Controversy about diet and breast cancer
May 25, 1999
Web posted at: 10:05 AM EDT (1405 GMT)
By Cathy Lu
The next time you think about grilling a steak or ordering that cheesecake, you may want to think again. These are the foods to which some scientists attribute the skyrocketing incidence of breast cancer in the United States.
One-in-eight women living in the United States will be stricken with breast cancer. But are the fatty foods that lurk in your fridge really the villains?
There is much debate about this topic, and the abounding number of studies do little to clear the air.
Pieces of the Puzzle
A 14-year study of almost 90,000 women by Harvard University and Brigham and Women's Hospital in Boston found no evidence that a lower intake of fat (23 percent of calories from fat versus 44 percent) or even particular types of fat were associated with a decreased risk of breast cancer.
A 1990 study by the National Cancer Institute of Canada found that breast-cancer rates dropped by 10 percent in postmenopausal women who decreased the amount of calories in their diet that constitute saturated fat from 14 percent to 9 percent.
Scientists at New York University compared the diets of breast-cancer patients to those of healthy women in northwestern Italy and found that the cancer group consumed more animal fat and products.
Researchers at the University of Leeds in England examined the eating habits of 1,600 women and found no link between diet and breast cancer.
Studies have suggested that in Japan the incidence of breast cancer was much lower before 1950, when diets were primarily rice-based, as opposed to in recent years, when eating habits became more Westernized.
Researchers in Sweden and at Harvard studied 61,000 women in Sweden and discovered no correlation between a low-fat diet and a lower risk of breast cancer.
Two sides, one coin
Currently, the rate of breast cancer in the United States is five times higher than in Asia. Yet there are skeptics in the medical community who want to see some cold, hard evidence before they draw any conclusions. Dr. Arthur Michel is one of them.
"Are you going to tell me that there are no other environmental factors that are any different between China and the United States other than diet?" says Michel, medical director of the Breast Center for Highland Park Hospital in Illinois. "Uncontrolled speculation is not scientific." He suggests that such factors as pesticides may be skewing the statistics.
So how do scientists who believe in the correlation between diet and breast cancer explain studies that indicate otherwise? Dr. Neal Barnard, president of the Physician's Committee for Responsible Medicine, claims that those studies merely prove that minor changes like cutting back on burgers and Ben & Jerry's don't help the fight against breast cancer.
What naysayers are willing to acknowledge right now is a tie between obesity and breast cancer, although there are other factors, such as menopause and hormone replacement therapy, that can skew an analysis. Research indicates that more body fat increases the production of estrogen, which has been known to fuel the growth of cancer cells.
"I think that being overweight probably has more hazard built into it than anything you could do dietwise," says Michel. "Women who are morbidly obese have much more breast cancer than women who are not."
A number of studies are currently underway to try to break the impasse over the diet debate.
In 2010 the Women's Health Initiative will introduce the results of a trial studying 164,000 women to determine whether a diet high in fruits, vegetables and grains will lead to fewer cases of breast cancer. There are also a number of molecular studies attempting to isolate various factors that may cause breast cancer.
In the end it's a controversy on which scientists won't easily give up. "Regardless of where you fall on the debate," says Michael Kilgore, a Clemson University researcher who is trying to isolate fats that may trigger breast cancer, "the question is far too important not to continue to study."
Copyright 1999 by WebMD, Inc. All rights reserved.
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