The trouble, argues Lynne McTaggart, editor of the monthly U.K. health journal What Doctors Don’t Tell You, is that even if you do eat your broccoli, you may not be getting what you need. “Food isn’t as nutritious as it once was,” she says, pointing to research that shows a decrease in nutrient levels in produce compared with what was harvested a few decades ago. In 2007, Brian Halweil, a researcher at the Worldwatch Institute, reviewed several projects that examined nutrient levels in produce. In a report published by the Organic Center of Boulder, Colorado, he concluded that breeding for high yields has diluted the nutritional quality of the plants we eat. According to data collected by government agencies in the U.S. and U.K., modern harvests are lower in many nutrients than those in the 1940s and 1950s, including magnesium, iron, potassium, calcium, riboflavin and vitamin C.
Halweil also highlighted research suggesting that conventional produce grown in poor soils and bathed in synthetic fertilizers may have lower levels of nutrients than that grown with organic techniques. But even organic food has come in for criticism; a report commissioned by the U.K. Food Standards Agency (FSA) found no substantial difference in nutritional content between organic and conventional food, a finding strongly contested by the Organic Center, the U.K. Soil Association and others.
Still, to many nutrition experts, supplements make a lot of sense. “Even people who consistently eat well can benefit from supplementation,” says Weil. “Optimal intakes of key nutrients, in amounts sufficient to enhance health beyond the prevention of deficiency states, can be difficult to obtain through diet alone.”
At least 50 percent of Americans take a supplement, and 35 percent take a multivitamin. Some 4.2 billion dollars was spent on multivitamins alone in 2005, according to the Council for Responsible Nutrition, a trade organization representing the industry.
Vitamins were first discovered in the early 20th century when researchers observed that certain diseases correlate to dietary patterns. In the 1920s and 1930s, scientists discovered links between scurvy and vitamin C, blindness and vitamin A, and rickets and vitamin D. Though these deficiency diseases have been virtually eliminated in the West, through fortification and greater access to a wide variety of nourishing foods, many people in the developing world still suffer from them.
While most Americans don’t suffer from overt deficiencies, Ames argues many of us may be suffering from less obvious shortfalls that contribute to disease.
“There are many diseases that could be a long-term consequence of being deficient in one or more nutrients,” argues McTaggart. “There’s a lot of evidence that vitamins and minerals protect against illness. Jeffrey Blumberg, a nutrition scientist at the Tufts University Friedman School of Nutrition Science and Policy in Boston, Massachusetts, points out that certain benefits of supplements have been verified. Vitamins A, C and E can help protect against age-related macular degeneration, an eye condition that can lead to blindness, and vitamin E boosts immune response. A combination of vitamin E and selenium looks promising for fending off cancer, he says, and several studies support a potential cancer prevention benefit from vitamin D and calcium. There’s also good research linking omega-3 supplements to reduced risk of heart attack.
Which supplements should we choose? How many should we take? And in what form should we take them? The key to choosing supplements is to analyze your own dietary patterns, says Yale’s David Katz. “Look at your diet and figure out what nutrient you might be deficient in. Make the supplements match the likely pattern of gaps in your diet.”
Next: Which supplements to choose and which to avoid