9 Vitamins and Nutrients That Actually Support Hair Growth, Ranked

The shampoo aisle has always had better marketing than results. Thickening serums, scalp tonics, keratin-infused conditioners: they treat the outside of a problem that often starts from within. If your hair is thinning, shedding more than usual, or simply refusing to grow past a certain length, the answer is more likely sitting in a nutrient gap than in a bottle of volumising shampoo.

The UK hair health supplements market hit $155.8 million in 2025 and is projected to reach $259.7 million by 2033, growing at 6.6% annually. That growth is not driven by marketing alone. It reflects a genuine shift in how women understand hair health: not as a cosmetic issue, but as a nutritional one.

The honest caveat: not every vitamin sold for hair growth has the science to back it up. Some nutrients have strong, consistent clinical evidence. Others have moderate support, or only help when you are genuinely deficient. This list ranks all nine honestly, so you know exactly what you are taking and why.

What this list covers: The nine most clinically relevant vitamins and nutrients for hair growth, ranked from strongest to most supporting evidence, with the science explained plainly.

1. Iron: The Most Common Deficiency Driving Hair Loss in Women"

Evidence strength: Strong

Iron sits at the top of this list for one simple reason: it is the world's most common nutritional deficiency, and it is a well-established cause of hair loss. For women in the UK, particularly those with heavy periods, plant-based diets, or postpartum bodies, low iron (specifically low ferritin, the stored form) is frequently the silent driver behind diffuse shedding.

Hair follicle matrix cells are among the fastest-dividing cells in the entire body. They need iron to function. When ferritin levels drop, the body prioritises iron for essential organs, and hair follicles are essentially deprioritised. The result is telogen effluvium: a diffuse, all-over shedding that typically appears two to three months after the deficiency takes hold.

What the research shows

A study of more than 5,000 women found that 59% of those experiencing excessive hair loss had low iron stores, compared to women with moderate or no hair loss. Reversal of iron deficiency in mouse models restored hair growth entirely.

Who needs it most

• Women with heavy menstrual cycles

• Vegetarians and vegans (plant-based iron is less bioavailable)

• Postpartum women

• Anyone who has recently lost significant weight

The practical note: iron works best alongside vitamin C, which significantly improves absorption. Taking iron without vitamin C is a common and easily fixed mistake.

2. Vitamin D: The Deficiency Most UK Women Already Have

Evidence strength: Strong

The UK's lack of sunlight is not just a mood issue. It is a hair issue. Vitamin D deficiency is endemic in the UK population, and there is a well-documented relationship between low vitamin D levels and alopecia areata (an autoimmune condition where the immune system attacks hair follicles) as well as female pattern hair loss.

Vitamin D receptors are found directly in hair follicle cells. The theory is that vitamin D helps stimulate new hair follicle cycling, the process by which follicles move from the resting phase back into active growth. When vitamin D is low, that cycling can stall.

What the research shows

Multiple studies have found significantly lower vitamin D levels in women with alopecia areata compared to healthy controls. A review published in the NIH's PMC database concluded that vitamin D should be supplemented when levels are found to be low, making it one of the few nutrients with a direct clinical recommendation attached.

The practical note: the NHS recommends that everyone in the UK considers a vitamin D supplement during autumn and winter. For hair health specifically, getting your 25(OH)D levels tested is the most useful first step. If you are deficient, supplementing is a clear and evidence-backed action.

3. Zinc: The Follicle Repair Mineral

Evidence strength: Strong (in deficiency); Moderate (in general population)

Zinc is essential for the enzymes that regulate hair follicle function and protein synthesis. Alopecia is one of the most recognisable signs of established zinc deficiency, and hair regrowth following zinc supplementation in deficient patients is well documented.

A study of 312 patients with various forms of hair loss (including telogen effluvium, androgenic alopecia, and alopecia areata) found that all groups had statistically lower zinc concentrations compared to healthy controls. A separate case series showed complete reversal of hair loss in five patients with telogen effluvium after oral zinc supplementation.

