From omega-3 fatty acids to flavonoids, the ingredients in foods you eat every day may be potent weapons in the battle against disease.
Once-forbidden foods like chocolate, nuts, and wine made headlines in 2004 for their potentially healthy benefits, and new research suggests that the key to avoiding heart disease or cancer may be found in the cupboard rather than the medicine cabinet.
But the secret may not lie in a single wonder food. Instead, researchers say that variety may really be the spice of (long) life. To get your plate in order, WebMD asked the experts for their top picks from this year's newsmakers.
Flavonoids: What Makes Chocolate and Wine Good for You
The antioxidant-rich compounds found in the seeds and skins of plants, such as grapes, cocoa beans, and citrus fruits, first gained the attention of researchers in the early 1990s as a means of explaining the so-called French Paradox. Researchers proposed then that French people had lower rates of heart attacks because they drank moderate amounts of red wine with their meals.
Since then, more than 300 studies on grape flavonoids have shown that drinking red wine or grape juice may help blunt the artery-clogging effects of a fatty meal and reduce the risk of heart disease over the long-run.
Many of the same flavonoids in grape products are also found in varying concentrations in green and black tea as well as chocolate, but the bulk of research so far has been focused on grape flavonoids.
"It is exciting that different investigators dealing with grape products, whether it be red wine, de-alcoholized red wine, grape juice, or grape seed and skin extracts, they are all seeing some significant, potentially beneficial things," says John D. Folts, PhD, professor of medicine and nutritional science at the University of Wisconsin Medical School.
Folts says animals with high cholesterol will develop atherosclerosis or hardening of the arteries in about six to nine months, a process in humans that takes 20 to 30 years. But several recent studies have shown that when these animals are given grape products, the artery-clogging process slows down.
"The suggestion is that the same thing would work in humans," says Folts. He says the early studies on tea and chocolate flavonoids are promising, but it's still too early to draw any definitive conclusions from them.
Researchers say flavonoids may help promote heart health in several ways, such as:
- Helping to prevent blood clots, which may trigger a heart attack or stroke.
- Preventing cholesterol from entering and damaging blood vessel walls.
- Improving the health of arteries, making them expand and contract more readily, helping them carry blood more effectively.
- Stimulating the production of nitric oxide, which may stall hardening of the arteries.
Alice H. Lichtenstein, DSc, professor of nutritional science and policy at Tufts University, says although the research is reasonably good in showing that drinking a moderate amount of wine, defined as one or two glasses per day for men and no more than one glass per day for women, is associated with a lower risk of heart disease, it is also associated with an increased risk of breast cancer.
"There is still some confusion over alcohol, and I think that's understandable because it has potentially good and bad effects," says Lichtenstein. "One should not start drinking if they don't already, and they have to really weigh the risks and benefits."
She says it's difficult to make a broad recommendation for drinking wine or other types of alcohol based on its potential health benefits because there are also some people who may be more likely to have substance abuse problems with alcohol.
The "Good" Fat (Fatty Acids)
Fat also got a healthy image makeover this year thanks to new research on omega-3 fatty acids and their ability to reduce the risk of heart disease. Omega-3 fatty acids are found in fatty fish such as salmon, tuna, lake trout, and herring. In September, the FDA approved a new qualified health claim that allows foods and supplements containing omega-3 fatty acids to advertise the fact that eating the product may reduce the risk of heart disease.
Although health organizations, such as the American Heart Association, already recommend fish as a part of a heart-healthy diet based on earlier findings of epidemiological studies, Lichtenstein says new research this year offers new proof of the heart-healthy benefits of omega-3 fatty acids.
In Lichtenstein's study, women whose arteries already showed evidence of atherosclerosis who ate fish twice a week or dark fish once a week had a slower progression of their disease, as shown by X-ray images.
"Probably what happens is that when people consume more fish, they're not eating as much steak and hamburgers. So they are displacing foods high in saturated fat for one high in unsaturated fat," says Lichtenstein.
In November, the FDA also approved another new qualified health claim for olive oil based on studies that show eating about two tablespoons of olive oil a day may reduce the risk of heart disease.
Olive oil contains a type of fat known as monounsaturated fat that can lower 'bad' LDL cholesterol levels when eaten instead of saturated fats. However, olive oil contains about the same amount of total fat grams and calories as other types of fat.
New research released this year also helped explain the role of antioxidants, for better and for worse.
"Some years ago, we thought that vitamin E was protective against heart disease. Now we're not so sure about that," says Melanie Polk, RD, director of nutrition education at the American Institute for Cancer Research. "We used to think that vitamin E was valuable for a whole variety of benefits, but now we're not so sure about that either."
Several studies have cast doubt on earlier health claims about vitamin E, and a study released in November showed that taking high doses of the antioxidant may actually be hazardous to your health and shorten your life span.
"There was so much excitement over vitamin E because it seemed like such an easy answer," says Lichtenstein. "Unfortunately, it wasn't upheld with studies."
But vitamin E is just one of many antioxidants that may have potentially healthy effects, and the good news about antioxidants this year is that they may be found in unexpected places, like cereal.
Researchers have long thought that fruits and vegetables were the primary sources of antioxidants in the diet. But new research presented this year suggests that a different type of antioxidant and other phytochemicals may also be found in whole grains.
"Phytochemicals seem to be in what we call the free form in fruits and vegetables, and when we looked for these in whole grains they weren't found," says Polk. "What researchers have now discovered is that they were in different form in whole grains. They are attached to cell walls of the plant and don't get absorbed into the blood until bacteria act upon them during digestion."
"We didn't know about this bound form of phytochemicals until recently, and so the benefits of whole grains are even greater than what we thought before," says Polk.
Polk says these findings may also help explain why studies that have looked at the potential anti-cancer properties of the fiber found in whole grains have produced conflicting results.
"We know diets that are high in fiber are cancer protective, but there has been some question about whether or not it is the fiber itself," Polk tells WebMD. "It may not be fiber but maybe something else in high-fiber foods."
Confused? Mix It Up
If the conflicting research about the health benefits of different foods has you confused, researchers say the best recipe is to mix it up.
Researchers say every time they try to isolate one of the components behind the potential health benefits of a food, it doesn't seem to work.
"We have been so unsuccessful in finding that perfect food or that perfect nutrient that if you just pop a supplement you're going to have decreased risk," says Lichtenstein.
In contrast, new research suggests that it may be the ways various phytochemicals and ingredients in different foods work together that produce the biggest health benefits.
For example, a recent study showed that mice with prostate cancer fed a diet rich in both broccoli and tomatoes experienced much less tumor growth than those fed either food alone.
Another study showed that people who ate "polymeals" consisting of wine, fish, dark chocolate, fruits and vegetables, almonds, and garlic on a daily basis had a lower risk of heart disease and lived longer than those who didn't. A polymeal is a combination of foods that have been individually shown to reduce the risk of heart disease.
"When you look at individual phytochemicals, it's very exiting to see that each individual phytochemical has its own function in terms of cancer prevention and health protection. But the possibilities of looking at what they can do together working as a team could be phenomenal," says Polk. "The best way to get these substances is by eating whole foods."
Lichtenstein says researchers are now coming to the realization that certain diet and lifestyle patterns are associated with a lower risk of disease, rather than any one food.
"Fortunately those are virtually the same for heart disease, cancer, and diabetes," says Lichtenstein. "It's to consume a diet high in fruits and vegetables, whole grains, low-fat and nonfat dairy products, legumes, and fish and have regular physical activity."