5 minute read

Which vitamin deficiency causes hair loss?

By Ashton Sheriff | Medically reviewed by Dr Jaskirt Matharu

When we think about what causes hair loss, it’s tempting to blame male pattern baldness, stress, or destructive hair care products as the main culprits. But did you know that a poor diet can lead to hair loss, too?

Not getting enough nutrients in your diet can lead to vitamin deficiencies, which can cause (or worsen) hair loss in men and women. Considering nutrient-poor, processed food is “abundant and consumed on a regular basis” in the UK, vitamin deficiency hair loss is a very real risk for many Brits.

It’s important to maintain a healthy diet to support your general health - as well as to protect your hair. While there are a handful of effective hair loss treatments available today, it’s still vital that you eat well to reduce the chance of developing vitamin deficiency hair loss. 

Iron deficiency hair loss

Iron deficiency is the most common nutritional deficiency in the world. It’s well known that iron deficiency causes anaemia (a condition in which the body does not produce enough red blood cells) but you may be surprised to learn that it can also cause hair loss. 

It’s not yet fully understood how or why iron deficiency causes hair loss, but it can look similar to hair loss caused by other conditions such as male pattern baldness. 

People who are at risk of iron deficiency (and potentially iron deficiency hair loss) include:

  • Vegans and vegetarians (non-heme iron, found in plants, isn’t as bioavailable as heme iron, which is found in meat and fish).

  • Women who have heavy and/or prolonged periods (blood loss can reduce the amount of iron in the body). 

  • People with celiac disease or other conditions that prevent nutrients from food being absorbed properly. 

Regardless of whether you’re particularly at risk of iron deficiency or not, it’s important to measure your iron levels every so often with a blood test. If the levels of iron in your body are too low for too long then you could develop iron deficiency anaemia. This can lead to further health complications later on down the line, but these can be avoided by keeping an eye on your iron levels.

These days, blood tests can be taken at home using a home blood test kit without needing to see a doctor in person. This makes it much easier to manage your health in a way that’s convenient to you. Oh, and home blood tests are needle-free, meaning they’re ideal if you don’t like doctors pointing sharp, pointy objects at you. 

Of course, iron supplements are an option if you have a low iron status (or if you just want to support your iron levels in general). However, if you’re considering taking an iron supplement - or any other supplements - it’s always best to consult a clinician before taking it. Overdoing it with iron supplements can cause an upset stomach, nausea, and even organ failure if too much is taken, so it’s highly recommended that you only take iron supplements after speaking to a clinician. 

Zinc hair loss

Zinc is a wonderfully beneficial mineral that your body relies on for many vital processes. Not only does it help to support your immune system, but it also helps to heal wounds and plays a role in your senses of taste and smell. 

If you don’t get enough zinc in your diet, however, you may experience a type of hair loss called telogen effluvium. There are many causes of telogen effluvium, including severe trauma, illness, and extreme stress. However, zinc deficiency can also cause this kind of hair loss, which is characterised by abrupt hair shedding across the entire scalp.

Telogen effluvium occurs when the hair cycle is disturbed. Your hair naturally goes through a regular cycle of growth and shedding, but when this process is disrupted the proportion of your hair that enters the shedding phase may increase. If this happens, you may notice more hairs on your pillow than usual or more hairs around the plughole after taking a shower. 

People who have a higher chance of experiencing zinc deficiency include:

  • Vegetarians (as the bioavailability of zinc is lower in vegetables than meat) 

  • People with inflammatory bowel disease (or other conditions that prevent the nutrients from food being absorbed properly). 

  • People who have had gastric bypass surgery. 

  • Pregnant women. 

  • People with liver or kidney issues. 

  • People with alcoholism. 

There is some evidence to suggest that taking zinc supplements can help to correct a low zinc status.

Before taking any supplements, it’s always best to talk to a clinician to make sure it’s safe for you to take and won’t interact with any medication you’re taking. 

Vitamin D hair loss

Vitamin D - also known as the “sunshine vitamin” - helps to support normal bone health, muscle function, and a healthy immune system. The best source of vitamin D is natural sunlight, but you can also get vitamin D in your diet by eating things such as oily fish or certain types of mushrooms. 

While there isn’t much data to suggest there is definitely a link between vitamin D deficiency and hair loss, one study showed that women with female pattern hair loss and telogen effluvium (another type of hair loss) had lower vitamin D2 levels than the control group. 

People who may be more prone to low vitamin D levels are people who:

  • Spend a lot of time indoors (e.g. people who spend most of their day in the office).

  • Keep most of their skin covered by clothes when outdoors (e.g. due to cold weather or religious practices). 

  • Have darker skin (it takes people with darker skin longer to synthesise vitamin D). 

Regardless, the Department of Health and Social Care advises that anyone above the age of 4 considers taking a daily vitamin D supplement containing 10 micrograms of vitamin D during the autumn and winter. 


Biotin (vitamin B7) is known to contribute to the maintenance of normal hair and skin. However, biotin deficiency can lead to various conditions including alopecia - a type of hair loss that can cause hair thinning and hair loss on the scalp, as well as on other parts of the body (depending on the type of alopecia you have). 

There is currently no evidence that biotin can treat hair loss in people who don’t have a biotin deficiency. Luckily, biotin deficiency is rare because the intestinal bacteria we have are usually able to produce enough biotin to meet our needs. 

The numan take

Vitamin deficiencies are associated with hair loss in men and women. Low levels of iron, zinc, vitamin D, and biotin can all cause hair loss such as telogen effluvium and alopecia. In many cases, taking supplements alongside a balanced diet can help to correct a low vitamin status. Whether this will reliably lead to hair regrowth or stabilisation of hair loss, though, is debatable. 

Vitamin deficiencies are often hard to detect as the symptoms aren’t always obvious. For this reason, it’s recommended that you check your nutrient levels with a blood test to make sure they’re normal. 

If your nutrient levels are healthy but you’re still experiencing hair loss, you may benefit from hair loss treatment like a Hair Kit, which can contain minoxidil and/or finasteride, two hair loss treatments that have been clinically proven to be effective for 94% of men when combined.