Dec. 19, 2002 -- The scourge of teenaged life -- acne -- may result from the very diet that feeds it, suggests a new study that flies in the face of three decades worth of conventional thinking on the cause of facial blemishes.
Editor's Note: Food Pyramid Replaced
In June 2011, the USDA replaced the food pyramid with a new plate icon.
And this time, it's not just isolated items such as chocolate or pizza being implicated. It's the entire typical western diet, a gamut of highly refined starchy and sugary foods that not only includes those "junk" foods but also the very breads, cereals, and carbohydrates that are the cornerstone of the USDA Food Pyramid.
The theory, reported in the December issue of Archives of Dermatology: Most staples in the American diet are high-glycemic foods -- those that tend to spike blood sugar levels and have already been implicated in increasing risk of diabetes, obesity, cholesterol, and other health conditions.
But they also cause acne, says Loren Cordain, PhD, a Colorado State University health and exercise scientist and lead researcher of the study. He says these foods cause acne by triggering a "hormonal cascade": By raising levels of insulin and insulin-like growth factor (IGF-1), more male hormone testosterone is produced, which leads to overproduction of more sebum -- the greasy gunk that blocks pores and triggers acne. Researchers have long known that elevated testosterone levels does trigger acne.
"If you eat grains, drink milk, or have any processed foods, you essentially have a high-glycemic load diet," Cordain tells WebMD. "About 85% of the grains in the western diet are refined and highly glycemic. Half of the total per capita calorie intake in this country is high glycemic load foods. It's a universal manifestation of western foods."
But why are teens most likely to wear the battle scars of a national diet consumed by those of all ages? "Because the teenaged years are a time of natural insulin resistance," Cordain explains. "The teens are growth years; for tissues to grow, they become insulin resistant."
In the U.S., acne plagues up to 95% of teens and about half of adults under age 40. Yet some primitive populations eating all-natural foods are virtually pimple-free, says Cordain. His international team of researchers studied 1,200 people (including 300 teens) in New Guinea and 115 (with 15 teens) in remote Paraguay and couldn't detect a single zit in two years of study. These people only eat what they hunt, gather, or grow themselves -- fruit, vegetables, seafood, and lean meats -- and no refined foods.
"We then looked at other studies that examined incidents of acne in similar populations -- South Americans and New Guineans now living in westernized settings," he tells WebMD. "We found that when they become more westernized and start eating like Americans, they do develop acne," he notes. "So it's not genetics."