Update On Nutritional Protection


Our annual review of the hottest new research on diet and disease

Mussels in a tasty garlic sauce. Whole-wheat fettuccine, topped with sweet red and yellow peppers. Tangy fruit salad made with bananas, oranges, grapefruit and yogurt. Succulent dishes for sure--but much more. These and other foods, or their components, have been linked to lower risk of certain illnesses, including heart disease and cancer. In some cases, the scientific evidence has been pouring in for years. But recent research has added some new twists to the diet/disease connection.

Here are some of the highlights from this more recent work. We think they're just about the most intriguing and promising nutrition against-disease news of the year.

Think of it as color wars. On the winning team: green, yellow and orange vegetables and fruits. On the losing side: a host of cancers.

We've been hearing more than ever in recent months about the potential of carotenes (substances in fruits and vegetables that the body converts to vitamin A) to prevent and even treat cancer. Last year, for instance, researchers at the School of Public Health of the University of Minnesota and other research institutions published a study of nearly 500 men that showed that those who ate more beta-carotene-rich foods were less likely to die of cancer (even if they were smokers).

And it's not just lungs that benefit. Researchers at the University of Utah School of Medicine compared dietary information from 85 women with ovarian tumors with that of 492 healthy women. They found that women who ate the most beta-carotene-rich foods had half the ovarian-cancer risk of those women who consumed the smallest amounts (American Journal of Epidemiology, vol. 130, no. 3).

There's more. Researchers from the University of California--Irvine Clinical Cancer Center and the University of Arizona Cancer Center looked at the effect of beta-carotene on oral leukoplakias (precancerous sores inside the mouths). Seventeen people with oral leukoplakias were given 30 milligrams of supplemental beta-carotene per day for three months. At the end of the studies, two patients had complete remission, 12 had partial remission, one showed no change and two got worse. That's an 82 percent positive response rate.

The ultimate goal of researchers: an effective natural cancer treatment with no pain and minimal expense. They say that until they can confirm such preliminary results, the best bet is for people to eat generous daily portions of carotene-rich fruits and vegetables. Some good choices are carrots, sweet potatoes, cantaloupes, pumpkins, sweet red peppers, butternut or acorn squash and dark green leafy vegetables. Iceberg lettuce won't help; neither will red beets. (But tomatoes will.)

For years now, heart-conscious eaters have suffered a sinking feeling when offered crabs, clams, oysters and mussels. "Too much cholesterol!" they moaned. Now a new study suggests that these seafoods may actually effect positive changes in blood cholesterol. Researchers at the University of Washington in Seattle fed 18 men one of these seafoods, or squid or shrimp, in place of meat, eggs and cheese. For the men who ate the crabs, clams, mussels and oysters, levels of two kinds of harmful cholesterol, VLDL and LDL, dropped. Levels of the good cholesterol (HDL) rose.

Alas, shrimp and squid sank to the bottom of the ratings. Men who ate these had no changes in their blood lipids (American Journal of Clinical Nutrition, June 1990).

So, the researchers conclude, moderate consumption of the winning types of seafood--especially in place of fatty fare--may be a good move for the heart. One caveat, though: Preparing these goodies with extra fat, such as butter, offers no advantage at all.

Scientists from many countries recently combined and reanalyzed information on diet and breast cancer from 12 separate studies, involving 10,000 women worldwide. One consistent finding: There was a significant relationship between higher intake of saturated fat and higher breast-cancer risk for postmenopausal women. The research also revealed a link between higher dietary vitamin C intake and lower breast-cancer risk for all women (Journal of the National Cancer Institute, April 4, 1990). The researchers projected that if all women in the United States were to reduce the amount of saturated fat in their diets--to 9 percent of total calories from saturated fat (down from current levels of 13 to 15 percent) --and increased fruit and vegetable consumption to reach a vitamin C intake of around 380 mg. per day, the lives of 9,000 women would be saved every year. This is easy enough to accomplish, since one 8-ounce glass of orange juice has 124 mg. of vitamin C; one raw sweet pepper has 95 mg.; one cup of raw broccoli has 82 mg., and one cup of raw cantaloupe has 68 mg.

How to get enough fiber? Let us count the ways. New research points to a lot of possible good sources--and plenty of benefits of high-fiber eating.

A new study, for example, from the Louisiana State University, found rice bran nearly as effective as oat bran in reducing blood-cholesterol levels in 11 people. (Rice bran is the stuff they take off brown rice to make it into white rice.)

