Dietary supplements no substitute for proper diet

WASHINGTON (AP) -- Nutritionists call the survey alarming: More older Americans -- the people most at risk of cancer -- say they're popping unproven dietary supplements in a quest for tumor-fighting nutrients than trying to eat more cancer-protective foods.

Add this newest trend to those hot fad diets and the nation's rising obesity, and cancer experts are increasingly worried. Americans don't seem to heed the warnings that what you put on your plate day after day can truly influence whether you'll get cancer.

Eating more fruits and vegetables just must not be a sexy enough message.

"That's why the food supplements industry is worth $40 billion and why the (profit) margin on vegetables and fruits is so small they don't even get advertised," Dr. John Potter of Seattle's Fred Hutchinson Cancer Research Center says in frustration.

There's no proof yet that pills and powders prevent cancer, and some supplements may actually increase tumor risk, Potter notes.

"This is of real concern. We need people to focus more on factors we know are cancer-preventive," adds nutritionist Melanie Polk of the American Institute for Cancer Research, which conducted the recent survey of 1,010 people. More than half of respondents over age 55 took vitamins specifically to lower their cancer risk -- one quarter of them took additional supplements like garlic or fish oil -- yet just 39 percent preferred the proven method of changing their diet.

So Tuesday, the AICR launches a major campaign to teach people what a cancer-protective diet literally looks like: Fruits, vegetables, whole grains and/or beans should cover two-thirds of the dinner plate.

That's not rocket science. But who even considers cancer when they're deciding between a high-fat bacon cheeseburger or the lower-fat grilled tuna? Or measures whether that's a reasonable 1 cup of spaghetti or a whopping 3 cups? Or knows a serving of green beans is the size of half a baseball, or admits they count french fries when asked how many vegetables they eat?

Not to mention those high-protein fad diets. They do cause rapid weight loss, Potter says. But "we don't even know what the long-term consequences are," he cautions. In contrast, cancer experts recommend meat servings the size of a deck of cards.

Many factors play a role in cancer. Lung cancer, for example, is the world's leading cancer killer and tobacco is almost always the cause.

But bad diets -- continually bad, not the occasional indulgence -- are a culprit, too. People could cut their risk by one-third simply by eating more fruits and vegetables, concludes an exhaustive scientific review led by Potter.

Why? They're low in fat while high-fat diets are a risk for many cancers. They're low in calories; being overweight significantly increases cancer risk, too. Plant foods are full of vitamins, minerals and phytochemicals that help the body defend itself against malignant cells.

A single tomato, whether fresh or brewed into sauce, contains hundreds of phytochemicals such as the antioxidant lycopene, linked to reduced prostate and other cancers. Berries are high in fiber and ellagic acid, another cell-protective substance. Carrots are full of beta carotene; spinach has that antioxidant plus vitamin C and folic acid. Cherries have quercetin, another potent antioxidant. Grapes are rich in flavonoids that seem to fight heart disease as well as cancer.

Add in whole grains like wheat and oats, rich in substances that seem to impair cancerous cells' ability to invade healthy tissue.

Why can't pills substitute? Food's magic seems to be the complex interactions of dozens of phytochemicals, Polk explains.

While 190 solid studies prove the fruit-and-vegetable benefit, supplements have only a smattering of evidence, Potter says. Some ultimately may prove to be cancer-fighters -- Fred Hutchinson is about to test that in a study of 75,000 people.

But too much of one nutrient, or taking it without its companion nutrients, can be dangerous, Potter notes. Beta carotene pills have actually increased smokers' risk of lung cancer, and startling research recently concluded cancerous tumors absorb vitamin C, raising questions about megadoses.

So what do cancer experts eat? Choices at an AICR meeting last week: grilled tuna, high in "omega-3 fatty acids" that fight heart disease and show promise against certain cancers. Couscous, for high-fiber grain, with tomatoes and asparagus. Brown rice salad with dried cherries, raisins, apricots and walnuts. And for dessert, berry-filled tarts.

Copyright 2000 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Chemicals in apples slow cancer growth, scientists report
August 30, 2000
Institute of Medicine raises requirements for vitamins C and E
April 11, 2000
Broccoli beats most other veggies in health benefits
April 13, 2000

American Dietetic Association
American Cancer Society
National Cancer Institute - 5 A Day for Better Health

Note: Pages will open in a new browser window

External sites are not endorsed by CNN Interactive.