The Republican-American The case for a raw-food diet

Thursday, June 26, 2008 10:06 AM EDT

The case for a raw-food diet

By Kim Pierce The Dallas Morning News
A raw-food diet — basically raw fruits, vegetables and whole grains — has plenty of advocates, but whether it's the right choice for a cancer patient is open to question.

In a matter of seconds, you can find numerous testimonials online about its health benefits. However, finding peer-reviewed scientific studies, much less specific research on raw foods and cancer, is harder.

"There are only a couple dozen studies worldwide on relationships between raw-foods diets and anything else," says Suzanne Havala Hobbs, a dietitian with a special interest in vegetarian nutrition who has tracked the raw-foods movement. She knows of no studies on raw foods and cancer.

"What you could say about a raw-foods diet and cancer risk or cancer treatment could be something that's extrapolated and kind of surmised," she says, "based upon the body of evidence related to diet and cancer in general."

Still, Hobbs, who's on the faculty in the school of public health at the University of North Carolina, is far from dismissive.

"I am fascinated by some of the claims made by raw foodists," she says. "But I'm cautious about them, as well. I am sympathetic and skeptical at the same time."

When she conducted what she calls a small, low-tech study in 2005 on raw-food attitudes, practices and beliefs, the top reason for adopting a raw-food diet was health, especially protection from disease and faster healing.

Going raw

A raw-food diet is a diet made up of raw fruits, vegetables, legumes, nuts, seeds and grains — organic, if possible — that excludes meat, dairy and fish. In addition, foods are heated to no more than 116F. Raw foodists say that food enzymes, sometimes more broadly characterized as the "life force" or energy in food, are destroyed when subjected to higher heat. They believe these enzymes improve digestion and fight disease. They also say that cooking produces harmful substances.

Nutrition experts reject the enzyme theory. As registered dietitian Karen Schroeder notes in an online article from EBSCO Publishing, humans use their body's enzymes, not enzymes from plants, to break down foods. Digestion also destroys plant enzymes.

She goes on to say that acrylamide and heterocyclic amines are possible carcinogens formed in high-heat cooking, but "neither the American Cancer Society nor the National Cancer Institute goes so far as to recommend a raw food diet to reduce the risk of cancer from these chemicals." NCI does note on its Web site that HCAs are not monitored and that there are no guidelines about limits.

A strict raw-food diet also can result in deficiencies of calcium, iron, B-12 and protein. But, at least in the case of calcium, it's unclear what effect this has on health. A small 2005 study at Washington University found that while raw-food vegetarians had lower bone mass than a control group on a typical American diet, their bone turnover was normal.

Tweaking the diet

"I think there's good evidence to say, 'Yes, some raw foods, like salads, are a good thing,"' says Lawrence Kushi, associate director for etiology and prevention research at Kaiser Permanente in Northern California. "A lot of other foods benefit from being cooked."

Kushi says that water-soluble vitamins, such as C and B, are leached out of foods when cooked. But sautéing foods in a little oil improves the body's uptake of fat-soluble nutrients such as the carotenoids found in tomatoes, greens, and orange fruits and vegetables. "Having a variety of preparations is the way to go," he says.

Even among people who support the raw-foods approach, compliance may not be 100 percent. Jeannette Wright, 44, who manages her husband's chiropractic office in Dallas, adhered to a strict raw-foods diet for three years.

"The first year, I felt better," she says. "The second year, I was stable. By the third year, my nails were brittle, my hair thinned and I didn't have strength. My feeling at the time was that I was not getting enough protein. When I added fish, my nails got better, I got stronger and my hair got thicker." Now, she says, she eats raw foods 80 percent to 90 percent of the time.