The real story about carbs and breast cancer

Many women tired of low-carb diets may fearfully keep on counting carbs because of a recently published study that links eating a lot of carbohydrates with an increased risk of breast cancer. But fears about carbs based on this study stem from a misinterpretation of what it really says. The details must be examined.

The study compares the eating habits of women diagnosed with breast cancer to women who were cancer-free in Mexico. The women ranged in age from 20 to 75 years old. Women with the highest proportion of their calories coming from carbohydrates were more than twice as likely to have breast cancer as those with the lowest carbohydrate consumption.

But wait: Everyone in this area of Mexico eats a high-carb diet. While Americans on a low-carb diet might get 10 to 20 percent of their calories from carbohydrates, a "low-carbohydrate" diet for the women of this region means 52 percent of their calories or less. This study really compares women on moderate-carb diets to women on very high-carb diets.

A partial picture
Furthermore, focusing on the total amount of carbohydrates that these women eat is still only a partial picture of their diet. Foods with carbohydrates can be vegetables, fruits, dried beans, high-fiber whole grains, low-fiber refined grains, sweets, bakery goods, or soft drinks. It is possible to eat diets equal in the amount of total carbohydrates with completely different nutritional profiles.

The main sources of carbohydrates for the women in this study were tortillas, soda and white bread. When the researchers looked at specific kinds of carbohydrates and breast cancer risk, eating more total starch (including refined grains) was unrelated to breast cancer risk. Higher sugar consumption, however, was linked with increased breast cancer risk.

Test yourself Breast cancer: What's your risk?

Although this study links higher sugar consumption with breast cancer risk, it cannot tell us if eating more sugar will increase breast cancer risk. Some other aspect of a high-sugar diet might really be the problem. For example, those who eat more sweets may eat less vegetables and fruits, thus obtaining fewer of the cancer-fighting substances that are in produce. A higher intake of calories could also be the problem. Diets high in sugar easily increase the number of calories a person eats. And in this study, a higher total calorie consumption was linked with increased breast cancer risk.

Women with breast cancer in this study also ate less insoluble fiber than those who were cancer-free. Insoluble fiber is found in whole grains, vegetables, beans, nuts and some fruits. Although fiber may or may not protect against breast cancer, a lower insoluble fiber intake is a sign that a person eats fewer whole grains and vegetables. In addition to fiber, these plant foods contain a variety of substances, like vitamins, minerals, lignans and other phytochemicals that experts suspect are highly protective.

Should women continue or fearfully start counting carbs in response to this study? No. We should always base our health choices on conclusions from a comprehensive body of research, not the results of one study.

This study should remind us of the sense in following guidelines to lower cancer risk from experts like the American Institute for Cancer Research. AICR's guidelines are based on thousands of studies. These guidelines stress the multiple benefits of a diet high in vegetables, fruits, whole grains and beans. All carbs are not the same in value for your health.

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