Biotin
Biotin is one of the most important nutrients for hair health and growth. This water-soluble vitamin is part of the vitamin B family and helps convert nutrients into energy. Without enough biotin, you can experience hair loss, dry scalp and skin, brittle nails, and even depression. But here's the thing to keep in mind before you run out and down a bottle of biotin: you shouldn't take too much of any supplement and trying to treat thinning hair with biotin only works if you have a biotin deficiency. Incorporating biotin into your supplement regimen when you're already getting enough biotin through your diet will not make your hair grow faster or longer.
Zinc
Zinc is a tricky supplement to master and one that, more than any other on this list, requires a doctor’s consultation and supervision. Too little zinc can cause hair loss — but too much zinc can also cause hair loss because it disrupts the absorption of key minerals like magnesium and iron (which is also important for hair growth). But just enough zinc can keep your hair follicles strong and healthy.
Fish Oil
You already know how beneficial omega-3 fatty acids are for your body and health. But a few studies have found that the nutrient you can get from fish oil is also nourishing to the scalp and can help with hair regrowth.
In a 2015 study published in the Journal of Cosmetic Dermatology, 80 healthy women with mild female pattern hair loss with given fish oil, blackcurrant seed oil, vitamin C, vitamin E, and lycopene supplements every day for six months. Hair density increased by 62 percent of the women and 90 percent experienced a decrease in overall hair loss.
A Multi-Vitamin
A quality multi-vitamin provides a well-rounded balance of key nutrients you may not be getting enough of in your diet — including zinc, protein, and iron, all of which are needed for hair growth and health. If you think your diet isn't providing sufficient nutrients, start here: with a great daily multivitamin that doesn't contain fillers or artificial dyes or ingredients.
Vitamin D
Like biotin, a lack of vitamin D is associated with health problems that include hair loss, fatigue, and depression. The problem, particularly if you are a vegetarian or vegan, is that many foods with vitamin D are derived from animal sources (including eggs, cheese, milk, and tuna). If you sense you may be lacking this vitamin in your diet, ask your doctor for blood work so that you can determine where you are deficient before relying on this supplement.
Vitamin C
Ongoing research has found that free radical exposure can be a potential cause of hair loss, which is why hair care experts recommend taking a daily vitamin C supplement to counteract hair fall. This powerful antioxidant helps protect against the oxidative stress caused by free radicals and even plays a significant role in rebuilding collagen, a vital protein that makes up the structure of hair follicles. Vitamin C also helps your body absorb iron, a mineral necessary for hair growth, too!