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Functional Foods

By Monique Ryan

This article is part one of a two part series on functional foods in your diet. Part two is available here.

The concept of "functional foods" is not really a new one. As early as 1000 BC, Traditional Chinese Medicine has documented both the preventative and therapeutic health effects of foods, and over two thousand years ago Hippocrates said, "Let food be thy medicine." Current scientific knowledge certainly supports the integral role of diet in disease prevention and promoting optimal health.  Driven by the knowledge and demand of health conscious consumers and backed up by technical advances in the food industry, functional foods have become a powerful market force with sales for 2006 estimated at $31.4 billion, according to the trade publication the Nutrition Business Journal. As food companies race to bring more products to the table, our perception of food has clearly reached beyond that of basic sustenance and fuel. 

We all grew up with a few functional foods on the table. In the 1920's iodine was added to salt to prevent goiter, and vitamin A and D fortified milk has been on the market for decades. But even as recently as 1990, the functional food market in the United States was close to non-existent, and fortified foods focused on reducing the risk of disease and deficiencies. Today the concept of functional foods is extremely broad and encompasses not only nutritious natural foods, but also isolated components from these foods that are added to other foods or packaged as dietary supplements, as well as manufactured food components. Fruits, vegetables, and whole grain products found in your daily diet are functional foods, as are green and black tea, probiotic-enhanced yogurts, and margarines containing stanol esters. You may have even started your day with a functional food such as calcium fortified orange juice or gulped down a recovery supplement after a hard workout.

While consumers are extremely receptive to the idea of health enhancing foods, and food companies continue to expand on the huge marketing opportunity behind these products, most researchers agree that functional foods designated with specific health claims should be supported by solid scientific data. As regulated by the Food and Drug Administration (FDA), five types of health-related statements or claims are allowed on food and dietary supplement labels. Manufacturers often step around the more tightly regulated and scientifically sound health claims, such as "may reduce the risk of heart disease." Instead they focus on the "qualified" health claims based on emerging science, or the more ambiguous structure and function claims, such as "promotes a healthy heart."  It is important for you to appreciate that these distinctions are often subtle, and many functional foods have not been clinically tested. We are several years away from having the research needed to support or disprove the suspected health benefits of many currently available functional foods.

Health related statements or claims

Responsibility for regulating claims that allowed on food and dietary supplement labels rests with the FDA, manufacturers, or with advertising, the Federal Trade Commission.

Health claims describe a relationship between a food, food component, or dietary supplement ingredient and reducing risk of a disease or health-related condition. The FDA reviews and authorizes which health claims may be used on a label. To date, the FDA has approved twelve health claims.

Qualified health claims are based on emerging evidence for a relationship between a food or dietary supplement and reduced risk of a disease. For these claims there is not adequate scientific evidence for the FDA to authorize a health claim.

Nutrient content claims indicates that a certain nutrient is present at a certain level in a food, using such terms as freehigh, and low, or comparing the level of a nutrient to that of another food such asmorereduced, and lite. These claims apply to nutrient or dietary substances that have an established daily value.

Structure and function claims describe the effect of nutrient or dietary component on the normal structure and function on the body. Manufacturers are responsible for ensuring the accuracy and truthfulness of these claims, and they are not pre-approved by the FDA. Manufacturers often state in a "disclaimer" that the FDA has not evaluated the claim.

Dietary guidance claims describe the health benefits of a broad category of foods.

Functional foods in our diet

As study results become available, they will not only be published in scientific journals, but also publicized on the front page of your daily newspaper. As an active consumer invested in your training and health, you likely are eager to act on new and promising scientific findings. Let's take a look at some types of functional foods that you are likely to encounter at your local supermarket.

Heart health

Preventing heart disease receives top billing as America's primary health concern, and six FDA approved health claims relate to heart disease. Heart health functional foods provide a full spectrum of choices from whole foods to manufactured food components to supplements.

Whole foods present a potent bag of heart healthy tools that should be part of your daily training diet.Whole grain consumption has been linked with reduced risk of heart disease. Beside fiber, whole grains also provide minerals, antioxidants, and phytonutrients, and plant sterols, which all protect your heart. Good sources include brown rice, whole wheat breads and cereals, buckwheat, millet, bulgur and whole-wheat pasta. Oatmeal deserves special consideration because it is an especially excellent source of beta-glucan, a type of fiber that is "water-soluble," and which binds bile (which contains cholesterol) and dietary cholesterol so that the body excretes it. Water-soluble fiber choicesalso include dried peas and beans, psyllium seeds, flaxseed, and barley. All fruits and vegetables contain water-soluble fiber as well, and some good sources include apples, pears, carrots, broccoli, bananas, cabbage, and berries. In fact, a mere five servings of fruits and vegetables daily can reduce heart disease risk.

