September 2017 Issue

Hair Growth Supplements
By Jessica Levings, MS, RDN
Today's Dietitian
Vol. 19, No. 9, P. 40

A plethora of supplemental nutrients and botanicals boast claims to regrow hair and restore hair health, but are they evidence based?

Alex always took pride in having a full head of thick hair. Her hair grew quickly whenever she trimmed or cut it. She could style it any way she wanted to with the use of a blow dryer, curling iron, or flat iron. She could color and relax her hair, and it remained healthy and strong. However, after many years of doing this, she began losing hair that didn't grow back. To stop the hair loss and promote healthy hair growth, she stopped getting relaxers and heat styling her hair and began using products to help stimulate hair growth, and started taking hair growth supplements in hopes of restoring what was lost. After several months, some, but not all, of her hair grew back. But the overall health of her hair began to improve.

Hair loss is a common condition, affecting about 80% of men and 50% of women.1 Manufacturers have responded to growing concerns over hair loss, and, as a result, hair care has become the largest segment of the $56.2 billion beauty industry, with 24% of market share by revenue.

Many oral supplements and topical solutions marketed as hair loss treatments are available online and over the counter and claim to produce benefits such as healthy hair and sustained growth. To someone with thinning hair, this may sound enticing, but these supplements aren't risk-free. Online and over-the-counter hair growth supplements don't need FDA approval before reaching shelves and scalps,2 and, according to the FDA, each company is responsible for ensuring that "the products it manufactures or distributes are safe" and that any claims "are not false or misleading." Furthermore, excessive intake of certain vitamins and minerals, such as selenium and vitamin A, has been linked to hair loss,3-7 and, since the quantity of ingredients contained in supplements isn't regulated, it's hard to know how much the consumer is actually getting.

Common causes of hair loss include one or a mixture of the following:

• heredity (also known as male or female pattern baldness, and androgenetic alopecia);
• underlying disease state (such as thyroid disease or anemia);
• hormones and stress;
• medications (eg, blood thinners; medications for arthritis, depression, gout, heart problems, and high blood pressure; some birth control pills; anabolic steroids);
• diet (eg, excessive vitamin supplementation, insufficient protein or iron, rapid weight loss, eating disorder or fad dieting leading to nutrient deficiencies);
• hair hygiene (excessive shampooing, combing, or brushing; heat styling; relaxers; tightly braided hair styles; rubbing wet hair with a towel; and brushing or combing wet hair); and
• life stage (pregnancy, breast-feeding, and menopause).

Over-the-counter hair loss products and supplements may seem ubiquitous, but they're not created equal. The FDA has approved only one topical product (sold over-the-counter and online) proven to treat hair loss in men and women. Minoxidil (sold under brand names such as Rogaine, Theroxidil, Re-Stim, and Re-Stim+) is a topical scalp application that stops hair from thinning while stimulating growth. It's effective in approximately two out of three men and one out of five women and is most effective for people younger than 40 who've recently started experiencing hair loss. However, it doesn't cure the root cause of hair loss. Users must continue to apply it or they'll experience hair loss again.

Research Summary
Online and over-the-counter hair growth supplements range in price from nominal to expensive. But do these products work, and are they worth the money?

According to a 2017 study, "While such products contain a variety of nutrients, review of the medical literature finds a notable lack of evidence supporting their use." The study goes on to mention that much of the evidence about the relationship between nutrients and hair loss is based on people with an underlying nutrient deficiency, and few studies have looked at hair growth supplementation in individuals without nutrient deficiency.2

Furthermore, findings from the limited data that exist vary, with some looking at the effect of one nutrient alone and others analyzing a group of nutrients in combination. For example, a 2013 observational study found that women experiencing hair loss had significantly lower levels of serum vitamin D compared with women not experiencing hair loss.8 A 2015 study evaluated supplementation with omega-3 and omega-6 fats, along with other antioxidants, and found that subjects reported a significant increase in hair regrowth and hair diameter after six months.9 Similarly, while some products target one nutrient, such as biotin, newer supplements and products claim a multifactorial effect and include many active ingredients.

