Biotin is perhaps the more well-known player, as it’s involved in keratin production3. Research even shows that not getting enough biotin4 can lead to breakage and hair shedding—however, true biotin deficiencies are quite rare. 

Still, your body cannot make its own biotin, so you must ingest it orally. Meat (especially organ meat), fish, eggs, seeds, nuts, and certain vegetables (sweet potatoes, broccoli, and spinach) are top food sources of biotin, while targeted supplements can also provide support. 

For optimal hair benefits, you might even consider a biotin supplement with complementary nutrients, like vitamin D or collagen. We already discussed the importance of the former, but collagen also contains amino acids that are necessary for keratin production and, therefore, hair growth. That’s why you can find some hair growth supplements that have both biotin and collagen—like a few noteworthy options in this list here.