Let food be your medicine and medicine be your food. Those were the words of the famed Greek physician Hippocrates nearly 3,000 years ago.
Today you can barely tell the difference between the two. Or at least the line is getting fuzzier.
We've boldly entered an era of nutraceuticals: a blending of foods and pharmaceuticals dubbed "phoods" and "bepherages." These functional foods and beverages are no flash in the pan. They've grown into a huge market estimated at nearly $25 billion and destined to reach $39 billion by 2011, according to the market research publisher Packaged Facts.
It's no longer simply about vitamins and minerals, which are being pumped into an unprecedented range of products - from bottled water and soft drinks to candy bars and cupcakes. Now some of the most popular ingredients in the drugstore are showing up in the grocery store.
Ailment-specific additives are popping out of the supplement aisle and into foods and beverages that are designed to do everything from lower cholesterol to ease arthritis pain.
Functional foods expert John Erdman, a professor of food science and nutrition at the University of Illinois in Urbana-Champaign, thinks this is a positive trend because people would rather eat than take pills.
Drug-leery consumers may find functional foods a more appealing option, said Erdman, citing the problem of compliance with medication.
"Huge numbers of people never even fill their prescriptions," he said.
Not everyone is happy to see the onslaught of functional foods. Some critics are concerned about misleading claims, loose regulations and inappropriate fortification, such as adding nutraceutical ingredients to sugar-laden, low-nutrient products.
If a food didn't start off as a healthful choice, then no amount of fortification will transform it, said Chicago dietitian David Grotto, a spokesman for the American Dietetic Association.
"Not all foods are a worthy delivery system for fortification," said Grotto, who believes functional foods can play a role, but they should not edge out naturally nutrient-rich foods like fruits and vegetables.
Even though he's an ardent supporter of functional foods, Paul Lachance, director of the Nutraceuticals Institute at Rutgers University, acknowledges that the marketing claims can sometimes get ahead of the science.
To help you sort through the array of functional foods available today, check out the accompanying list of some of the most popular nutraceutical ingredients (and where you can find them) to see if they live up to their claims.
Ingredient -- Plant sterols
What it is -- A natural plant compound often extracted from soybeans
The claim -- Lowers blood cholesterol
Where you'll find it -- Nature Valley Healthy Heart chewy granola bar; Oroweat Whole Grain & Oat Bread; Promise activ SuperShots; Yoplait Healthy Heart yogurt
What the experts say -- Plant sterols (or phytosterols) have been widely studied and the cholesterol-lowering benefits repeatedly documented, said Linda Van Horn, professor of preventive medicine at Northwestern University's medical school. Even so, sterol-fortified foods are not a "magic bullet," and they won't negate the detrimental effects of a diet high in saturated fat, trans fat and cholesterol, she said.
Ingredient -- Omega-3 fatty acids
What it is -- A type of fat found in fish and certain plants (flaxseed, walnuts, canola)
The claim -- Promotes heart and brain health
Where you'll find it -- Breyers ice cream; Horizon Organic Milk; Smart Balance peanut butter; Tropicana Healthy Heart orange juice; Yoplait Kids yogurt
What the experts say -- A large portion of the positive heart-health research has looked at eating fish, with a few studies examining fish oil supplements, but there's little hard evidence to support the claims of omega-3 fortified foods, said Van Horn. "It's a leap of logic," she said, to believe these products would offer the same benefits, particularly plant sources of omega-3s (ALA), which are far less potent than fish oils. Omega-3 foods fortified with fish oils (DHA or EPA on the label) come closest to the real thing.
Ingredient -- Epigallocatechin gallate (EGCG)
What it is -- Green tea extract
The claim -- Invigorates metabolism to burn calories and lose weight
Where you'll find it -- Celsius soda; Enviga sparkling green tea
What the experts say -- A few studies have been conducted, but the evidence is weak and inconsistent, said David Schardt, senior nutritionist at the Center for Science in the Public Interest, an advocacy group that sued Coca-Cola and Nestle for "fraudulent" Enviga claims. Three cans a day did help some study participants burn about 100 more calories, but actual weight loss has not been shown.
Ingredient -- Probiotics
What it is -- Live and active bacteria
The claim -- Aids digestive health and immunity
Where you'll find it -- Dannon Danimals; DanActive and Activia; Kashi Vive cereal; Kraft LiveActive cheese; Naked Juice
What the experts say -- Research on these "good bugs" is growing (along with the claims), but it's important to know what you're buying, said dietitian Elisa Zied, a spokeswoman for the American Dietetic Association. Not all yogurts or products with "live cultures" are true probiotics - it depends on the specific strain and level of bacteria. You also need to eat them every day to reap the benefits.
Ingredient -- Chromium
What it is -- A mineral found in meats, whole grains and certain vegetables; sold as chromium picolinate in supplements
The claim -- Promotes weight loss, builds muscle, treats diabetes and lowers cholesterol
Where you'll find it -- Airforce Nutrisoda "Slender"; Dasani Plus water
What the experts say -- Some studies do suggest that chromium may help control blood sugar. In fact, the FDA recently approved a "qualified health claim" related to chromium and the reduced risk of insulin resistance syndrome and possibly diabetes, but concluded the relationship "remains unclear." The weight-loss claims, however, are "preposterous," said Forrest Nielsen, a USDA researcher who specializes in minerals.
Ingredient -- Glucosamine
What it is -- A natural compound in cartilage that's extracted from shellfish shells
The claim -- Eases arthritis pain and supports healthy joints
Where you'll find it -- Airforce Nutrisoda "Flex"; Elations fruit juice; Glaceau Vitamin Water "Balance"; Minute Maid Active orange juice; Vita Splash Joint Support drink mix
What the experts say -- Although widely promoted in arthritis supplements (often combined with chondroitin), the evidence is conflicting, said Dr. Stephen Barrett, a leader against health fraud and founder of QuackWatch.org. Some people have experienced pain relief, but large-scale studies on glucosamine have shown little benefit for arthritis.
Ingredient -- Coenzyme Q10 (CoQ10)
What it is -- A vitaminlike substance also known as ubiquinone (found naturally in meats and fish)
The claim -- Helps prevent and treat heart disease, combats cancer, boosts energy and brain power
Where you'll find it -- Slammers Sport Milk
What the experts say -- Supplement-makers call it a "miracle vitamin," but studies fail to support such a flattering description. It's true that people with heart disease have lower levels of this nutrient in their bodies, but research has not shown any benefit for heart patients.
Janet Helm, a dietitian and nutrition consultant, wrote this article for the Chicago Tribune.