Hair growth products commonly include the following ingredients and claim they promote normal, healthy hair, but limited evidence supports these benefits in the absence of a nutrient deficiency. Listed below are nutrients and botanicals and their related claims made by manufacturers. Only the claims with references are associated with publicly available research findings, none of which provide adequate evidence for RDs to recommend these supplements to clients in the absence of an underlying nondiet-related nutrient deficiency (eg, medication, stage of life, or illness).

Protein and Amino Acids
Methionine is an essential amino acid, and products touting this ingredient say it works by providing adequate amounts of sulfur to hair cells, aiding in growth and appearance including delayed graying.10,11

Cysteine is a sulfur-based amino acid and an important part of keratin, which contributes to healthy hair structure and growth. Products touting this ingredient claim to support hair strength (and thus prevent loss) by providing sulfur.12,13

Lysine is an essential amino acid touted as aiding hair growth when combined with other amino acids, specifically arginine. Products with lysine claim to promote healthy hair growth through aiding hormone secretion and immune function.

Keratin is a protein that serves as a structural component of hair and contributes to healthy hair growth.

Vitamin A helps with hair growth by maintaining healthy follicles. Products high in vitamin A claim to contribute to thicker, longer hair.14,15

Vitamin C helps produce and maintain healthy collagen levels within hair follicles. It's also an effective antioxidant helping to reduce free radical and UV damage to follicle cells and collagen.

Vitamin E helps support cell membranes and also is a powerful antioxidant that reduces the effect of free radicals on hair, especially when consumed with selenium.16,17

B vitamins are common in hair growth supplements and offer a range of benefits to hair health.18 Niacin (B3) can improve blood flow and increase the delivery of nutrients to hair follicles, supporting hair growth. Pantothenic acid (B5) increases hair flexibility, strength, and shine and helps prevent hair loss and graying. Pyridoxine (B6) aids in the metabolism of amino acids required for hair growth.

Biotin (B7) is needed for protein, fat, and carbohydrate metabolism; a deficiency can lead to poor metabolism of nutrients and undernourished hair follicles over time. While clinical studies suggest that a biotin deficiency, while rare, can lead to severe hair loss, there's no evidence supporting the role of biotin supplementation in the prevention of hair loss when biotin is consumed in adequate amounts in the diet.19,20 People with adequate protein intake shouldn't experience a biotin deficiency or hair growth-related side effects of a biotin deficiency.

Folic acid (B9) stimulates growth of new hair, and inadequate amounts can lead to reduced hair follicle cell division and growth. Cobalamin (B12) aids in overall scalp health. Inadequate levels of thiamin (B1), riboflavin (B2), niacin (B3), and pantothenic acid (B5) allegedly can lead to undernourished, dull hair follicles.

Iodine helps maintain healthy thyroid function. A deficiency can lead to thyroid disorders as a cause of hair loss.21,22

Zinc contributes to stronger hair structure and can improve the rate of hair growth. Zinc deficiencies have been linked to hair loss; products touting zinc claim to help reverse hair loss.23

Iron levels have been linked to hair loss, with research suggesting that many women who experience hair loss have low levels of blood iron.24,25

Selenium, a trace mineral that aids in iodine metabolism and thyroid function, protects hair follicles through its role as an antioxidant. Products claim selenium supports hair growth through its role in maintaining the thyroid.26

Copper helps other enzymes function properly in the body, supports healthy blood flow, and acts as an antioxidant to prevent hair loss. Emerging research suggests copper might stimulate the production of new hair follicles.27,28

Manganese is a silica-rich mineral aiding in the production of connective tissue and collagen, both of which are important for healthy hair development. Silica occurs in trace amounts in the diet, but many forms aren't bioavailable. Foods rich in manganese can help provide adequate silica.29,30

Resveratrol protects the follicles and scalp against inflammation and oxidative stress caused by free radicals. Resveratrol also helps improve blood circulation, providing sufficient oxygen and enhancing the development and growth of hair follicles.

Fatty Acids
Polyunsaturated fatty acids, such as omega-3 and omega-6 fatty acids, help with the appearance of hair and reduce dry, scaly skin.

