Vitamins and supplements that promise hair growth almost sound too good to be true. Can taking a pill once or twice a day really make your hair longer, stronger and healthier?

Hair loss or thinning hair can be caused by a variety of culprits—including nutrition deficiencies. So while vitamins and supplements are not a miracle cure by any means, the right ones just might make a difference in the way your hair looks and feels.

What Are the Best Vitamins for Hair Growth?

Hair growth and healthiness are influenced by a number of factors, including nutrition, genetics, medical conditions, hormones and even stress. Research finds that a deficiency in vitamins and minerals important for normal cell growth and function may contribute to hair loss^[1].

“Vitamins are essential for healthy hair growth and may help in preventing hair shedding and thinning,” says Michele Green, M.D., a cosmetic dermatologist in New York. “The best vitamins for hair growth include B vitamins, vitamin D, vitamin E, zinc, biotin and iron.

Vitamin B

Complex B vitamins play a role in hair growth, and are “essential for metabolism and nervous system function,” says Dr. Green. “It is no wonder that B vitamins like vitamin B7 (biotin) and B12 are important to strengthen and condition the hair.”

Research shows you can easily reach the daily allowances of B vitamins by eating a balanced diet. B vitamins can be found in a variety of foods, including 100% whole grains, meat, fish, whole eggs, nuts and avocados.

Biotin

Biotin, also known as vitamin B7, is a complex B vitamin that is often touted for having hair growth benefits. And some of that hype may actually be worth it. Biotin has functions in “creating red blood cells, which carry oxygen and nutrients to the scalp and hair follicles,” says Dr. Green. It also “plays a role in keratin production, which is a main component of hair.”

Most people receive enough biotin from the foods they eat, notes the National Institutes of Health. The best way to get more is to eat biotin-rich foods. Dr. Green recommends milk, eggs, bananas, salmon, sweet potatoes and almonds. If you do feel you need an extra boost, talk to your doctor—supplement labels reveal that many biotin supplements for hair, skin and nails far exceed the recommended daily amount.

Vitamin C

Vitamin C isn’t only good for maintaining immunity, it may also make hair stronger. Dr. Green notes that as a powerful antioxidant, vitamin C is essential for healthy hair growth. “Vitamin C helps increase blood circulation throughout your body, including your scalp,” she says. “When there is increased blood circulation to your scalp, there is greater stimulation of your hair follicles, which may help promote hair growth.”

Iron

Iron plays a surprisingly important role in hair growth, too, and research in the Journal of Korean Medical Science suggests a link between iron deficiencies and hair loss among women. This micronutrient boosts circulation and helps move oxygen to your cells more efficiently, explains Dr. Green, which may aid in hair growth. “If you do not get enough iron, your body cannot produce sufficient hemoglobin, which will falter oxygen delivery to your scalp and contribute to hair loss,” she says.

She recommends eating foods high in iron, such as clams, red meat, spinach and lentils. An iron supplement may also be worth adding to your routine if you are at risk of iron deficiency, but check with your doctor first.

Keratin

Keratin is a protein that makes up our hair, skin and nails, notes Dr. Green. It’s naturally produced by the body, and there are many keratin supplements out there that claim to help with hair growth. However, Dr. Green suggests “supplementing” with keratin in a more natural way—by eating protein-rich foods like eggs, beans, fish and meats—rather than taking a pill. “There are no reliable studies that show keratin helps with hair growth,” she says. “Additionally, over-supplementing keratin can be harmful due to excess protein buildup in the body.”

Vitamin D

A deficiency in vitamin D may result in hair loss, according to Dr. Green. “Vitamin D is metabolized in the skin by keratinocytes, skin cells that produce keratin,” she says. “When the body does not have enough vitamin D, the keratinocytes in hair follicles have trouble facilitating hair growth, resulting in shedding and hair loss.”

Zinc

Zinc is a trace mineral and only needed by the body in small amounts. It’s small but mighty, and plays a role in everything from the growth of cells to creating DNA. “Low levels of zinc have been associated with hair loss and poor wound healing,” says Dr. Green. She recommends eating zinc-rich foods, like meat, beans, nuts and seeds.

If you struggle with hair loss or hair thinning, it also might be worth talking to your doctor about whether a zinc supplement could be right for you. One small study found that zinc supplementation should be given to alopecia patients who have a low serum zinc level^[3].

Vitamin A

Vitamin A might help with hair growth, but there’s a catch: taking too much of it might actually result in hair loss. Vitamin A refers to a group of compounds that include retinol, retinal, retinoic acid and provitamin A carotenoids, explains Dr. Green. “There has been a study involving mice that showed dietary vitamin A activated hair follicle stem cells,” she says. “However, this is complex…on the contrary, there has been evidence that high levels of vitamin A through over-supplementation is linked to hair loss.”

She notes that while vitamin A deficiency can contribute to hair loss, it’s not common in the U.S, adding that unless you have proof of a vitamin A deficiency, there’s no reason to supplement.

Eating foods rich in vitamin A may be better, she says, including leafy greens like kale, spinach and broccoli, orange vegetables like carrots, pumpkin and sweet potatoes, and yellow vegetables like squash.

Other Natural Ways to Stimulate Hair Growth

The above vitamins and minerals aren’t the only way to improve your hair health; Dr. Green notes that some oils, like rosemary and coconut oil, may also help with hair growth. A study found that consistent use of rosemary oil over several months led to an increase in hair count^[4].

Meanwhile, another study that compared coconut oil to mineral oil and sunflower oil found that coconut oil was the only one that reduced the protein loss for both undamaged and damaged hair when it was used as a pre-wash and post-wash treatment^[5].

Do Hair Growth Vitamins Work?

Certain vitamins and supplements may promote hair growth and healthiness in individuals who have nutritional deficiencies. This is because research suggests deficiencies in vitamins and minerals such as zinc, iron and vitamin D are linked to hair loss. More research is needed to determine the efficacy for hair growth supplements in individuals without nutritional deficiencies.

Top Supplements for Hair Growth, According To Experts

In addition to a diet that’s rich in all the vitamins and minerals that can impact hair growth, there are an array of over-the-counter supplements specifically geared toward those struggling with hair thinning or hair loss. As with any supplement, though, be sure to speak with your doctor.