Researchers have found that hair grows faster in the summer time, and that people experience faster hair growth when they eat more fruits and vegetables. Research also shows that people with Asian ancestry have hair that tends to grow faster than people with European or African ancestry. If someone's hair is growing quickly, it could be related to a number of factors, including a healthy diet.
According to Glamour Magazine, fish oil and foods like oysters with a lot of folic acid and iron in them can make someone's hair grow quickly. Eggs can also help, and in fact, many shampoos have biotin, a vitamin found in eggs, on their ingredient list. Like fish oil, nuts have lots of omega-3 fatty acids, and this can also stimulate hair growth. If a person is wondering why her hair is growing so fast, it could be because she is eating a healthy diet.
On average, human hair grows at a rate of 6 inches per year, which equates to about a half an inch per month. When researchers compared the rate of hair growth between people of different ethnic groups, they discovered that there may be some correlation between ethnicity and rate of hair growth.