Eating too much red meat could increase breast cancer risk

Posted by Heather Gehlert at 1:05 PM on March 28, 2007.

If animal cruelty, environmental degradation and a growing Type II diabetes epidemic aren't enough reasons to be cautious about eating red meat, here's another: A study published in the November 2006 issue of the Archives of Internal Medicine has found a correlation between red meat consumption and hormone-fueled breast cancer.

The results, part of the Nurses Health Study II conducted by Harvard University researchers, were based on an analysis of 90,000 premenopausal women between ages 26 and 46. Researchers followed the women for 12 years, tracking their red meat intake, and found that as red meat consumption increased, so did the risk of breast cancers fueled by the hormones estrogen and progesterone.

According to an article published in Kansas City infoZine, "After adjusting for established risk factors, including weight, alcohol, and consumption of fruit, vegetables and dairy foods, the researchers found that women who reported eating more than one and a half servings of red meat per day had almost twice the risk of developing hormone receptorpositive cancer compared with women who reported eating three servings or less of red meat per week."

The study researchers note that the use of hormones in cattle production could be at least partly responsible for the link between meat-eating and hormone-driven breast cancers. About two-thirds of cattle raised in the U.S. today are injected with growth hormones.

The correlation between red meat and breast cancer might also to do with the way the meat is cooked.

"Studies suggest one reason for the increased cancer risk relates to the heterocyclic amines (HCAs) that form when red meat is cooked at high temperatures (like frying and grilling), especially well-done," writes Karen Collins in the infoZine article. "In laboratory studies, HCAs bond to estrogen receptors and create estrogen-like effects. In earlier research with women past menopause, those who consistently ate hamburger, beef steak and bacon very well done -- thus getting high levels of HCAs -- had more than four times the breast cancer risk of women who consumed these meats rare or medium done. ...

"Although red and white meat both form HCAs when cooked at high temperatures, red meat is higher in a particular kind of easily absorbed iron, called heme iron. Laboratory studies suggest that heme iron may increase colon cancer risk by damaging the colon lining and increasing the growth of precancerous cells. Several population studies link higher heme consumption with greater colon cancer risk. Scientists say that heme iron may interact with estrogen in enhancing initial development of breast tumors."

The meat's fat content could be another culprit: "Several studies link higher fat intake with higher levels of estrogen and a substance the body can convert to estrogen," Collins writes. "Higher saturated fat consumption seems to raise levels of insulin, a hormone that may promote development of breast cancer regardless of estrogen sensitivity.

More research needs to be done to determine which risk factors -- meat type, cooking method, fat content, bovine growth hormones -- relate most closely to breast cancer. Although this study leaves some questions unanswered, for now, it's probably a smart idea for women to limit how much red meat is in their diet. A little prevention can go a long way.

Tagged as: breast cancer, red meat

Heather Gehlert is a managing editor at AlterNet.