Diet in Puberty Affects Hormone Levels
Could Low-Fat Eating by Teens Lower Breast Cancer Risk?
Today, most Americans are urged by the American Dietetic Association and the American Heart Association to follow a diet similar the DISC plan -- with no more than 30% of total calories coming from all fat sources and no more than 10% from saturated fats.
"While we were studying all these boys and girls to see how diet affected their cholesterol, we decided to take some extra blood for hormone assays to see if diet might also influence hormonal changes," says Victor Stevens, PhD, a psychologist also involved in the DISC study. "Then we called the girls up to get their menstrual cycle data."
All the girls in the study had blood sex hormone levels measured before, during, and after puberty. The two groups appeared to go through puberty at the same time.
The researchers found that estrogen levels during the menstrual cycles were significantly lower in the girls who had consumed a diet with a lower total fat and saturated fat content. The average progesterone level during the later part of the cycles were also significantly lower.
"This is a great finding because there have been some studies saying there is no correlation between dietary fat intake and breast cancer risk. But the problem is that all of those studies have been on adults -- we really don't know what happens at the prepubescent stage, when breast tissue is developing," says Wahida Karmally, PhD, a Columbia University nutritionist and spokeswoman for the American Dietetic Association. "Cancer doesn't happen overnight, it takes years or decades to develop. The age when girls go into puberty might be a very important time to watch fat and monitor diet in order to reduce this risk."
So what can parents do for their young daughters?
"The keys to getting your kids to eat more healthfully is to control what food is in the house and to show by example," says psychologist Stevens. "Of course, we started working with these kids when they were 8 to 10, and that age, parents have a lot of control over what kids eat. But even with teenagers, controlling the food that is in the house is the top strategy for getting kids to eat more healthfully. If you have junk food in the house, they will eat it. If there is fruit, they will eat that. But if you show them you are eating healthy, they will most likely eat that way, too."