Gamma-linoleic acid commonly is consumed in supplement form as borage oil. Products claim it supports hair growth by reducing inflammation in the skin and scalp and helping to retain moisture.31,32

Saw palmetto is sometimes referred to as "The Natural Rogaine" because its compounds help prevent the shrinking of hair follicles, which can lead to hair loss.33,34

Ginkgo biloba has been shown to increase the growth rate of follicle cells and improve circulation, which increases blood flow to the scalp and enhances nutrient delivery.35,36

Role of Diet and Food
While the exact cause of hair loss usually isn't clear, many times it's associated with an underlying nutrient deficiency.2 Products claiming to improve hair growth and prevent hair loss tout specific nutrients to support their use, but RDs understand that an inadequate eating pattern can't be fixed with supplements. Furthermore, topical solutions won't impact a nutrient deficiency, so the application of products containing Minoxidil won't improve nutrient intake or treat the cause of the hair loss.

If a client presents with concerns about hair loss or questions about hair loss supplements, many times their eating patterns are at the root of the concerns. Clients eating too little fat could be at risk of nutrition-related hair loss due to inadequate intake of essential fatty acids. Furthermore, individuals consuming inadequate amounts of protein could be at risk of nutrition-related hair loss from B vitamin deficiencies.

Similarly, clients eating too few calories may have a zinc deficiency. Fad diets with rapid weight loss can affect the normal hair growth cycle, causing increased shedding within six to 12 weeks upon initiation.

In the absence of an underlying disease state, a healthful, balanced eating pattern can be sufficient to prevent nutrient deficiencies and provide adequate amounts of nutrients to protect hair without the need for supplements specifically marketed for hair growth.

Recommendations for Clients
RDs faced with questions about hair growth supplements or concerns about hair loss should suggest clients talk with their doctor or dermatologist, if they haven't already, to diagnose the root cause of hair loss. Counseling related to consuming a healthful eating pattern with a variety of foods also is important. When presented with concerns about hair loss, it's important to review client food intake data to ascertain whether the eating pattern and nutrient intake is adequate.

Most nutrient-related causes of hair loss can be prevented with a balanced eating pattern. However, for clients wanting to take a hair growth supplement or begin using a topical solution or product, it's important to remind them that the supplement should be taken only in the dosage provided. Excess supplementation can, in some cases, exacerbate hair loss, and the exact quantity of ingredients contained in supplements isn't regulated.

Counseling for lifestyle-related risk factors, such as stress, in addition to diet also is important. Clients concerned that a medication may be contributing to hair loss should be encouraged to continue taking the medication at the dosage provided and make an appointment to talk with the prescribing doctor about their concerns.

A balanced eating plan similar to the Mediterranean diet consisting of lean protein sources, fruits, vegetables, whole grains, legumes, fatty fish, and low-fat dairy products is important for hair and overall health. Remember that clients don't always readily know food sources of specific nutrients affecting hair health; providing this information can help. (See table on page 43.)

A variety of fatty cold-water fish such as salmon and mackerel, as well as ground flaxseed, macadamia nuts, and walnuts, can provide omega-3 fatty acids, protein, vitamin B12, and iron. Legumes are a plant-based source of protein that also contain iron, zinc, and biotin. Good sources of biotin include cereal grain products, liver, egg yolk, soy flour, and yeast. Nuts contain high amounts of selenium, and some nuts, such as walnuts, also contribute alpha-linoleic acid and zinc. Zinc also can be found in fish oil, flaxseed, meat, eggs, and seafood such as oysters. Dark green leafy vegetables can provide iron and calcium, and dairy products also are good sources of calcium. Orange vegetables such as carrots are an excellent source of vitamin A.

Clients should be encouraged to seek out hair loss supplements and topical products that have ingredient lists readily available. Also, the products should be from manufacturers engaging in Good Manufacturing Practices. For clients who insist on using a hair growth product, RDs should recommend a supplement over a topical solution, since this will help increase nutrient intake.

Bottom Line
Data are scant associating hair growth supplements with the benefits they purport to convey. Consuming a balanced diet should prevent deficiencies associated with nutrient-related hair loss, but, in some disease states and life stages, a supplement may be needed. If clients feel they must consume a supplement to aid in hair growth, a basic one-a-day vitamin most likely will offer the same benefits at a fraction of the cost of over-the-counter and online hair growth supplements.

— Jessica Levings, MS, RDN, is a freelance writer and owner of Balanced Pantry, a consulting business helping companies develop and modify food labels, conduct recipe analysis, and create nutrition communications materials. Learn more at, Twitter @balancedpantry, and


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