The Best Supplement for Hair Growth
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 yielded mixed results. Nutrition as a whole is vital for hair growth. However, supplements of specific vitamins and minerals may be warranted in some instances to correct nutrient 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 vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.
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 supplementing with zinc can promote hair regrowth in people with hair loss. Zinc supplements may reduce hair loss by bringing low nutrient levels 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 among women with hair loss found that 50 mg daily of zinc 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 50 mg zinc supplement daily for eight weeks than those who took a placebo (an ineffective substance given to a control group). Hair loss can be a side effect of PCOS.
Ultimately, there’s not enough information to support supplementing with zinc to prevent or reverse hair loss in people without low levels or underlying health issues associated with zinc status.
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 naturally found in meat, fish, and seafood and is added to many breakfast cereals. Foods containing the most zinc include:
- Oysters: 32 mg per 3 ounces
- Beef: 3.8 mg per 3 ounces
- Breakfast cereals and oats: 2.3 mg per cup
- Pumpkin seeds: 2.2 mg per ounce
You absorb only between 5% and 50% of the zinc in food. This amount can vary depending on the food source of zinc and the meal composition.
Plant-based foods are lower in zinc than their animal counterparts. Additionally, certain substances found in plants (phytates) influence zinc absorption. So, absorbing zinc with a plant-based diet can be more challenging.
Zinc deficiency is less prevalent in the United States, as most people meet requirements through food or supplements. Insufficient zinc levels are more common in low- and middle-income countries.
It is possible for a zinc supplement to 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 tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
Avoid zinc if you’re allergic to it or its components (parts). Seek immediate medical attention if you have a severe allergic reaction (itching, hives, shortness of breath).
People with Wilson’s disease (hepatolenticular degeneration, a condition of excess copper) should consult a healthcare provider before starting zinc supplements.
- The Food and Nutrition Board (FNB) at the Institute of Medicine (IOM) set the tolerable upper intake limit for zinc at 40 mg daily for every adult, including those who are pregnant or lactating
The tolerable upper limit (UL) reflects the maximum daily amount that someone can take without risk of adverse health effects for most individuals.
The FNB does not recommend taking doses of 50 mg of zinc or more for a prolonged period. Excessive zinc can affect copper absorption and reduce immune function.
Too much zinc can cause adverse effects. While it is difficult to exceed recommendations through diet alone, toxicity is possible with zinc supplements.
Side effects include the following:
Long-term side effects like reduced immune function are also possible.
Excessive zinc supplementation can also impact the absorption of other vital micronutrients like copper and iron.
Zinc may interact with certain medications, and medications 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, impacting the absorption of both medications.
- Cuprimine (penicillamine): Penicillamine removes high levels of heavy metal 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 lower the absorption and effect of penicillamine. Taking zinc and penicillamine at least one hour apart may reduce this interaction.
- Diuretics: Diuretics prevent the accumulation of and help remove excess fluid from the body. Specific types of diuretics can increase the removal of zinc via urine, contributing to lower nutrient levels.
It is essential to carefully read a supplement’s ingredients list and nutrition facts panel to know 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.
Other nutrients contribute to healthy hair. However, limited research supports taking these supplements for hair growth only if you do not have a deficiency in these nutrients.
Hair primarily consists of protein. Not eating enough protein may contribute to hair loss.
It is unclear whether supplementing with a specific amino acid (protein molecule) can improve hair loss. Much research on amino acids includes other nutrients as well, so it’s hard 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.
Protein-rich foods include the following:
- 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’s not much evidence to support the benefits of iron supplements for hair growth without having low iron levels.
The FNB at the IOM of the National Academies recommends the following daily intake of iron in adults:
- 8 mg for males
- 18 mg for females 19 to 50 years of age
- 8 mg for females older than 51
- 27 mg for people who are pregnant
- 9 mg for people who are lactating
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 fish oil is weak in, and the added antioxidants may have contributed to the beneficial results.
There is no set recommended dietary level for omega-3 fatty acids. However, it is encouraged for adults to consume the following amounts of omega-3 fatty acids daily to ensure nutritional adequacy:
- 1.6 g for males
- 1.1 g for females
- 1.4 g for people who are pregnant
- 1.3 g for people who are lactating
Foods rich in omega-3 fatty acids include the following:
If you’re worried about hair loss, talk to a healthcare provider 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 may contribute to hair loss. If you have low levels of zinc or iron, taking a supplement may help restore nutrient levels and promote hair growth. But if your levels of these minerals are already within normal range, then a supplement likely will not support hair growth or prevent hair loss.
Taking zinc when not needed can do more harm than good, contributing to unwanted side effects and affecting the absorption of other minerals essential for health.
Frequently Asked Questions
Do any supplements for hair growth work?
It depends. Supplements correcting a nutrient deficiency may reduce hair loss. However, the data do not support supplements targeted for hair growth in individuals already getting enough of these nutrients.
What is the best supplement for hair growth?
There is no best supplement for hair growth. Instead, overall nutrition from a balanced diet is fundamental for hair growth. Contact your healthcare provider to discuss whether hair loss may result from an underlying issue or nutrient deficiency.
What is the best biotin supplement for hair regrowth?
Despite its mainstream popularity, there is limited evidence to support the use of biotin for hair regrowth. In healthy individuals, biotin does not promote hair growth. However, biotin supplements may encourage hair growth among people with low biotin levels.