The appearance of our hair is a good indicator of our internal health, its no coincidence that farmers throughout history have checked the quality of their animals coats as a guide to the animals general health. So it is far more than vanity to care about ones hair.
Leaving aside any issues about styling or colouring, healthy attractive hair grows when there is nutritional balance in the body. For general hair health its worth remembering that hair itself is 98% protein so ensuring the diet contains sufficient lean meat, eggs, nuts and fish is a good start. Selecting oily fish at least twice a week will add even greater benefit. Vitamins A, C, E and K are all part of a plan for healthy hair but the B vitamins are by far the most important. Then there are the minerals, many essential but none more so than iron.
Of course knowing all this doesnt make it any easier to achieve on a daily basis so supplementation may make things more manageable and by choosing a supplement formulated specifically to improve the hair will automatically improve nutritional balance in general.