GP explains how vitamin and supplement deficiencies can contribute to hair loss – and how too much of certain vitamins might have the same effect.
Hair thinning or balding is something that the majority of adults in the UK (85% of men and 40% of women by age 50) experience. In fact, a study conducted by LloydsPharmacy Online Doctor found that 22% of UK adults reported feeling “very concerned” about potential hair loss and balding, and a further 35% are “somewhat concerned”.
Not only this, but half of all Brits (men and women) surveyed claim they would feel self-conscious if they started losing their hair, a third would feel insecure, and 40% would feel devastated (as opposed to 34% feeling just “saddened”).
Interestingly, three quarters (75%) of men under the age of 35 believe losing their hair would impact their confidence or self-esteem, a number that drops significantly to just 40% for men over 35.
Despite this, women are actually more uneasy with losing their hair and balding, with 59% feeling “concerned” or “very concerned” versus 53% of men. A quarter of men (24%) also said they were “not concerned at all” compared with just 12% of women.
With such heightened emotions experienced when it comes to our hair, and the significant link between vitamins and hair growth, it’s unsurprising that the hair vitamin market is expected to reach £431.6 million by the year 2030.
Interestingly, LloydsPharmacy Online Doctor’s study found that 66% of women are likely to try a supplement or vitamin if they thought it would improve their hair growth, as would over half (55%) of men.
Indeed, certain vitamin deficiencies, such as Iron, Vitamin D, Biotin, Folate, and Vitamin B12 can contribute to hair loss. However, not all vitamins are created equal, and some vitamins can actually cause hair loss if too many are taken – something 64% of women and 65% of men weren’t aware of, despite nearly a fifth of UK adults (17%) currently taking vitamins specifically designed to prevent hair loss.
More than two fifths (44%) admitted to believing that taking more vitamins than the recommended dose would lead to better results.
The most common vitamin to take is Biotin (Vitamin B7), which a quarter (25%) of those surveyed reporting taking, followed by Vitamin D (25%), and Collagen (15%). 7% admitted to taking specific hair gummies with blended vitamins and supplements included.
As for those not partaking, 17% of Brits surveyed don’t think vitamins work, 13% think they are too expensive, and one in 10 (9%) are concerned about side effects.
Sheena Bagga, Pharmacist prescriber at LloydsPharmacy Online Doctor, commented: “There are a number of causes for hair loss, so it’s understandable that a lot of people will turn to supplements and vitamins in search of improvement. Often, this can help the condition – deficiencies in Vitamin D, B12, Iron, Biotin to name a few can all contribute to hair loss, so correcting these through appropriate repletion may improve overall hair health.
“However, it’s important to approach this with caution. Excessive intake of certain vitamins – such as Vitamin A or Selenium – has been linked to hair shedding, and more is not necessarily better with vitamins. Anyone experiencing noticeable hair thinning or loss should seek advice from their GP to identify the underlying cause to determine the most appropriate course of treatment.”
Bagga provided information on different vitamins that can aid hair growth – and those that can lead to thinning.
Vitamin D
Vitamin D is an essential nutrient for many reasons, yet approximately 50% of Brits are deficient. It helps support healthy hair follicles, so a deficiency can lead to increased shedding or thinning.
Bagga says: “A lot of people don’t realise Vitamin D plays a key role in the hair growth cycle, and deficiency has been associated with various types of hair loss – including telogen effluvium (excessive shedding of resting hair) and alopecia areata.
“The NHS recommends that all British adults take Vitamin D supplements throughout the year, and for individuals experiencing hair thinning, checking and correcting this deficiency can be an important part of a broader treatment plan.”
The recommended daily amount of vitamin D is 400 IU for children up to age 12 months, 600 IU for those aged 1 to 70, and 800 IU for those aged 70+.
Biotin
The most common vitamin taken by those in LloydsPharmacy Online Doctor’s survey, Biotin is well known for boosting hair health. Also known as Vitamin B7 or Vitamin H, it’s popular for also aiding in the production of keratin – a protein essential for hair growth.
“For those that are deficient in Biotin, they’re likely to experience brittle hair or increased shedding, so taking a supplement can make a big difference. However, Biotin deficiency is incredibly rare, so unless a doctor has identified low levels, taking extra might not make a big difference,” Bagga explains.
