A dozen women sat in a circle in a UCLA classroom one recent evening, hashing out the intricacies of fats--those insidious passengers in five-cheese risotto and creme brulee that may well be lurking behind the rising rates of certain cancers.
They were educated, accomplished women. They wore bifocals and blazers, badges of professional middle-age. But as the evening wore on, the conversation turned confessional: They talked about dessert the way recovering alcoholics talk about a drink.
Could you eat pumpkin pie without the crust? Could you use mozzarella in macaroni and cheese and have it not be stringy? What to do with that leftover stuffing beckoning from the freezer? Anyone know how many fat grams reside in a chicken- fajita pita?
Their monthly version of dietary group therapy is part of a nationwide research project looking into whether women can stick to a low-fat regimen. If they can, a larger study has been proposed to explore, over many years, whether a low-fat diet might cut one's risk of cancer.
The outcome of even this first study remains unclear. As the participants tell it, they lurch between abstinence and overindulgence. But if they succeed in minimizing their fat intake, Marilyn Aronson, who conducted the UCLA session, believes there is much to be gained.
"Diet is not involved in every kind of cancer," says Aronson, a clinical research nutritionist. "But I do believe that there are a lot of people suffering from cancer who might have been able to avoid it, or at least delay it, had they eaten differently."
An estimated one third of all cancer deaths may be related to the food we eat. That's as many as, perhaps more than, can be traced to tobacco. With some 485,000 cancer deaths in the United States each year, that means 160,000 people will die of cancers traceable to diet.
Yet, precisely what it is in foods that promotes cancer or protects against it remains unclear. The question is hotly debated. Most researchers agree that alcohol consumption and obesity play a central role in certain cancers. But beyond that, there is little consensus.
Dietary fats are a prime suspect. They have been linked to cancers of the colon, breast, prostate and lining of the uterus. But research on the relationship between fats and cancer is contradictory, and some experts believe the problem may be calories, not fats.
Fiber, too, has attracted much attention. Many believe it helps protect against colon cancer. Again, research findings conflict. Skeptics wonder whether to credit the fiber in high-fiber diets, or simply the diets' relative paucity of fats.
Then there are vitamins. Foods rich in Vitamin C and Vitamin E may inhibit colon tumors, research suggests, while those containing Vitamin A and its precursors may protect against cancer of the lung. But are the vitamins themselves responsible, or is it something else in those foods?
Answering these questions is surprisingly difficult. One reason is that few people can recall in detail what they have eaten. Research subjects may remember what they swallowed yesterday, or last week, but not 15 years ago when perhaps it mattered most.
What's more, some foods themselves are not well understood. Take fiber: There are more than half-a-dozen types. How much of each type is in which foods has begun to have been studied only recently. And even less is known about how each affects the body.
Finally, the process leading to cancer remains somewhat mysterious. It can take decades, involving factors that range from environment to genetics. How diet might influence that process--promoting or retarding it--has yet to be fully explained.
Nevertheless, experts say one thing is certain: Diet, like smoking, is one of the few cancer risk factors over which people have control. So experts have offered road maps for eating that may help protect against cancer, and certainly against other diseases.
Those guidelines--set forth over the past decade by the National Cancer Institute and American Cancer Society, the U.S. Surgeon General, the American Heart Assn. and the National Research Council--stress the following principles:
Avoid obesity. Drink alcohol only in moderation. Fats in the diet should account for no more than 30% of daily calories. The current American average is 40%.
Eat more foods high in fiber, such as whole-grain cereals, fruits and vegetables. The NCI recommends a daily fiber intake of 20 to 30 grams, rather than the current average of 11.
Be sure to include vitamin-rich yellow and dark-green, leafy vegetables; red, yellow and orange vegetables and fruits; citrus fruits, and juices made from any of those.
Limit salt-cured, pickled and smoked foods, which many researchers believe raise one's risk of stomach and esophageal cancers. Minimize consumption of grilled or broiled foods that have become charred, since charring can produce carcinogens.