Many supplements promote themselves as being best for hair growth. But do any of them work?
Research into the benefits of hair growth supplements has yielded mixed results. Nutrition as a whole is vital for hair growth. However, specific vitamin and mineral supplements may be warranted in some cases to correct nutritional deficiencies associated with hair loss.
This article explains how much zinc you need daily for hair growth and whether supplements may be appropriate.
Zinc for hair growth
Use of supplements should be individualized and approved by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare professional. No supplement is intended to treat, cure, or prevent any disease.
Zinc is a mineral that the body needs in small quantities (micronutrients). Zinc contributes to immune function, cell renewal 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 may promote hair regrowth in people with hair loss. Zinc supplements can reduce hair loss by bringing low nutrient levels back 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. A study of women suffering from hair loss found that 50 mg of zinc per day improved hair thickness.
Another study of women with normal zinc levels and polycystic ovarian syndrome (PCOS) observed less hair loss in women who consumed a 50 mg zinc supplement daily for eight weeks than those who were taking a placebo (an ineffective substance given to 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 without low levels or underlying health conditions associated with zinc status. zinc.
The average daily amount of zinc needed to meet the nutritional needs of 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 most zinc include:
- Oysters: 32 mg per 3 ounces
- Beef: 3.8 mg per 3 ounces
- Breakfast cereals and oatmeal: 2.3 mg per cup
- Pumpkin seeds: 2.2 mg per ounce
You only absorb between 5 and 50% of the zinc found in food. This quantity may vary depending on the food source of zinc and the composition of the meal.
Plant foods contain less zinc than their animal counterparts. In addition, certain substances present in plants (phytates) influence the absorption of zinc. So, absorbing zinc on a plant-based diet may be more difficult.
Zinc deficiency is less common in the United States because most people meet their needs through food or supplements. Insufficient levels of zinc are more common in low- and middle-income countries.
It’s possible that a zinc supplement will do more harm than good, especially if you take too much. Always consult a healthcare professional before starting a new supplement.
In the United States, the Food and Drug Administration (FDA) does not regulate supplements in the same way that it regulates prescription drugs. This means that some supplements may not contain what is stated on the label. When choosing a supplement, look for third-party tested products and consult a healthcare professional, registered dietitian nutritionist (RD or RDN), or pharmacist.
Avoid zinc if you are allergic to it or its components (parts). Seek 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) should consult a healthcare professional before starting to take zinc supplements.
- The Food and Nutrition Board (FNB) of the Institute of Medicine (IOM) has set the upper limit of tolerable consumption for zinc 40 mg per day for every adult, including those who are pregnant or breastfeeding
The tolerable upper limit (UL) reflects the maximum daily amount a person can take without risk of adverse health effects in most individuals.
FNB does not recommend taking doses of 50 mg of zinc or more for a prolonged period. Excess zinc can affect copper absorption and reduce immune function.
Too much zinc can cause unwanted effects. Although it is difficult to exceed recommendations through diet alone, toxicity is possible with zinc supplements.
Side effects include:
Long-term side effects, such as reduced immune function, are also possible.
Excessive zinc supplementation can also impact the absorption of other vital micronutrients like copper and iron.
Zinc can interact with certain medications and these can affect zinc levels. These medications include the following:
- 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 in which copper levels in the body are too high. Zinc supplements may reduce the absorption and effect of penicillamine. Taking zinc and penicillamine at least an hour apart may reduce this interaction.
- Diuretics: Diuretics prevent buildup and help remove excess fluid from the body. Specific types of diuretics may increase the elimination of zinc through urine, helping to reduce nutrient levels.
It is essential to carefully read a supplement’s ingredient list and Nutrition Facts table to know which ingredients and how much of each ingredient are included. Review the supplement label with your healthcare professional to discuss potential interactions with foods, other supplements, and medications.
Other nutrients contribute to healthy hair. However, limited research supports taking these hair growth supplements only if you are not deficient in these nutrients.
Hair is mainly made up of protein. Not eating enough protein can contribute to hair loss.
It is not known 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 establish 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 people may need more protein.
Foods rich in protein include:
- Animal meat
Hair loss is associated with iron levels. Hair cells are among the most active in the body and require adequate iron levels to function properly. However, there isn’t much evidence showing the benefits of iron supplements for hair growth without low iron levels.
The FNB of the IOM of the National Academies recommends the following daily iron intake for adults:
- 8 mg for men
- 18 mg for women aged 19 to 50
- 8 mg for women over 51
- 27 mg for pregnant people
- 9 mg for breastfeeding people
Dietary sources of iron include lean meat, seafood, and fortified grains and cereals.
Omega-3 fatty acids
A deficiency of omega-3 fatty acids is associated with hair and eyebrow loss. A randomized controlled trial of women with hair loss found that 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, of which fish oil is low, and the added antioxidants may have contributed to the beneficial results.
There is no recommended dietary level for omega-3 fatty acids. However, adults are recommended to consume the following amounts of omega-3 fatty acids daily to ensure adequate nutrition:
- 1.6 g for males
- 1.1 g for females
- 1.4 g for pregnant people
- 1.3 g for breastfeeding people
Foods rich in omega-3 fatty acids include:
If you’re concerned about hair loss, talk to a healthcare professional to help identify the underlying cause.
A healthy diet with enough nutrients and protein provides the best support for hair growth. Sometimes a nutrient deficiency can contribute to hair loss. If you have low levels of zinc or iron, taking a supplement can help restore nutrient levels and promote hair growth. But if your levels of these minerals are already within the normal range, a supplement likely won’t promote 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 affecting the absorption of other minerals essential to health.
Frequently asked questions
Do hair growth supplements work?
It depends. Supplements that correct a nutrient deficiency can reduce hair loss. However, the data does not support supplements intended for hair growth in individuals who already receive enough of these nutrients.
What is the best supplement for hair growth?
There is no better supplement for hair growth. Instead, overall nutrition from a balanced diet is fundamental for hair growth. Contact your healthcare professional to find out if hair loss may be the result of an underlying problem or nutrient deficiency.
What is the best biotin supplement for hair regrowth?
Despite its mainstream popularity, there is little evidence supporting the use of biotin for hair regrowth. In healthy individuals, biotin does not promote hair growth. However, biotin supplements may promote hair growth in people with low biotin levels.