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Many supplements market themselves as the best for hair growth. But do any of them work?
Research on the benefits of supplements for hair growth has found mixed results. Nutrition as a whole is critical to hair growth. However, specific vitamin and mineral supplements may be necessary in some cases to correct nutritional deficiencies associated with hair loss.
This article discusses how much zinc you need daily for hair growth and whether supplements may be appropriate.
Zinc for Hair Growth
Supplement use should be individualized and checked by a health care professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or health care provider. No supplement is intended to treat, cure or prevent disease.
Zinc is a mineral that the body needs in small amounts (micronutrients). Zinc aids in immune function, cell turnover, and wound healing.
Zinc helps keep hair healthy by supporting the hair follicle cycle. Hair loss (alopecia) is a symptom of low zinc levels, and some research suggests that zinc supplementation can promote hair regrowth in people with hair loss. Zinc supplements may reduce hair loss by bringing low levels of the nutrient into the normal range. However, not all research supports this.
There is some evidence to support 50 milligrams (mg) of zinc supplements to reduce hair loss. One study in women with hair loss found that 50 mg of zinc daily improved hair thickness.
Another study among women with normal zinc levels and polycystic ovary syndrome (PCOS) observed less hair loss in women who consumed a zinc supplement of 50 mg daily for eight weeks than those who took a placebo (an ineffective substance called for a control group). Hair loss can be a side effect of PCOS.
Ultimately, there is not enough information to support zinc supplementation to prevent or reverse hair loss in people who do not have low levels or underlying health issues related to zinc status.
Hair from hand comb.
buakkarademir / Getty Images
Nutrition
The average daily amount of zinc necessary to meet nutrient requirements for most healthy adults (recommended dietary allowance, or RDA) includes the following:
Zinc can be obtained through food. It is found naturally in meat, fish and seafood and is added to many breakfast cereals. Foods with the highest amount of zinc include:
- Oysters: 32 mg per 3 oz
- Beef: 3.8 mg per 3 oz
- Breakfast cereals and oats: 2.3 mg per cup
- Pumpkin seeds: 2.2 mg per ounce
You only absorb between 5% and 50% of the zinc in food. This amount can vary depending on the food source of the zinc and the composition of the meal.
Plant-based foods are lower in zinc than their animal counterparts. In addition, certain substances found in plants (phytates) affect zinc absorption. Therefore, it can be more challenging to absorb zinc with a plant-based diet.
Zinc deficiency is less common in the United States, as most people meet requirements through food or supplements. Inadequate zinc levels are more common in low- and middle-income countries.
Safety
Zinc supplementation can do more harm than good, especially if you take too much. Always consult a healthcare provider before starting a new supplement.
In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. When choosing a supplement, look for third-party products that have been tested and consult with a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
Precautions
Avoid zinc if you are allergic to it or its component(s). Get medical attention immediately if you have a serious allergic reaction (itching, hives, shortness of breath).
People with Wilson’s disease (hepatolenticular degeneration, a condition of excess copper) A health care provider should be consulted before starting zinc supplements.
- The Food and Nutrition Board (FNB) at the Institute of Medicine (IOM) decided the upper limit of acceptable intake for zinc at 40 mg per day for all adults, including those who are pregnant or lactating
The tolerable upper limit (UL) represents the maximum daily amount that a person can take without risk of adverse health effects for most individuals.
The FNB does not recommend taking doses of 50 mg zinc or more for a long period of time. Excess zinc can affect copper absorption and reduce immune function.
Side effects
Too much zinc can cause adverse effects. Although it is difficult to exceed recommendations through diet alone, toxicity is possible with zinc supplements.
Side effects include the following:
Long-term side effects such as reduced immune function are also possible.
Excessive zinc supplementation can also affect the absorption of other vital micronutrients such as copper and iron.
Interactions
Zinc may interact with certain medications, and medications can affect zinc levels. These medicines include:
- Antibiotics: Antibiotics treat or prevent bacterial infections. Some antibiotics may interact with zinc supplements in the digestive tract, affecting the absorption of both medications.
- Cuprimin (penicillamine): Penicillamine removes high levels of heavy metals from the body. It can treat rheumatoid arthritis and Wilson’s disease, a condition where copper levels in the body are too high. Zinc supplements may lower the absorption and effect of penicillamine. Taking zinc and penicillamine at least an hour apart may reduce this interaction.
- Diuretics: Diuretics prevent accumulation and help remove excess fluid from the body. Specific types of diuretics can increase zinc removal through urine, contributing to lower nutrient levels.
It is essential to carefully read a supplement’s ingredient list and nutrition facts panel to find out which ingredients and how much of each ingredient is included. Review the supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.
Similar Supplements
Other nutrients contribute to healthy hair. However, limited research supports taking these supplements for hair growth unless you are deficient in these nutrients.
Protein
Hair consists primarily of protein. Not eating enough protein can contribute to hair loss.
It is not clear whether supplementation with a specific amino acid (protein molecule) can improve hair loss. Much research on amino acids also includes other nutrients, so it is difficult to draw a clear link between individual amino acids and hair loss.
The RDA for protein is at least 0.8 grams (g) of protein per kilogram (kg) of body weight (g/kg). However, some individuals may need more protein.
Foods rich in protein include:
- Animal meat
- Seafood
- Dairy
- Tofu
- Tempeh
- legumes
Iron
Hair loss is related to iron levels. Hair cells are among the most active in the body and require adequate levels of iron to function properly. However, there is little evidence to support the benefits of iron supplements for hair growth without having low iron levels.
The FNB at the IOM of the National Academy recommends the following daily iron intake in adults:
- 8 mg for men
- 18 mg for women aged 19 to 50 years
- 8 mg for women older than 51
- 27 mg for pregnant women
- 9 mg for lactating people
Food sources of iron include lean meat, seafood, and fortified cereals and grains.
Omega-3 fatty acids
Omega-3 fatty acid deficiency is associated with hair and eyebrow loss. One randomized controlled trial among women with hair loss found a supplement containing 460 mg of fish oil (a source of omega-3 fatty acids) reduced hair loss and improved hair thickness. But the supplement also contained antioxidants, which is a weak fish oil, and the additional antioxidants may have contributed to the beneficial results.
There is no set recommended dietary allowance for omega-3 fatty acids. However, adults are recommended to consume the following amounts of omega-3 fatty acids daily to ensure nutritional adequacy:
- 1.6 g for men
- 1.1 g for women
- 1.4 g for people who are pregnant
- 1.3 g for lactating people
Foods rich in omega-3 fatty acids include:
Summary
If you are concerned about hair loss, talk to a health care provider to help identify the root cause.
A healthy diet with plenty of nutrients and protein provides the best support for hair growth. Sometimes, a nutritional deficiency may contribute to hair loss. If you have low zinc or iron levels, supplementing may help restore nutrient levels and promote hair growth. But if your levels of these minerals are already within a normal range, then supplementation is unlikely to support hair growth or prevent hair loss.
Taking zinc when it is not needed can do more harm than good, contributing to unwanted side effects and interfering with the absorption of other minerals essential to health.
