The recent results from the Women’s Intervention Nutrition Study renew hope for breast cancer survivors. The women who followed a low-fat diet in this study reduced their risk of a recurrence during the next five years by 24 percent. Although it is important to know how much less fat these women ate and how they cut back, less fat may be only a part of the reason for their lower cancer risk.
This important study tracked two groups of women aged 48 to 79 for five years who had received treatment for early breast cancers. One group received nutrition counseling to learn how to reduce their fat consumption, while the other group was merely told about healthful eating without fat reduction. The first group decreased the fat in their diets from about 29 percent of calories to about 20 percent, eating an average of close to 33 grams of fat a day. The second group averaged about 51 grams daily.
An examination showed that some women in the first group who consistently met the fat targets set for this group chose lower-fat types of cheese, red meat, poultry, added fat (like salad dressing) and sweets. The biggest reason that these women succeeded better at meeting the fat goals, however, is that they cut back more on high-fat foods, such as muffins, doughnuts, cookies, snack foods, dairy desserts, cheese, nuts, eggs, red meat and added fats.
The skinny on fat
Despite the convincing results of WINS, the impact of dietary fat on breast cancer risk and recurrence remains unclear. Different types of fat or various proportions of fats may have different effects. For example, omega-3 fats, found in certain fish, walnuts and flaxseed, may protect against breast cancer. The risk from fat may also vary with a woman’s life stage. Other diet and lifestyle choices could also override fat’s influence.
One major factor that could help explain the lower cancer risk of the low-fat WINS group is a higher consumption of vegetables and fruits. A Swedish study found that people who had a low-fat diet ate more vegetables, fruits and cereals. These foods have plenty of cancer-protective nutrients and fiber.
Low-fat diets may also cause weight loss, lowering cancer risk. Studies repeatedly link both overweight and weight gain with a greater risk of postmenopausal breast cancer and breast cancer recurrence. In the Nurses’ Health Study, large weight gains after a diagnosis of breast cancer correlated with a 64 percent greater risk of recurrence; smaller weight gains led to smaller increases in risk.
While we wait to learn more about why low-fat diets reduced cancer recurrence, a smart strategy to prevent breast cancer or its recurrence should include several steps:
- First, reach and maintain a healthy weight.
- Second, limit high-fat foods because of their high-calorie content, whether or not their fat poses a direct cancer risk. Keep in mind that omega-3 fats may be protective.
- Third, although exercise was not part of the WINS study, it helps control weight. It also seems to protect against breast cancer.
- Fourth, focus on eating low-fat foods that provide cancer-fighting nutrients and phytochemicals – vegetables, fruits, whole grains and beans – rather than low-fat or low-calorie foods that offer no nutritional benefits.
- Fifth, because a low-fat, plant-based diet won’t lead to weight control if portions are too large, take portions appropriate for your energy needs.
A good guide to follow is in the American Institute for Cancer Research’s New American Plate brochures, which you can read online at www.aicr.org