Which vitamin deficiency might lead to hair loss

Hair thinning and shedding can be unsettling, and it is natural to wonder whether a lack of vitamins is part of the picture. In the UK, the most frequent nutritional contributors to diffuse shedding are deficiencies that affect hair-follicle cycling or blood supply to the scalp. Not every case of hair loss is nutritional, and many people will see no change from supplements alone. However, identifying and addressing genuine deficiencies can be an important piece of a broader hair health plan.

This article is for informational purposes only and should not be considered medical advice. Please consult a qualified healthcare professional for personalized guidance and treatment.

Can vitamin deficiency cause hair loss?

Some vitamin deficiencies can be associated with increased hair shedding, often through effects on cell turnover, scalp skin health, or oxygen delivery to follicles. A common pattern is telogen effluvium, where more hairs than usual shift into the shedding phase after a trigger. Triggers can include illness, childbirth, major stress, certain medicines, thyroid issues, and nutritional shortfalls. Correcting an underlying deficiency may help normalise shedding over several months, although results vary and depend on the true cause.

In practice, clinicians often look for broader causes alongside nutrition. For example, thyroid dysfunction, iron deficiency anaemia, and inflammatory scalp conditions may mimic or compound vitamin-related issues. Because different hair loss types have different drivers, a tailored assessment, including blood tests arranged by a GP or local services in your area, is usually the most reliable way to determine next steps.

Vitamins that may be linked to hair loss

Vitamin D: Lower vitamin D levels have been observed in people with some hair loss conditions, including diffuse shedding and certain autoimmune forms. This does not prove causation, but insufficiency is common in the UK, especially in autumn and winter. Improving low levels as advised by a healthcare professional may support overall health and, in some cases, hair-follicle cycling.

Vitamin B12 and folate: Deficiency can reduce red blood cell formation and oxygen delivery, which may contribute to thinning or increased shedding. People with pernicious anaemia, vegan or vegetarian diets without fortified foods, or gastrointestinal conditions may be at higher risk. Normalising levels can take weeks to months and should be guided by blood tests.

Biotin (vitamin B7): True deficiency is rare but can occur with specific genetic conditions, long-term use of certain medicines, or severe malabsorption. While biotin is often marketed for hair, robust evidence for supplementation in people without deficiency is limited. High-dose biotin can also interfere with some laboratory tests; clinicians may advise pausing it before blood testing.

Riboflavin (vitamin B2): Insufficient intake is uncommon but has been linked to hair loss in deficiency states, often alongside skin and mouth changes. Riboflavin is found in milk, eggs, and fortified cereals, so most balanced diets supply adequate amounts.

Vitamin A: Both too little and too much vitamin A can affect hair, but in the UK, excess from supplements is a more typical concern than deficiency. Over-supplementation may lead to increased shedding. Any vitamin A intake should respect recommended limits, especially during pregnancy.

Vitamins possibly associated with thinning hair

When thinning develops, clinicians usually start with history, examination, and targeted blood tests. In the UK, common investigations for diffuse shedding can include full blood count, ferritin, vitamin D, B12 and folate, and thyroid function. Not everyone needs every test; decisions depend on symptoms, diet, medicines, and risk factors.

Who might consider testing? People with restrictive diets, limited sun exposure, heavy menstrual bleeding, recent pregnancy, known malabsorption (for example, coeliac disease), or long-term use of certain medicines may be more prone to low vitamin D, B12, folate, or related issues. Sudden onset shedding, scarring, or patchy loss warrants prompt clinical assessment as these patterns may point away from simple nutritional causes.

Dietary sources that support hair health - Vitamin D: oily fish (salmon, mackerel, sardines), egg yolks, fortified milks and spreads; sunlight exposure helps the body make vitamin D. - Vitamin B12: meat, fish, dairy; fortified plant milks and breakfast cereals for those avoiding animal products. - Folate: leafy greens, legumes, citrus, fortified grains. - Biotin: eggs (cooked), nuts, seeds, legumes. - Riboflavin: milk, yogurt, eggs, mushrooms, fortified cereals.

Safe supplementation and UK guidance - Vitamin D: Public health guidance in the UK advises most adults to consider 10 micrograms (400 IU) daily in autumn and winter. Some people may need different doses based on blood tests and medical advice. - Multivitamins: If diet is mixed and balanced, additional high-dose supplements are usually unnecessary. Avoid combining multiple products that duplicate nutrients, particularly vitamin A. - Testing in your area: GPs and community clinics can arrange blood tests and advise on safe, evidence-based dosing where correction is needed.

When hair loss is not about vitamins Common conditions such as androgenetic alopecia (pattern hair loss), traction from tight hairstyles, scalp inflammation, and autoimmune disorders can cause thinning independent of vitamin status. Stress, illness, and hormonal changes (for example, after childbirth) can also trigger shedding. Addressing these factors—alongside correcting any proven deficiency—offers the best chance of stabilising hair density over time.

Practical takeaways - Vitamin deficiencies can contribute to shedding, but they are only one part of a larger picture. Testing helps confirm whether a shortfall exists. - Vitamin D, B12, folate, riboflavin, and, rarely, biotin are the most relevant vitamins in this context. Excess vitamin A can worsen shedding. - Focus on a balanced diet, safe sunlight exposure, and targeted supplements only when indicated. Coordinate any plan with healthcare support to avoid interactions or unnecessary doses.

Conclusion Several vitamin deficiencies may be associated with hair thinning, but they are not the sole explanation for most cases. A careful evaluation, including diet, health history, scalp examination, and selected blood tests, helps distinguish nutritional factors from other causes. Correcting verified deficiencies and addressing non-nutritional triggers provides a measured, realistic approach to improving hair health over time.