The recommended daily amount of Biotin for children aged 4-6 is 25 micrograms (mcg), children aged 7-10 it’s 30mcg, and for adults and teenagers it is between 30 to 100 mcg.
Iron
One of the most important vitamins for hair growth, iron deficiencies are one of the more common nutrient-related causes of hair loss – especially in women.
Bagga explains: “Iron helps carry oxygen to your hair follicles, so without enough the hair can start to thin or shed more. It’s important not to overdo it though, as too much iron can be harmful, and you won’t notice a difference in your hair if your levels are already normal.”
Low levels of the iron storage protein (ferritin) are common in menstruating women, vegetarians/vegans, and anyone who doesn’t eat red meat.
Currently 8% of Brits take iron supplements specifically to aid hair growth. The recommended daily amount of iron is: 8.7mg for men aged 19 and over; 14.8mg for women aged 19 to 49, and 8.7mg for women aged 50+.
Vitamin A
A crucial vitamin for cell growth – including the cells in your hair follicles – yet Bagga urges caution: “Too much Vitamin A can be a big problem. While a deficiency can lead to hair thinning, overdoing it – especially through supplements – can actually cause hair loss as it disrupts the natural growth cycle of the hair.
“It’s crucial to maintain balanced levels, as both deficiency and excess can impact hair health. Over many years, too much vitamin A can also affect bones, making them more likely to fracture. Monitoring Vitamin A levels through blood tests is recommended for appropriate supplementation.”
The best sources for vitamin A include cheese, eggs, oily fish, milk, yoghurt, and liver products, and the daily recommended amount is 700 micrograms for men and 600 for women, as per the NHS website.
Vitamin B5
Best known for playing a role in the breakdown of fats and carbohydrates for energy, Vitamin B5 can also contribute to hair health by metabolising the fats and proteins that are essential for hair growth.
Sheena Bagga says: “There is limited scientific evidence to explicitly say Vitamin B5 prevents hair loss, and while deficiencies can, in theory, lead to hair thinning, these are extremely rare.
“Excessive amounts of B5 are not guaranteed to boost hair growth, and this should be avoided – too much can cause diarrhoea, nausea, and stomach cramps. Always consult a healthcare professional to determine if a supplement is needed.”
Vitamin B6
Vitamin B6 helps regulate hormone levels, including those related to hair growth, and a deficiency in this vitamin can lead to a deficiency of proteins like keratin, which are crucial for hair structure.
Sheena adds: “A deficiency in B6 isn’t very common, but given the vitamin helps create red blood cells – which carry oxygen and nutrients to the scalp and hair follicles – it is a deficiency that can cause thinning or weak hair.
“However, taking too much B6 over time – especially through high-dose supplements – can lead to nerve issues.”
The recommended daily amount of vitamin B6 is 1.4mg for men and 1.2mg for women, and it’s commonly found in pork, poultry, fish, peanuts, bananas, oats, and milk.
Selenium
Deficiency and excess of Selenium can contribute to hair loss, and as Sheena Bagga says, “the line between ‘just enough’ and ‘too much’ is pretty thin. While low levels can occasionally affect hair growth, it’s high selenium intake that’s more often linked to hair shedding. It’s one of those nutrients where more doesn’t mean better, and it’s important not to exceed the recommended daily dosage.”
Selenium is a powerful antioxidant and micronutrient that is necessary for proper functioning of the body and plays a major role with metabolism and thyroid function.
The recommended daily amount is 75 micrograms for men, and 60 micrograms for women aged 19 to 64 years. Good sources include Brazil nuts, fish, meat, and eggs.
Collagen
Collagen is a trending topic at the moment, with 139k searches on Google Trends in the last month (March 2025), and that’s because it is a protein that is naturally found in hair, so the assumption is that adding more into a diet will increase hair growth and production.
However, research on collagen supplements and hair growth is still emerging, and Bagga warns: “not all collagen products are created equal, so quality and consistency matter more than hype.”
15% of Brits surveyed currently take collagen regularly to aid hair growth.
What to do if you are concerned about hair loss
“It is important to speak with a GP if you’re concerned about hair loss to determine if you’re suitable for treatment, and find the one most effective for you. LloydsPharmacy Online Doctor offers online consultations where you can speak with a qualified clinician and be prescribed the correct treatment.”