Another possibility: barley. Montana State University researchers assigned 22 people with high cholesterol levels to either a diet rich in oats or one rich in barley-flour products. After six weeks, cholesterol levels dropped an average 12 points in both groups.

Then there's the fiber/cancer connection. It was highlighted recently by the very first study suggesting that an ordinary food may help inhibit a premalignant condition. New York Hospital/Cornell Medical Center scientists in New York studied 58 people with precancerous polyps in the lower intestine. The polyps put them at risk for colon and rectal cancers. Over four years, half the participants ate a cereal high in wheat bran. The others were given a low-fiber look-alike. In the people who followed the high-fiber diet, polyps were more likely to shrink in size and number than to grow. The low-fiber group enjoyed no such benefit.

This was just one recent example of several studies suggesting that high fiber intake may deter cancer. Last April, a National Cancer Institute study of 10,000 people offered more confirming evidence. It showed that people who ate generous amounts of many different fiber-rich foods, like vegetables, fruits and grains, enjoyed a significant reduction of colon-cancer risk--up to 40 percent.

"Based on these results, people shouldn't focus on eating just one type of fiber," says Bruce Trock, Ph.D., an epidemiologist at the Fox Chase Cancer Center in Philadelphia. "They should take advantage of the wide range of sources." The National Cancer Institute guidelines recommend 20 to 30 grams of fiber per day. How to hit the target? Eat a serving of a high-fiber cereal, three servings of whole-grain bread, four servings of fresh vegetables and two servings of high-fiber fresh fruit each day.

We know that sodium can contribute to high blood pressure in sodium-sensitive people. Now scientists are investigating the possibility that, regardless of sodium's effect on blood pressure, it might cause arterial damage, cholesterol buildup and, eventually, strokes and heart attacks. These are the implications of recent animal research by Louis Tobian, M.D., a professor of medicine at the University of Minnesota School of Medicine. In one animal study, published in the journal Hypertension last June, Dr. Tobian reported that high-salt diets increased damage to the animals' arteries and increased mortality even when the salty diet didn't raise the animals' blood pressure.

But Dr. Tobian also published encouraging news about the possibility of potassium counteracting sodium's effect. In the American Journal of Hypertension (February 1990), he reported that in rats, high-potassium diets reduce cholesterol deposits in the arteries and lower blood cholesterol levels--compared to levels in rats fed normal amounts of potassium.

In a follow-up study published in the same journal in June, Dr. Tobian compared a group of rats that were fed a diet high in salt with rats given a high-salt/high-potassium diet. Those getting extra potassium had less hypertension, a lower incidence of strokes, less severe damage to arteries in the brain and kidney, and lowered mortality.

If this research is confirmed in humans, it will mean that many people--even those whose blood pressure doesn't rise from consuming sodium salt--could protect against strokes and heart attacks by minimizing sodium intake and eating plenty of potassium-rich foods like bananas. Other potassium-rich foods: apricots, avocados, potatoes, lima beans, spinach, yogurt, dates, orange and grapefruit juice, chicken, brussels sprouts, skim milk, carrots, tomatoes and prunes.

Several months ago, we told about a soon-to-be-published study suggesting that a program of low-fat eating combined with other lifestyle changes could actually reverse the progress of heart disease in some people. The study was finally published in Lancet in July and was welcomed by other scientists whose work also suggested that artery damage could be undone.

In the Lancet study, Prevention advisor Dean Ornish, M.D., an assistant clinical professor of medicine at the University of California, San Francisco, put 28 heart patients on a vegetarian diet with fewer than 10 percent of calories from fat. Every day, this experimental group of patients also did moderate exercise (usually walking), plus yoga and meditation.

Meanwhile, a control group of 20 patients followed the standard American Heart Association lifestyle prescription: They reduced fat to under 30 percent of calories and engaged in moderate exercise. Results: After just one year, arteries had begun clearing in 82 percent of the experimental-group patients--even those with severe coronary blockages. In contrast, in the control group the blockages of most patients (53 percent) worsened.

Experts say that the 10 percent-fat diet is not for everyone and that the AHA's 30 percent is still a good bet for most people who want to help prevent heart disease in the first place. But the study, along with other heart-disease research, suggests that diet may play a heroic role in the healing process that experts once said was impossible.


by Cathy Perlmutter

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