Does less fat mean less cancer risk?
Suggestions that a low-fat diet helps reduce the recurrence of breast cancer have reignited interest -- and some debate -- about what level of fat is best to eat.
First, a recap: The study involved 2,437 postmenopausal women, ages 48 to 79, who had been diagnosed with early-stage breast cancer. All participants received the same medical care, but half were randomly assigned to meet with a nutritionist every two weeks and remained in contact for food advice between visits. These women were counseled to eat a very low-fat diet, just 15% of daily calories from fat. Participants in the control group ate a diet with 30% of daily calories as fat.
Led by Rowan T. Chlebowski of the Los Angeles Biomedical Research Institute, the study found that about 10% of the women in the low-fat group -- compared with 12% of those on the standard diet -- developed recurrences.
That’s a small but significant reduction in risk, and it’s the first solid evidence that changes in diet can improve the outcome for women with breast cancer.
“The message is that women with breast cancer might consider following a low-fat diet in addition to getting the best medical treatment at the same time,” says Peter Greenwald, director of cancer chemoprevention at the National Cancer Institute.
The question is: How low in fat?
That’s where it gets complicated, says Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health. He wonders if the benefits shown in the study come not just from eating less fat, but also from weight loss or other changes that people made in their diets such as eating more fruit and vegetables.
While researchers determine the best course for women with breast cancer, they say there’s plenty of evidence that the following tips will help promote health no matter what your gender or health status:
* Lower the fat. Based on these new results, experts say that women with breast cancer may want to consider a diet with 20% of total calories as fat -- the lower end of what the U.S. Dietary Guidelines recently recommended. That can be challenging, since it means no butter, margarine, salad dressing with oil, cheese, egg yolks, fried food, baked goods or other foods with added oil.
For others, the guidelines say that a healthy range for fat is 20% to 35% of total daily calories.
* Eat healthy fat. Reach first for foods that naturally contain healthy fat, such as seafood, nuts, avocados and olives. Limit added fat to six teaspoons or less (for an eating plan of 2,000 calories per day) and make it healthy fat such as olive, canola or safflower oil, according to the U.S. Dietary Guidelines.
* Make smart substitutions. When you reduce fat, replace it with something healthy. “You want to eat more fruit and vegetables [and] whole grains, not fat-free brownies, cookies and ice cream,” says Alice Lichtenstein, professor of nutrition at Tufts University. Whole grains contain fiber and complex carbohydrates, which are less apt to raise blood sugar and produce surges of insulin. Some preliminary but growing evidence suggests a possible role for insulin and insulin-like growth factors in cancer development.
Remember also that fruit and vegetables are rich in cancer-preventing antioxidants and phytonutrients, as well as fiber, and are low in calories -- which helps control weight.
* Easy on the booze. Some 50 studies show that drinking alcohol “is related to a higher risk of breast cancer,” Willett notes. “Even just one drink a day roughly increases risk 10%.”
The good news is folic acid appears to help reduce risk. If you have one drink per day, which helps protect against heart disease, Willett advises taking a multivitamin to get enough folic acid. Also, eat foods rich in folic acid, including fortified cereals, breads and crackers.
* Reach a healthier weight. “Weight gain as an adult increases postmenopausal breast cancer risk,” Greenwald says. Added pounds are also linked to a poorer breast cancer prognosis. Even losing a little weight helps. Women in the low-fat group lost about four pounds.
