Rosemary, Cedarwood & Sage Hair Thickener

Researchers at Cairo University found that women who were experiencing virgin hair loss also had lower levels of iron and vitamin D2—and hair loss only got worse as the levels dropped.

“This is the first time vitamin D’s possible role in hair loss has been highlighted,” explains Rania Mounir Abdel Hay, MD, a dermatologist at Cairo University, and co-author of the study. “It might regulate the expression of genes that promote normal hair follicle growth.” As for iron: Low levels may inhibit an essential enzyme that has been associated with hair loss in mice.

Aim for a minimum of 600 IU of vitamin D per day, virgin hair 800 IU if you’re over 71 years old. While it can be difficult to get enough vitamin D in your diet, salmon packs 450 IU per 3-ounce serving, and fortified milk and orange juice has 115 to 135 IU. And consider a vitamin D supplement, which has more than just healthy hair benefits: It could prevent heart disease, cancer, and bone fractures. Click here to find the best dose for you.