by Jack Norris, RD
Occasionally, women who become vegetarian or vegan report experiencing hair loss. If there is a dietary cause, the most likely are rapid weight loss, thyroid problems, or iron deficiency (although this has more recently been questioned; see below). Zinc deficiency and not getting enough of the amino acid lysine could also be culprits.
Hair loss among women is not an unusual problem. In one study, 34% of women from Japan, the USA, and the UK reported increased hair loss compared to 5 years earlier. The reasons for hair loss are complicated and can vary from person to person. Thus, it is important to see a doctor who can diagnose the specific problem.
Hair Loss and Nutrition
In some cases, hair loss can be diet-related. Hair loss sometimes occurs in rapid weight loss. In one study, hair grew back within a few months after weight loss. In other cases, there are less obvious nutritional reasons for hair loss.
According to Mayo Clinic, an overactive or underactive thyroid gland can lead to hair loss. Upon going vegetarian or vegan, people might increase their soy intake. Soy can affect the thyroid, especially when iodine levels are not adequate or someone has mild thyroid problems. Making sure you get enough iodine, by taking 75 to 150 µg per day from a supplement, should prevent any hair loss problems that could be due to iodine or soy. If you have a mild thyroid condition, limiting soy might also help. If you take synthetic thyroid hormone, speak to your doctor about a healthy amount of soy.
In 2002, Dr. DH Rushton, of the University of Portsmouth in the UK, wrote a comprehensive review article on hair loss, a summary which follows (Rushton, 2002).
Hair loss can be divided into two categories: Hair loss with skin shedding (also called “scaling”) and hair loss without skin shedding. Hair loss with skin shedding is likely related to a skin disorder. In some cases, supplementation with the vitamin biotin (1 – 2 mg for 2 months) has helped. Essential fatty acids (omega 3s and/or omega 6s) might also help in hair loss caused by skin conditions.
There is a lack of objective data about hair loss without skin shedding. At one time, there was a widespread belief that zinc deficiency is a common cause. However, zinc supplementation has not been shown to improve hair loss, even when a deficiency is suspected. One area that seems clear is that iron deficiency (a low serum ferritin without anemia) is linked to hair loss in women. In one study, 72% of women with low iron stores (a serum ferritin less than 40 mcg/l) had reduced hair density.
The amino acid L-lysine plays a part in the absorption of iron and zinc. Among plant foods, L-lysine is only found in high amounts in legumes, and a vegan who doesn’t eat many legumes could find themselves falling short on lysine. In some women, iron supplementation does not lead to an increase in iron stores. But in one study, adding L-lysine (at 1.5 – 2 g/day for 6 months) to iron supplementation in such women did increase iron stores and decreased hair loss by one half.
Dr. Rushton noted the following odds and ends:
- In a multivitamin, if the level of zinc is equal to the level of iron, then iron uptake is significantly decreased. A ratio of 3 to 1, iron to zinc, is desirable to prevent competitive interference.
- Excessive vitamin E supplementation (for example, 600 IU per day for 1 month) can adversely affect hair growth. In patients with hair loss who show high levels of folic acid (also known as folate), excessive folic acid supplementation should probably be discontinued.
- Reducing the frequency of shampooing does not help preserve hair and can increase the fear of hair loss because a higher amount of hair will be lost all at once when it is washed.
Although studies looking at iron deficiency in women with hair loss have been somewhat mixed, a 2010 well-controlled study found no difference in rates of iron deficiency or anemia between women with hair loss and controls (Olsen, 2010). It is possible that iron deficiency plays a role in hair loss for some women, but it is unlikely to be a primary cause in most cases.
Olsen, 2010. Olsen EA, Reed KB, Cacchio PB, Caudill L. Iron deficiency in female pattern hair loss, chronic telogen effluvium, and control groups. J Am Acad Dermatol. 2010 Dec;63(6):991-9. Epub 2010 Oct 13.
Rushton, 2002. Rushton DH. Nutritional factors and hair loss. Clin Exp Dermatol. 2002 Jul;27(5):396-404.
6 thoughts on “Hair Loss”
You write ‘If you are predisposed to thyroid problems’, how does one test for this? How does one find out if they’re predisposed or not?
I updated the article; I hope it makes more sense. The only way to know for certain if you have thyroid problems is to have a doctor test your thyroid status.
You recommend 2 g of L-lysine for 6 months and iron at 3 to 1 ration to zinc. For an average size woman of 145 lbs what is dosage of iron you suggest. Thank you.
Iron needs depend on age and sex, not weight. The DRI for iron for women ages 19-50 is 18mg. It goes down to 8mg after that assuming menopause has taken place and iron is no longer being lost in menstrual blood.
If zinc reduces iron absorption, should individual supplements be taken separately (at different times of day)?
Some studies show that iron and zinc supplements interfere with each others absorption; some show no effect (1). No minerals are fully absorbed and taking supplements together won’t reduce absorption to zero. But if you believe you need to maximize absorption,then taking iron and zinc supplements separately would be most effective. Even taking supplements as little as 30 to 60 minutes apart seems to be enough to avoid interference with absorption (2). Iron supplements aren’t necessary unless you have iron deficiency or another condition requiring iron supplementation.
1. Bjørklund G, Aaseth J, Skalny AV, Suliburska J, Skalnaya MG, Nikonorov AA, Tinkov AA. Interactions of iron with manganese, zinc, chromium, and selenium as related to prophylaxis and treatment of iron deficiency. J Trace Elem Med Biol. 2017 May;41:41-53.
2. Olivares M, Pizarro F, Ruz M.New insights about iron bioavailability inhibition by zinc.Nutrition. 2007 Apr;23(4):292-5.