

But unlike the idea that "more vitamins must be better", too much preformed vitamin A can be harmful.

This is particularly important during pregnancy.

The NHS advises pregnant women to avoid supplements containing vitamin A in the form of retinol because excessive vitamin A can harm a baby's development.

That is why the form of vitamin A on a supplement label matters.

Anyone who is pregnant, trying to become pregnant or unsure whether a supplement is appropriate should check the label and seek appropriate advice.

Do you need a hair, skin and nail supplement?

Not necessarily.

If you eat a varied diet and have no reason to suspect a deficiency, a supplement may not produce a visible difference.

That does not mean nobody will find one useful.

Someone with a restricted diet, low intake of particular nutrients or another identified nutritional need may have a different reason for taking a multinutrient supplement.

The useful distinction is between:

supplementing your diet

and

treating unexplained hair, skin or nail changes.

The first can sometimes be reasonable.

The second may need more investigation.

A note about Khan Nutrition Hair, Skin & Nails Complex

Our Hair, Skin & Nails Complex is a multinutrient gummy designed for adults.

The directions are two gummies daily.

The formula contains several vitamins and minerals, including 5,000 µg of biotin per daily serving.

It is suitable for vegetarians and vegans, and it is halal.

Because that is a high amount of biotin, we think the laboratory-test issue is important enough to state clearly: if you are having blood tests, tell your doctor or laboratory that you take a high-biotin supplement, particularly if thyroid tests are involved.

The formula also contains vitamin A in the form of retinyl acetate. Because supplements containing preformed vitamin A should be avoided during pregnancy, this product is not recommended during pregnancy.

We do not describe the product as a treatment for hair loss, skin conditions or nail disease.

If you are experiencing unexplained or significant changes in any of those areas, finding out why is more useful than simply increasing the dose.

Explore Hair, Skin & Nails Complex Gummies

What is worth remembering?

Nutrition matters to hair, skin and nails.

But that simple fact is often stretched into the idea that taking very high amounts of individual nutrients must make them grow faster, stronger or healthier.

The evidence does not support such a simple relationship.

Biotin is useful when the body needs biotin. That does not mean 5,000 µg is a proven hair-growth treatment for someone who already has adequate biotin status.

Hair loss and nail changes can also have causes that a beauty supplement will never address.

So if you choose a hair, skin and nail supplement, treat it as exactly that: a supplement to your diet.

And if your body is showing you a persistent or unexplained change, pay attention to the change rather than simply covering it with another supplement.

Sources and further reading

NIH Office of Dietary Supplements: Biotin
An evidence-based overview of biotin, deficiency, hair and nail research and interference with laboratory tests.
Read the NIH biotin fact sheet

MHRA Safety Roundup: Biotin and thyroid tests
UK guidance highlighting the potential for biotin to cause misleading thyroid laboratory results.
Read the MHRA safety update

Biotin for Hair Loss: Teasing Out the Evidence
A 2024 review examining clinical studies of oral biotin for hair growth and quality.
View the research on PubMed

NHS: Hair loss
Guidance on common causes of hair loss and when to seek medical advice.
Read NHS guidance on hair loss

NHS: Pregnancy vitamins and supplements
Guidance on supplements containing vitamin A during pregnancy.
Read NHS pregnancy guidance

Last reviewed: September 2026