New research has found that a woman’s menstrual cycle can affect her cholesterol levels.

National Institutes of Health researchers studied 259 healthy women between the ages of 18 and 44 over the course of two menstrual cycles. They took multiple tests to measure levels of the female sex hormone estrogen, cholesterol and triglycerides and had the participants chart their own ovulation using at-home fertility tests.

WebMD reports that they found that cholesterol levels varied by close to 20 percent over the course of the women’s cycles.

"Cholesterol levels are the highest in the first half of the cycle and then after ovulation, they start to go down," study researcher Sunni Mumford, Ph.D. told the news provider. "Cholesterol testing should be done at the same time of your cycle each month."

Added Marc Lewis, M.D., "We used to give cholesterol screens in the morning when people have fasted, and now we probably need to add another layer and that is knowing where they are in their menstrual cycle."

High cholesterol is a known risk factor for heart disease.

Eating a healthy diet and getting regular exercise are often considered key to keeping cholesterol in check. Among the herbs and nutritional supplements believed to help lower cholesterol are fish oil, flaxseed, garlic, blond psyllium, guggulipid extract, green tea extract and beta sitosterol.