There are some major factors that influence your hair. Yes, of course, your genes play a big role. So does your age. And the hormones in your blood, as well as the nutrient balance or deficiencies you may be carrying.
Lifestyle also makes a difference in how our hair fares. For example, if you are stressed, or unable to get enough sleep and rest, then even the best food (nutrients) and treatments (scalp and hair tonics and lotions) cannot help the failing health of your hair, nails, and skin.

When it comes to the diet factor, it has been scientifically proven that nutritionally enriched foods help your hair—and can influence your hair’s thickness, its growth or shedding, how shiny it is, and even its likelihood of greying.
There are multiple nutrients that encourage hair growth: such as Biotin (a B vitamin), Vitamin D, Vitamin E, Iron, Vitamin C, Omega-3 fatty acids, etc. Sources of foods that contain these essential proteins given below are from all three, nonvegetarian, vegetarian, and vegan. Take a pick as per your own protocol.

The 3 most important Vitamins for hair growth:
1. Protein: Hour hair is made of the protein keratin. Keratin, like all proteins, is made up of a unique blend of amino acids. Eating enough protein is not just for athletes or would-be Schwarzenegger types. It is necessary for a healthy immune system and required for organs like your heart, brain, and skin to function properly. The nutrient is also touted for its ability to help control appetite and enhance muscle growth. One egg, one half-cup of chickpeas, or a small handful of nuts all provide roughly 6 grams of protein. A piece of chicken or fish the size of a deck of cards offers about 30 grams. To get your fill of protein and amino acids, you must eat food items like poultry, lean meat, and fish, chickpeas, lentils, oats, and beans. If your doctor says so, you can also supplement various protein support products, such as collagen supplements.

2. B vitamins: B vitamins, like biotin and niacin, can help support hair growth by supporting cellular energy production and tending to free radicals and encouraging healthy hair growth. Biotin supplements are often glamorised as a treatment for hair loss and to promote healthy hair, skin, and nails. It warns that although a deficiency of biotin can certainly lead to hair loss and skin or nail problems, evidence showing the benefit of supplementation is inconclusive. Alcoholism can increase the risk of biotin deficiency and many other nutrients as alcohol can block their absorption. Many pregnant women show a mild biotin deficiency despite eating adequate intakes, though the exact reason is not clear. What are the fallouts of biotin deficiency? You suffer thinning of hair, scaly skin rashes around eyes, nose, mouth, brittle nails, etc. Harvard Health gives an interesting insight on why raw egg consumption may hamper one’s biotin absorption. Those who use raw eggs in recipes for mayonnaise, Caesar dressing, or eggnog may want to reconsider– beware! A protein in raw eggs called avidin can bind to biotin, preventing its absorption. Cooked eggs are safe as the avidin is broken down when heated. Food sources for Biotin: Meat (especially organ meat), fish, eggs, seeds, nuts, and certain vegetables (sweet potatoes, broccoli, and spinach), as well as supplementation.

3. Vitamin D: Yes, even the sunshine supplement is linked to healthy hair. Vitamin D is thought to be one of the fat-soluble vitamins needed for creating and supporting functioning hair follicles, says mindbodygreen.com. Harvard Health says vitamin D is not technically a vitamin as it breaks the other rules for vitamins: it’s produced in the human body, it’s absent from all the natural foods except fish and egg yolks, and even when it’s obtained from foods, it must be transformed by the body before it can do any good. Vitamin D is not one chemical but many. The sun’s energy turns a chemical in your skin into vitamin D3, which is carried to your liver and then your kidneys to transform it to active vitamin D. Food sources to acquire vitamin D are shiitake mushroom (edible mushrooms native to East Asia) and button mushrooms, mackerel, sockeye salmon, cod liver oil, sardines, and eggs.