The key vitamins that help make your hair grow include:

• Biotin (Vitamin B7) : Critical for keratin production, which forms hair. It strengthens hair and helps prevent thinning and breakage.
• Vitamin D : Activates hair follicles and promotes new hair growth. Deficiency is linked to hair loss.
• Vitamin A : Supports sebum production that moisturizes the scalp and promotes healthy hair. It also helps hair cells grow.
• Vitamin C : An antioxidant that protects hair follicles, helps collagen production for hair strength, and improves iron absorption, essential for hair health.
• Vitamin E : Another antioxidant that improves scalp blood circulation and protects hair from oxidative damage, aiding growth and preventing brittleness.

Additional important nutrients related to hair growth include iron and various B vitamins (such as B9/folate and B12) that support blood circulation and cell production for a healthy scalp. These vitamins are often found in foods like eggs, leafy greens, citrus fruits, nuts, seeds, fatty fish, and fortified products, and are also available as supplements for those with deficiencies or increased needs. Excess intake of some vitamins like vitamin A can be harmful, so it’s best to follow recommended doses. In summary, vitamins that make your hair grow mainly include biotin, vitamin D, vitamin A, vitamin C, and vitamin E, along with supporting minerals like iron and certain B vitamins. They promote hair follicle activation, hair cell growth, scalp health, and protect hair from damage. If you want, I can also provide natural sources and recommended daily intakes for each vitamin. Let me know! This information is based on multiple reliable sources on hair-friendly vitamins and supplements.