The nuance worth knowing

The evidence is strongest when zinc deficiency is confirmed. For women without a documented deficiency, the picture is less clear. That said, zinc deficiency is more common than many people realise, particularly in:

• Vegetarians and vegans (zinc from plant sources is less bioavailable)

• Women with restricted diets or high-stress lifestyles

• Those who consume large amounts of alcohol

The practical note: zinc toxicity is possible with excessive supplementation, so more is not better here. Doses within recommended daily allowances (8-11mg for adult women) are appropriate for general supplementation. Higher therapeutic doses should only be taken under guidance.

4. Biotin (Vitamin B7): The Famous One, With an Important Asterisk

Evidence strength: Strong in deficiency; Weaker than marketed for the general population

Biotin is the most recognisable name in hair supplements, and for good reason: it is the only nutrient with a UK-authorised health claim specifically linking it to the maintenance of normal hair. But that claim is frequently misread as "biotin makes hair grow faster," which the evidence does not fully support.

Here is what the science actually says. Biotin deficiency does cause hair loss, and supplementation in deficient individuals reverses it. Biotin found to be deficient in 38% of women complaining of hair loss in one study, which is significant. The problem is that most people who take biotin supplements are not deficient, and for those without deficiency, the evidence for additional benefit is limited.

Why biotin still belongs in this list

Despite the nuance, biotin earns its place for three reasons:

1. Deficiency is more common than assumed - prolonged antibiotic use, pregnancy, and certain gut conditions all deplete biotin

2. Its role in keratin production - biotin is a cofactor in the metabolic processes that produce keratin, the protein hair is made from

3. The gummy supplement RCT - a 2025 randomised controlled trial published in PMC found that a gummy supplement containing biotin alongside zinc and B vitamins increased hair growth density by 10.1% over 168 days compared to a placebo group that saw a 2% decrease

The practical note: if you are taking high-dose standalone biotin, tell your GP before any blood tests. High doses of biotin can interfere with certain lab results, including thyroid tests and cardiac markers. This is a real and documented issue, not a fringe concern.

5. Vitamin C: The Unsung Enabler

Evidence strength: Moderate (indirect but important)

Vitamin C rarely gets its own headline in hair supplement marketing, but it plays a role that is arguably more practical than most nutrients on this list. Its primary contribution to hair health is not direct: it is what vitamin C does to iron absorption that matters.

Non-haem iron (the type found in plant foods and most supplements) is notoriously poorly absorbed. Vitamin C converts non-haem iron into a form the body can actually use, increasing absorption by up to 67% in some studies. Given that iron deficiency is the leading nutritional cause of hair loss in women, anything that meaningfully improves iron absorption is genuinely significant.

Beyond iron, vitamin C is an antioxidant that helps protect hair follicles from oxidative stress, and it is involved in collagen synthesis, which supports the structure of the hair shaft and scalp.

The practical note: pairing vitamin C with iron in the same supplement (or the same meal) is one of the most evidence-based things you can do for hair health. It is also why multi-nutrient hair formulas tend to outperform single-ingredient supplements.

6. B Vitamins (Folate and B12): The Overlooked Growth Supporters

Evidence strength: Moderate

Folate and vitamin B12 are both involved in the production of red blood cells and DNA synthesis, two processes that directly affect how well hair follicles function. Hair follicle cells divide rapidly and have a high demand for both nucleic acids and amino acids, meaning any shortfall in folate or B12 can translate into slower growth or increased shedding.

The evidence linking B12 and folate to hair loss is not yet definitive enough for blanket supplementation recommendations. But the associations are meaningful. Women presenting with telogen effluvium (diffuse shedding) have been found to have significantly lower B12 and folate levels than healthy controls in several studies. A case-control study of women with premature greying found significantly lower levels of B12, folic acid, and biotin compared to women without premature greying.

Who is most at risk of B12 deficiency

B12 deficiency is particularly relevant for:

• Vegans and vegetarians (B12 is found almost exclusively in animal products)

• Women over 40, as B12 absorption decreases with age

• Those taking metformin (commonly prescribed for PCOS, which also affects hair)

• Anyone with gut absorption issues

The practical note: if you follow a plant-based diet, B12 supplementation is not optional for hair health or general health. The body cannot manufacture B12, and dietary sources are almost entirely animal-derived.

