Dec 15,2006 00:00
Findings from a small published study performed by researchers at Washington University School of Medicine in St. Louis suggest that eating less protein could help protect against some cancers that have never before been linked to diet.
For years, scientific research has connected overeating with cancer. Overweight people are at higher risk of developing breast cancer, endometrial cancer, colon cancer, kidney cancer and esophageal cancer.
The research published in December in the American Journal of Clinical Nutrition indicates that lean people on a long-term, low-protein, low-calorie diet or participating in regular endurance exercise training have lower levels of plasma growth factors and certain hormones linked to cancer.
The study involved 63 people in three groups who were matched for age, sex, demographic and health factors:
The first group ate a low-protein, low-calorie, raw food vegetarian diet and was made up of 21 lean men and women.
The second group consisted of 21 lean subjects who did regular endurance running, averaging about 48 miles per week. The runners ate a standard Western diet, consuming more calories and protein than the first group.
The third group included 21 sedentary people who consumed a standard Western diet, higher in sugars, processed refined grains and animal products.
The researchers found significantly lower blood levels of plasma insulinlike growth factor 1, or IGF-1, in the low-protein diet group than in the runners group or the sedentary group.
Past research has linked premenopausal breast cancer, cancer or the prostate and certain colon cancers to high levels of IGF-1, a powerful growth factor that promotes cell proliferation. Data from animal studies also suggest that lower IGF-1 levels are associated with a long life span.
"That suggests to us that a diet lower in protein may have a greater protective effect against cancer than endurance exercise, independently of body fat mass," said study author Dr. Luigi Fontana, who is a WU assistant professor and a medical investigator for the Istituto Superiore di Sanita in Rome.
SKINNY ON LOW-FAT
Recent Cornell University studies in movie theaters, holiday receptions and homes indicate people consume an average of 28 percent more total calories when they know the treats they are eating are labeled low-fat.
"Obese people can eat up to 45 percent more," reports lead researcher Brian Wansink, in the book, "Mindless Eating: Why We Eat More Than We Think" (Bantam, $25).
"People don't realize that low-fat foods are not always low-calorie foods," says Wansink. Fat is often replaced with sugar. Low-fat snacks are an average of 11 percent lower in calories, but people wrongly believe they are around 40 percent lower.
In one Cornell study, two groups of people attending a holiday open house were given identical regular chocolates that were labeled as either "regular" or as "low-fat."
People served themselves an average of one-third more of the candies, which would have translated into 28 percent more calories if they had actually been low in fat.
A second Cornell study showed this is because people believe they will feel less guilty eating the low-fat foods, so they tend to overindulge, says study author and nutrition scientist Pierre Chandon.
The complete set of research studies were published in the November issue of the Journal of Marketing Research. It is titled "Can 'Low-Fat' Nutrition Labels Lead to Obesity?"
For policymakers and companies, the message is that new low-fat foods are unlikely to provide a solution to the growing obesity problem in the United States. People are likely to overeat low-fat foods - even if they don't like them as much as the regular versions.
© Copley News Service