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Which Vitamin Deficiency Causes Hair Loss?

BY Felicia Ler

Disclaimer: The information provided is not intended as medical advice. For any medical concerns, always contact your doctor.

Hair loss can be a scary experience as you watch the clumps gather on your bathroom floor or get trapped between the bristles of your hairbrush. But because almost everything under the sun can trigger excessive shedding, it can be challenging to nail down the exact causes.

That said, nutritional deficiencies are a good place to start when demystifying the issue of increased hair fall. Even though hair fibers are made of dead cells, the hair follicles that give rise to hair fibers are very much alive and require proper nutrition to maintain a full head of healthy-looking tresses.

We’ll show you which vitamin deficiency causes hair loss so you can avoid these nutritional pitfalls. Spoiler alert: There’s more than one to watch out for.

The Different Facets of Hair Loss

Before we go a little deeper into the different forms of hair loss, you must first understand how the hair growth cycle works.

Your hair goes through three phases — growth, transitional, and resting — to create fully-formed hair strands. Unfortunately, external and internal factors may trip up your hair growth cycle at different stages, causing your mane to grow more slowly or not at all.

Here are a few common types of hair loss:

  • Androgenetic alopecia (AGA): Also known as female pattern baldness or female pattern hair loss, AGA begins with a receding hairline that may lead to baldness over time.
  • Alopecia areata (AA): This autoimmune condition occurs when the immune system mistakenly attacks the hair follicles. Hair loss may take place on the scalp, randomly, or all over the body.
  • Telogen effluvium (TE): This temporary form of hair loss happens when fewer follicles enter the growth phase with more follicles in the resting phase. The slower rate of new hair growth results in hair thinning, minus the baldness.
  • Anagen effluvium: Different from telogen effluvium, anagen effluvium happens during the growth phase of your hair cycle. Factors like chemotherapy affect the hair-growing abilities of the follicles.

Which Vitamin Deficiency Causes Hair Loss?

Not sure which vitamin deficiency causes hair loss? We scanned scientific literature to get answers on which nutrients are vital for hair health.

1. Vitamin D

Science explains that vitamin D plays an important role in stimulating hair follicular growth. This is evident from the increased activity of vitamin D receptors during the growth and transitional phases of the hair cycle.

As such, it’s no surprise that vitamin D deficiency is widely associated with various hair loss conditions — think telogen effluvium, androgenetic alopecia, and alopecia areata.

A 2018 systematic review and meta-analysis pored over 14 studies involving 1,255 patients with alopecia areata and 784 healthy individuals. It found that people with alopecia had substantially lower vitamin D levels than those without.

Another small-scale study of 80 women unveiled significantly lower vitamin D concentrations in those with telogen effluvium or androgenetic alopecia. The researchers also noted the vitamin levels diminished as hair loss worsened.

As these studies demonstrate, it’s in your best interest to consume enough vitamin D in your diet. Think fatty fish like salmon and tuna, egg yolks, as well as vitamin D-fortified cereals, milk, and juices. If necessary, try vitamin D supplements to meet your daily intake for this essential nutrient. Speak to your doctor before taking any supplements.

2. Vitamin E

A small study showed that those who already suffered from thinning hair could benefit from vitamin E supplementation.

Individuals who took 100 milligrams of vitamin E supplements every day for eight months witnessed a 34.5% increase in the number of hair strands versus the 0.1% decrease in those who didn’t.

The researchers explained that the antioxidant properties of vitamin E helped tackle the free radical damage and oxidative stress characteristic of most types of hair loss. Of course, more research is needed in this area to cement the association between low vitamin E levels and excessive hair shedding. But this study is promising.

3. Vitamin B2

Vitamin B2, also known as riboflavin, may cause hair loss if you don’t get enough of it. This micronutrient is necessary for numerous reasons, including cell development, fat metabolism, and energy production.

Even though vitamin B2 nutritional deficiency is uncommon in the United States, medications, alcohol, pregnancy, and breastfeeding put a dent in your body’s supply. Plus, this deficiency usually manifests as part of a generalized B vitamin insufficiency.

Health experts recommend upping your riboflavin intake with leafy greens like spinach, dairy products, and fatty fish.

