Hair loss is common, but that doesn't make it any less distressing, especially for women. While thinning hair can be due to several causes, you shouldn't overlook the possibility that nutrient deficiencies or imbalances may be the culprit.
"A diet rich in minerals and vitamins can be beneficial for keeping hair growing thick and healthy," Lee Cotton, a registered dietitian in Stuart, Florida, tells LIVESTRONG.com.
Vitamin Deficiencies That Can Hurt Hair Health
Low blood levels of biotin, one of the B vitamins, can cause thinning hair, reports the U.S. National Library of Medicine. Good sources of biotin include egg yolks, soybeans, legumes, sardines, salmon, whole grains and nuts. If you're an adult aged 19 or older and getting 30 micrograms per day, that's considered adequate; for breastfeeding women, it's 35 micrograms, according to the National Institutes of Health's Office of Dietary Supplements (ODS).
However, a March 2019 review in Dermatology and Therapy, which examined studies of vitamins and minerals and their relationship to hair loss, says there isn't enough evidence to support supplementing with biotin to treat hair loss.
Read more: The 12 Best Foods for Healthy Hair
On the other hand, studies do show that supplementing with vitamin D may improve symptoms in two common types of hair loss affecting women — androgenetic alopecia and telogen effluvium, according to the authors of the March 2019 Dermatology and Therapy study. Likewise, there's a link between alopecia areata (a skin disorder causing hair loss) and low vitamin D levels, which is one of the reasons people should take a supplement if their levels of the "sunshine vitamin" are low, the study authors say.
The recommended daily allowance of D for most adults is 15 micrograms or 600 international units, according to ODS. Vitamin D-fortified foods — typically including cereals, orange juice, cow's milk and soy milk — and, to a lesser extent, eggs and cheese and sunlight, are all sources of vitamin D, the NIH's supplements office notes.
In the case of vitamin A, too much of a good thing can spell trouble for your hair, according to the American Academy of Dermatology. High doses of this water-soluble vitamin — usually the result of over-supplementing — can contribute to hair loss.
Mineral Deficiencies That Can Weaken Your Locks
Deficiencies in certain minerals, most notably iron and zinc, can also cause thinning hair and hair loss in women, according to a January 2017 literature review in the journal Dermatology Practical and Conceptual.
Women ages 19 to 50 require 18 milligrams of iron daily, pregnant women need 27 milligrams and women over age 50 need 8 milligrams of iron per day, according to ODS.
Those with androgenetic alopecia and telogen effluvium who have low iron levels may benefit from taking supplements, according to authors of the March 2019 review in Dermatology and Therapy, although more research is needed on this topic.
Zinc requirements for women are 8 milligrams daily, with 11 milligrams suggested during pregnancy, says ODS.
Iron- and zinc-rich foods include meat, poultry, seafood, legumes and fortified breakfast cereals. Dairy foods are also good sources of zinc. A 4-ounce portion of lean ground beef provides about 3 milligrams of iron and 6 milligrams of zinc.
There's insufficient evidence to recommend zinc supplementation in those who are deficient in this mineral and more studies are needed to determine whether iron and zinc supplementation makes a difference in treating alopecia areata.
Macronutrients for Shiny Tresses
Eating too few calories and getting too little protein and dietary fat — especially essential fatty acids, which are fats your body requires daily — can also contribute to thinning hair and hair loss in women.
"Protein is an essential macronutrient for hair," explains Cotton. "In fact, the structure of hair is comprised of keratin, a hardened protein."
Healthy fats, such as those found in cold-water fish, contain hair-strengthening omega-3s. "Those fatty acids aid in hair strength and luster," confirms Cotton.
Moderately active women should consume 1,800 to 2,200 calories daily. For a 2,000-calorie-per-day diet, 44 to 78 grams per day (or 20 to 35 percent) should come from healthy fats. Nuts have about 12 to 14 grams of healthy fats per ounce, and plant-based oils, like olive oil, provide 14 grams per tablespoon.
The recommended daily allowance of protein for women is 46 grams, according to the Institute of Medicine. Cottage cheese provides about 14 grams per 1/2 cup. One cup of black beans offers about 15 grams, while grilled chicken breast has about 26 grams per 3-ounce serving.
Of course, making sure your diet contains the optimum amounts of these nutrients is always a good idea. It yields dividends that go way beyond a lush head of hair.
If you're certain you're not lacking in key nutrients, and are still noticing thinning hair, it's wise to consult with your doctor or a dermatologist, who can help you get to the root of the problem.
- American Academy of Dermatology: "Hair Loss"
- National Institutes of Health Office of Dietary Supplements: "Vitamin D"
- Dermatology Practical and Conceptual: "Diet and hair loss: effects of nutrient deficiency and supplement use."
- National Institutes of Health Office of Dietary Supplements: "Iron."
- National Institutes of Health Office of Dietary Supplements: "Biotin."
- National Institutes of Health Office of Dietary Supplements: "Zinc."
- Institute of Medicine: "Dietary Reference Intakes:Recommended Dietary Allowances and Adequate Intakes, Total Water and Macronutrients
- Dermatology and Therapy:"The Role of Vitamins and Minerals in Hair Loss: A review."