Poor Nutrition

One whose diet is low in fruits and vegetables, and high in fast food and additives, will cause their hair to grow more slowly.
Vitamin B is essential in maintaining healthy hair, especially Vitamin B6. Hair that is not getting enough of it will be thin and fine. Examples of food that is rich in these vitamins are beans, peas, soybeans, nuts and eggs. Vitamin E is also important in hair health. Examples of foods rich in Vitamin E are avocados, nuts, seeds, and olive oil.