4. Vitamin B7

A lack of vitamin B7 (or biotin) is another common cause of hair loss.

Per a 2017 systematic review, supplementation may be useful for poor hair growth and brittle nails due to biotin deficiency. That said, the review only covered 18 case reports, so more research is needed to see if biotin supplements will be equally beneficial to the general population.

Other Micronutrient Deficiencies Linked to Hair Loss

So far we’ve talked about which vitamin deficiency causes hair loss. But there are also other micronutrient deficiencies affiliated with excessive hair shedding that you should watch out for.

Vitamin A

This isn’t exactly a nutritional deficiency, but rather a vitamin oversupply. As it turns out, too much vitamin A consumption has been linked to hair loss, per the earlier 2019 review we mentioned.

The reason is that while vitamin A is proven to stimulate hair follicles in mouse and rat models, a 2012 review pointed out that “precise levels” are needed to strike the right balance between hair growth and shedding.


Iron deficiency (with or without anemia) is one of the most infamous causes of hair loss, especially among vegans and women with heavy periods. Iron is the raw material for making hemoglobin, which is the protein that helps carry oxygen to all cells in your body, including those in your hair follicles.

A 2010 medical review highlighted that there are “iron-dependent genes in the hair follicle bulge region that may be affected by iron deficiency.” That said, the review consists of mixed perspectives on whether iron deficiency causes hair loss.

To illustrate, a small study of 18 iron-deficient women benefited from hair regrowth after oral supplementation. Meanwhile, another study saw no significant difference in iron levels between people with hair loss and those without.

If you talk to your physician and decide to give iron supplements a go, pair them with vitamin C for best results. A 2019 review in the Journal of Dermatology and Therapy explained that vitamin C boosts iron absorption in the intestines for optimal intake of the mineral.

Essential Fatty Acids

Polyunsaturated essential fatty acids can cause your hair to fall out in earnest if you don’t consume enough of them.

The reason is that these fatty acids regulate the expression of androgen, a male sex hormone associated with hair loss. Plus, research shows that arachidonic acid, a type of omega-6 fatty acid, promotes hair growth.


Selenium deficiency causes hair loss, too. One study involving six selenium-deficient babies found that oral supplementation improved their symptoms. That said, this is a very small-scale study, and selenium insufficiency is usually quite rare for people who eat a balanced diet.

The Jury Is Still Out on These Nutrients

We haven’t spilled the entire cup of tea regarding which vitamin deficiency causes hair loss. There are a few other vitamins and minerals that may or may not be blamed for the increased hair fallout. Here’s what you need to know.

Vitamin B9

Vitamin B9 is commonly called folate (natural) or folic acid (synthetic). At the moment, scientific studies have mixed results on whether this nutritional deficiency thins out tresses.

To illustrate, a 2009 study demonstrated no significant differences in zinc, vitamin B9, and vitamin B12 levels between people with hair loss and those without. Meanwhile, a more recent 2017 study highlighted “a very high prevalence of folate deficiency” in individuals with female pattern baldness and telogen effluvium.

All in all, make sure you get enough folate in your diet to cover all your bases.

Vitamin B12

Vitamin B12 deficiency is often thought to be one of the causes of hair loss. After all, this micronutrient is needed for deoxyribonucleic acid (DNA) synthesis and red blood cell production, both of which are critical to growing new hair fibers.

Be that as it may, there’s currently no scientific data that links vitamin B12 deficiency to hair loss. While the jury is still out on this matter, it probably won’t do you any harm to regularly replenish your body’s B12 levels.

Stay On Top of Your Diet and Haircare Routine

Given the various nutritional deficiencies associated with sparse hair strands, it seems like healthy, balanced meals are the first hair loss treatment to consider. But as with everything in life, moderation is key. Take care to hit the daily requirements for the nutrients listed above without going overboard. And always consult a doctor, dietician, or nutritionist to build the ideal diet for you.

On top of that, a haircare routine specifically targeted at your unique hair needs will probably help enhance the appearance of healthy hair. That’s where Function of Beauty comes in handy. Leveraging 100% custom-made formulations, we help your locks look and feel their best. Take our hair quiz today.