Plant sterols and stanols are found naturally in small quantities in many plant foods including fruits, vegetables, nuts, seeds, cereals, legumes, and vegetable oils. Both substances structurally resemble cholesterol and are components of plant cell membranes, and they block absorption of cholesterol from the diet.  Although you consume dietary plant sterols and stanols in your daily diet, the amounts are small and are not likely to have a significant cholesterol-lowering effect. But manufacturers have successfully incorporated them into foods, while keeping their cholesterol-lowering effectiveness. Studies have shown that 1 gram daily can lower cholesterol, with doses of 2 to 3 grams providing the maximum beneficial effect, so higher intakes are not needed. Currently butter spread substitutes which contain plant sterols and stanols are available, and are used by persons with high LDL cholesterol levels. Plant sterols and stanols are also available in softgel dietary supplement form, and marketed as an alternative to individuals with borderline high cholesterol.

Fish is the most potent source of healthy omega-3 fatty acids in the diet, and evidence indicates that these fats fight heart disease. The type of omega-3s in fish, EPA and DHA can also lower blood triglyceride levels and have anti-inflammatory properties. The American Heart Association recommends eating fish at least twice weekly to prevent heart disease, and about 1gram daily of EPA and DHA for persons with heart disease. This dose can be consumed from both fatty fish and under the guidance of a physician in capsule form. The benefits of consuming moderate amounts of fish outweigh the risks of mercury contamination in fish, and fish oil supplements are essentially mercury-free. Besides providing a heart health boost, omega-3 fatty acids may provide benefits for individuals with depression, asthma, rheumatoid arthritis, and age-related maculapathy, the leading cause of blindness in adults. Other than the most potent food source of fish, omega-3s can also be found in flax, walnuts and canola oil.

Gut health

You may have seen a new yogurt on the shelves that claims to "naturally regulate the digestive tract." This yogurt contains a patented strain of a probiotic. The health benefits of probiotics, a live microbial food ingredient, have been known since the 19th century. Along with the more recently discovered prebiotics, which are digested in the colon and act as "food" for beneficial bacteria, probiotics can balance your gut's microflora and enhance the function of the gut and your immune system. The beneficial effects of probiotics are strain specific, and must be demonstrated with clinical trials. Many tested strains are available in pill and powder form, and probiotics are also found in certain yogurts and other cultured dairy products, though not all yogurts contain probiotics. Prebiotics include inulin, fructo-oligosaccharides (FOS), and polydextrose. Besides fortified foods and beverages, prebiotoic food sources include whole grains, onions, bananas, leeks, and artichokes. Because your gut is so essential to your health and immune system, allowing for nutrient absorption, and acting as a barrier to harmful pathogen, many experts believe that probiotics and prebiotics provide too many healthful effects to be passed up.

Antioxidant power

Antioxidants act as potent defenders against harmful free radicals that are thought to play a role in development of cancer, cardiovascular disease, immune dysfunction, macular degeneration and cognitive impairment. While in recent years antioxidant supplements have taken a bit of a scientific beating and high doses of antioxidant supplements are not always a wise choice, maintaining a diet rich in antioxidant foods is highly recommended by several health organizations. There are literally thousands of compounds in foods that act as antioxidants, and they are thought to work best in concert, just as they are found in food. In fact, early promising research on antioxidant power was derived from studies on food intake. 

More commonly known antioxidants besides vitamins, minerals, and carotenoids, include phenols, flavonoids, isothiocyanates and sulfides, which are found in fruits, vegetables, whole grains, nuts and seeds.  Currently the literature indicates at least five daily servings of fruits and vegetables can lead to a reduction in risk of certain cancers and heart disease, and when it comes to these foods, more is better. In the high energy diet of a triathlete, even up to nine servings daily is reasonable.  Variety in choices provides a variety of antioxidants: choose carrots, kale, collards, tomatoes and tomato products, any type of berry, apples, grapes, cauliflower, broccoli, citrus fruits, onions and leeks, and bok choy. Other good antioxidant choices include any type of bean such as kidney, pinto, and black beans, whole grains and both black and green tea.

Research continues to provide even more information on the benefits of fruits and vegetables. While flavonoid-rich foods have been linked to a reduced risk of heart disease, stroke, and cancer, one recent study indicated they may do this by signaling enzyme systems that eliminate mutagens and carcinogens, and by decreasing blood pressure and preventing inflammation. 

Monique Ryan, MS, RD is the author of Sports Nutrition for Endurance Athletes, 2nd edition (VeloPress 2007). Click here to view more about the book or purchase. She was a member of the Athens 2004 Performance Enhancement Teams for USA Triathlon and USA Cycling Women’s Road Team. She is owner of Personal Nutrition Designs and offers her sports nutrition “E Program” at