Breast Cancer Study Shows No Improvement With Increased Produce Consumption
Jim Prevor’s Perishable Pundit, July 19, 2007
A new study kicked off by a $5 million grant from Wal-Mart heir John Walton, and bolstered with $30 million from the National Cancer Institute, found that diets served to a group of breast cancer survivors with eight servings of fruits and vegetables plus 16 ounces of fresh vegetable juice a day had the same recurrence rate as a group that was following standard nutrition guidelines.
Thought disappointing to advocates, it will probably relieve many women as the intervention diet was tough to stick to. To reach the eight servings of fruits and vegetables, the women were not allowed to include iceberg lettuce or white potatoes.
Juicing the 16 ounces a day was perceived as so onerous, the researchers had to allow the women to buy pre-squeezed juice.
But some say the problem may be that the study did not go far enough:
Dr. Dean Ornish, a UCSF professor and author of books advocating an extremely low-fat diet to protect against cancer and heart disease, said people shouldn’t be too quick to rule out the importance of an ultra-healthy diet.
In the study, researchers had asked women in the intervention group to cut their fat intake by 15 to 20 percent — a goal they weren’t able to accomplish. And fat intake, Ornish said, is a critical part of a healthy diet.
Ornish also noted that the diets didn’t vary all that much between the two groups of women. Both groups ate more fruits and vegetables than the average American, and neither group lost weight during the course of the trial.
“The differences are going to be minimal in the outcome because they were minimal in the intervention,” Ornish said. “What discourages me is this gives exactly the wrong message, which is ‘why bother.’ It feeds into that genetic nihilism that it’s all in my genes.”
To us it raises the question of whether the new Fruits & Veggies — More Matters slogan is really telling consumers what they need to hear:
Researchers noted that none of the breast cancer survivors lost weight on either diet. That led some experts to suggest that weight loss and exercise should be the next frontier for cancer prevention research. The study appears in Wednesday’s Journal of the American Medical Association.
“It sends us back to the drawing board,” said Susan Gapstur of Northwestern University’s Feinberg School of Medicine, who wasn’t involved in the new study but co-wrote an accompanying editorial in the journal.
“Should we really have focused on dietary components like fruits, vegetables and fat?” Gapstur asked. “Or should we be focusing, in addition to diet, on lifestyle factors including physical activity and weight?”
The dirty little secret of all produce promotion programs is that there is precious little evidence that, as an independent variable, increasing consumption of produce helps health and longevity. In fact, we use the recommendation to eat more produce as a proxy for saying “eat fewer high fat foods and reduce total caloric intake.”
In other words, we do not have much evidence that people who eat ample diets right now would improve their health by, say, continuing their current diet but then forcing themselves to eat five more produce items each night before going to bed.
In fact, the extra produce items have calories and the increase in obesity that would come from such a plan may well outweigh any benefits from phytochemicals in the produce.
It seems increasingly clear that a behavioral approach, encompassing not merely dietary recommendations but exercise and lifestyle components, are the only hope for reducing obesity.
Even with all the support of a study such as this, “the women were allowed to eat meat, but were told to get no more than 15 percent to 20 percent of their calories from fat, a goal they ultimately were unable to achieve.”
In the mega-veggies group, the women changed their eating habits substantially, mostly by increasing fruits and vegetables to as much as 11 servings a day. They failed to meet the fat target, but did eat 13 percent less in fat calories than did the comparison group.
After one year, women on the high-vegetable diet had 73 percent higher blood levels of carotenoids (pigments found in fruits and vegetables) than the other women. That indicates they were truthful about how many fruits and vegetables they ate, Pierce said.
But they may not have been so honest about the calories they ate. The super-veggie group gained 1.3 pounds and the comparison group gained 0.88 pound, on average.
“There’s no question they were underreporting on calories, especially the heavier women,” Pierce said, or they would have lost weight.
So even on this high produce diet, even with the mental burden of being breast cancer survivors and knowing that keeping thin is recommended, the women still gained weight.
If we don’t learn how to solve that problem, it is not clear that other dietary changes will matter at all.