We live in an age when good nutrition practices--eat lots of whole grains, fresh fruits and fresh vegetables; hold the fatty meat and hydrogenated vegetable oils--are simple, straightforward and widely available. But visit a well-stocked health food store, pharmacy or supermarket, and you'd never know it. The variety of dietary supplements can be overwhelming, with dozens of vitamins, minerals and extracts offered alone and in combinations targeted at every possible intersection of age, sex and activity. And that selection is a nutritional desert compared to the tropical rain forestlevel diversity of supplements at more specialized stores.
Dietary supplements are big business in the U.S.: consumer sales in 2006 were estimated at 22.5 billion, with some 60 percent of Americans taking at least a daily multivitamin. But thanks to a regulatory structure designed more to promote the availability of supplements than to ensure that they deliver on their promises, it can seem impossible to figure out what--if anything--you should be taking. The options range from the almost appetizing juxtaposition of garlic, cranberry and soy concentrates to the downright macabre glandulars. And if cramming pituitary, prostate and pancreas extracts into a single pill doesn't count as overkill, then surely another product containing vitamins, minerals and most of the biochemical intermediates of the cellular Krebs cycle must. The skeptical browser could be tempted to ask where to find the snake oil aisle.
But whereas some, or perhaps many, nostrums are no more likely to improve longevity, alertness and athletic performance than the cure-alls of old were to ward off dropsy or nervous agitation, not all can be so easily dismissed. Several once exotic dietary supplements have been the focus of investigation for more than a decade now, and a select few can boast strong quantitative support as a result. One group in particular, the nutraceuticals, is attracting the attention of health advocates and scientists alike.
Occupying a space somewhere between essential nutrients (those nutrients critical to normal health, such as vitamins) and drugs with defined impacts on specific diseases, nutraceuticals are bioactive chemicals derived from foods but taken as supplements at much higher concentrations than diet alone could provide. They include antioxidants from fruits and berries, fatty acids found in cold-water fish, and potentially disease-fighting compounds from common spices such as cinnamon and turmeric. Claims have been made for their role in everything from fighting cancer and cardiovascular disease to maddeningly vague notions about supporting healthy living.
The category of nutraceuticals is really very broad, and their effects may be subtle, says Paul M. Coates, director of the Office of Dietary Supplements (ODS) at the National Institutes of Health. That gives you a clue to the scientific challenges of understanding them. They range from supplements where we don't even know what the active ingredients are to compounds that are well characterized chemically but where the mode of action is still unknown.
To date, most nutraceuticals have been the subject more of marketing hype than of methodical clinical testing, and for many, it is not even yet known whether they provide more benefits than risks for consumers. But in at least a handful of cases, the science is starting to catch up with the health claims.
The Fishy Benefit of OMEGA-3s
Probably the best known of the nutraceuticals, the omega-3 fatty acids, are also the most intensively studied. Like all fatty acids, the building blocks of fats and oils, omega-3s are linear molecules with a carboxylic acid head at one end trailing a tail of linked carbon atoms. Those links can be made with either single (saturated) or double (unsaturated) chemical bonds. Omega-3 simply refers to a double bond in the third position from the end of the carbon tail. Starting with alpha-linolenic acid (ALA, an essential nutrient common in many nuts and vegetable oils), our bodies can synthesize all the omega-3 fatty acids they need to build cell membranes and carry out a host of cellular functions.