7. Vitamin E (Tocotrienols): The Antioxidant With a Promising Trial

Evidence strength: Emerging

Vitamin E is not the most talked-about nutrient in hair supplements, but it has one of the more intriguing pieces of clinical evidence behind it. A small but well-designed randomised controlled trial found that tocotrienol supplementation (a specific form of vitamin E) produced a 34% increase in hair count over eight months compared to a placebo group that saw a 0.1% decrease.

The mechanism is thought to be antioxidant-related. Oxidative stress in the scalp can damage hair follicles and disrupt the normal growth cycle. Tocotrienols, which are more potent antioxidants than the more common tocopherol form of vitamin E, appear to reduce this oxidative damage at the follicle level.

The honest caveat: this trial was small and has not yet been replicated at scale. It is promising, not conclusive. But for a nutrient that is generally safe at recommended doses and has broad antioxidant benefits beyond hair, it is worth including in a well-rounded hair supplement formula.

The practical note: look for tocotrienols specifically, rather than standard vitamin E (tocopherol). They are different compounds with different mechanisms, and most of the hair-relevant evidence relates to the tocotrienol form.

8. Selenium: A Little Goes a Long Way (In Both Directions)

Evidence strength: Moderate, with a critical caveat

Selenium is an essential trace mineral involved in thyroid hormone metabolism and antioxidant enzyme production. Both of these pathways matter for hair: thyroid imbalances are a well-known cause of hair loss, and antioxidant protection at the follicle level supports healthy growth cycles.

The catch with selenium is that the margin between helpful and harmful is narrow. According to a review of vitamins and minerals in hair loss, too much selenium can actually cause hair loss, making it one of the few nutrients where excess supplementation produces the exact problem you are trying to solve.

The right approach to selenium

The practical note: selenium is best obtained through diet (Brazil nuts, fish, eggs) or as part of a balanced multi-nutrient formula at safe levels. Standalone high-dose selenium supplementation is not recommended without confirmed deficiency.

9. Niacin (Vitamin B3): The Scalp Circulation Booster

Evidence strength: Moderate

Niacin rounds out this list as a supporting player with a clear biological rationale. It improves blood circulation to the scalp, which means hair follicles receive more oxygen and nutrients. Severe niacin deficiency (a condition called pellagra) causes alopecia as one of its symptoms, and hair regrowth follows once levels are restored.

For women without outright deficiency, the evidence for niacin as a standalone hair growth treatment is limited. But its role in scalp microcirculation means it is a useful addition to multi-nutrient formulas, particularly for women who experience hair thinning alongside stress or poor circulation.

Niacin is also one of the B vitamins that can be depleted by certain medications, including isoniazid (used for tuberculosis treatment), making it worth checking if you are on long-term prescription drugs.

The practical note: niacin at higher doses can cause a harmless but uncomfortable "flush" effect (temporary redness and tingling of the skin). Most hair supplement formulas use doses well below the flushing threshold, but it is worth being aware of if you are sensitive.

The Bigger Picture: Why Multi-Nutrient Formulas Outperform Single Ingredients

Reading through this list, a pattern emerges. Very few of these nutrients work in isolation. Iron works better with vitamin C. Biotin works better as part of a B-complex. Zinc and selenium need to be balanced against each other. The clinical trial that produced the strongest results (10.1% increase in hair density) was not testing a single ingredient: it was testing a combination of B vitamins, zinc, and botanical extracts together.

This is why the UK hair health supplements market is increasingly dominated by multi-ingredient formulas. According to Grand View Research, multi-ingredient products held a 67.8% revenue share of the UK market in 2025. The gummy format specifically led all delivery formats with a 34.3% market share, driven by the combination of compliance (people actually take them daily) and bioavailability.

The bottom line: if you are experiencing hair thinning or slow growth, the most evidence-backed approach is a well-formulated multi-nutrient supplement that combines the top-ranked ingredients from this list, rather than chasing a single hero ingredient.

A quick reference: all 9 nutrients at a glance

Hair growth is a slow process. Most clinical studies measure outcomes at 90 to 180 days. Expect to take a consistent daily supplement for at least three months before assessing results, and pair it with adequate dietary protein, which no supplement can replace.

If you are looking for a gummy formula that combines several of the key nutrients from this list, Nurtured Club's Root Renew is formulated specifically for women's hair health, in the gummy format that leads the UK market for compliance and convenience.