Food is the Best Source of:

"When it comes to diet, the whole is greater than the sum of the parts," says David R. Jacobs, PhD , professor of epidemiology at the University of Minnesota in Minneapolis. "There may be nutrients in food that we don't even know about yet, and the effect of different nutrients working together may be better than each one working alone."

What Exactly Is Food Synergy?

Picture a pharmaceutical manufacturing plant so high-tech that it produces thousands of chemicals beneficial to human health, at a cost of only pennies per day. Now imagine that it is solar-powered, uses only water and carbon dioxide as raw materials, gives off no toxic waste, and fits in the palm of your hand.

Science fiction? No -- a simple tomato.

Or not-so-simple, considering that in addition to vitamins C and A, beta-carotene, fiber, and lycopene that protects the prostate gland from cancer, the tomato undoubtedly also contains a host of other health tonics that research is only beginning to discover.

Phytochemicals -- or beneficial chemicals made by plants -- can protect against aging, infection, cancer, and heart disease, explains Johanna Lampe, RD, PhD, of the Fred Hutchinson Cancer Research Center in Seattle. They act as antioxidants that reduce cell damage, stimulate the immune system, and fight bacteria and viruses. They can reduce blood pressure, regulate cholesterol and hormones, and prevent stroke by keeping platelets from sticking together.

"The combination of these biologic processes, rather than any one mechanism, influences disease risk," Lampe tells WebMD.

"Every vegetable and fruit has a unique profile of phytonutrients exerting beneficial effects on our bodies to prevent disease," says David Heber, MD, PhD, a professor of medicine and public health at UCLA.

So far, more than 25,000 different phytonutrients have been discovered in fruits and vegetables. Researchers are now discovering that these chemicals work in concert, orchestrating natural harmony in body systems. To keep our bodies finely tuned, the best diet is one featuring a wide variety of fruits, vegetables, whole grains, nuts, and legumes.

Variety: the Spice of Life

Of the 150,000 to 200,000 edible plants on earth, most Americans eat only three per day. For far too many junk food addicts, that boils down to French fries, ketchup, and a limp shred of iceberg lettuce on a hamburger bun.

In a Western diet, vegetables and fruits include the roots, leaves, stems, fruits, and seeds from more than 40 botanical families, Lampe says. By contrast, primitive tribes who gather plant materials for their existence eat more than 800 varieties of plant foods.

"We have a long way to go to increase the diversity and amounts of plant foods in the American diet," says Heber. "Cancer is not one disease but many, and no single food or compound can provide the different kinds of cells in the body with the unique protection they require."

Heber recommends eating up to a pound of produce each day, going beyond the five to nine servings recommended by 5-A-Day: "You need a diverse array of fruits and vegetables to get the different substances you need."

His book, What Color is Your Diet?, released June 1 by Harper Collins, groups plant foods by their colors. Filling your plate with a rainbow of hues, each reflecting a different group of phytonutrients, will help you get the variety your body craves.

Whole Grain: the Staff of Life

"Man cannot live by bread alone," the Bible says. But whole grain is surely a good start. Ironically, even though refined "white" flour became popular as a symbol of wealth, the whole wheat kernel is nutritionally far more complete.

"The nutrient-rich bran and germ layers of the kernel are loaded with antioxidants, healthful fatty acids, and other minerals and phytochemicals in addition to the fiber," says Mark A. Pereira, PhD.

"We still don't know which constituents alone or together create the good effect," says Jacobs. "But all other things being equal, men and women who eat more whole grains live longer."

Jacobs' research shows that eating whole grains is associated with lower risk of death, and with more normal values on blood tests linked to heart disease. Other studies show that eating whole grains improves blood pressure and blood sugar levels in the short-term, and reduces risk of heart disease, stroke, and diabetes.

"A good example of a whole grain meal is rolled or steel-cut oats cooked with fresh fruit and nuts," says Pereira, an instructor in nutrition at Harvard Medical School.

In Western countries, most people eat less than one serving of whole grain daily, compared with several of white flour. "Public health problems arising from inactivity and poor dietary habits will be a great challenge for decades to come," Pereira says.

Don't Pop Pills -- Eat Food

"Whole foods provide a unique mix of nutrients that cannot be mimicked by pills," says Elizabeth Pivonka, PhD, RD, president of Produce for Better Health Foundation in Newark, Del.

For example, recent research on the effect of fiber in preventing colon cancer has shown mixed results, because some studies examined fiber sources separate from foods, or ignored the potential effect of other nutrients.

"Nutritional research tends to focus on the effects of individual molecules in simple laboratory models," says Mark Messina, PhD. "The overall effect of diet on health is lost."

Testing individual supplements in the lab is much cheaper and easier to do than long-term clinical studies of diet in humans, so it gets more media hype. But dietary studies pack a bigger punch, explains Messina, associate professor of nutrition at Loma Linda University in California.

Case in point is the Dietary Alternatives to Stop Hypertension (DASH) study showing that a diet low in salt and fat, and high in fruits, vegetables, and calcium lowers blood pressure. The complexities of analyzing diets in large numbers of people over long periods of time cost $30,000 per subject, or over $10 million total.

"Yet this one study has had more impact on public policy than 100 animal studies," Messina says.

While dietary studies are more difficult, they often yield more valuable information. Calcium in the diet protects against rectal cancer, but only in combination with a low fat diet. Calcium helps prevent osteoporosis, but only if enough vitamin D is present for calcium absorption, and only if salt intake is limited, as sodium increases the body's requirements for calcium.

Messina explains that a healthy diet has many advantages over drug treatments. The statin drugs may lower cholesterol, but a diet rich in fiber, antioxidant vitamins, and soy also decreases risk of heart disease, cancer, and other diseases.

"Just eat the apple, and let the scientists worry about which nutrients in the apple are good for you," he says.

Tips for Healthful Eating

Eat up to a pound of produce daily -- or at least 5-9 servings. Choose whole grains over white flour. Fill your plate with fruits and vegetables in a rainbow of colors. Variety is key! Stock up on dried, frozen, and canned fruits and vegetables. When possible, choose fresh produce over processed or preserved foods. Keep produce visible and accessible -- a fruit basket on the table, a bowl of celery and carrot sticks in the fridge. Microwave vegetables for a quick, healthful dinner. Make fruit part of your daily breakfast and snacks. Use recipes and shopping tips from 5-A-Day at
Nanci S. Guest is a certified personal trainer & nutritionist, and is completing her Master of Science degree in nutrition this June. She owns "Power Play: Nutrition, Fitness, Performance" in Vancouver, BC, and for the past 8 years she has been providing individuals, sports teams & the community with nutritional consulting & personal training services, as well as research services, seminars and article writing for local & national publications.

Her specialization is sports nutrition, catering to a variety of athletes of all levels. Some of her elite athletic clientele include members of the Vancouver Canucks, the Vancouver Giants & the BC Lions, the Canadian National Freestyle Ski Team, Iron Man participants, athletic teams from BC high schools and universities, and a variety of other provincial and national team members.

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