Even if you don't grow your own vegetables, you see their fall colors come alive in farmers’ markets and supermarket bins: deep orange winter squash and carrots, red and yellow beets and Swiss chard, purple onions, potatoes and cabbages.
Study after scientific study has confirmed that people who eat more fruits and vegetables, particularly the deeply colored varieties, suffer less heart disease, cancer, diabetes, osteoporosis, and age-related neurological decline.
Plants: the master chemists
“Plants are the master chemists,” says Mary Ann Lila, who directs the Plants for Human Health Institute at North Carolina State University. “Because plants can't move around, they have to manufacture what they need, not merely to grow, but to defend, protect, and heal themselves. It makes sense that the compounds plants produce in response to stress would help a human under similar circumstances.”
Increasingly, scientists have begun to focus on the health-promoting benefits of pigments, the light-harvesting molecules plants manufacture that selectively absorb certain bandwidths of visible light and reflect the others.
Pigments serve and protect plants
Earth’s first plant pigment—chlorophyll—initiates photosynthetic reactions that enable plants to produce their own food, and in the process produce all the food and the all the oxygen that sustain the animal life on the planet.
But other pigments (orange, red, yellow, and purple) protect plants from excessive, tissue-damaging solar radiation and environmental stress; defend against attacks by microbes, insects and animal predators; heal damaged tissues, serve as growth regulators, and probably act in many other ways still undiscovered.
Why not simply extract the pigments and put them into pills?
“Well, there's a lot of research heading in that direction,” says James Joseph, a neuroscientist and senior researcher at the Tufts University Human Nutrition Research Center on Aging in Boston. “But when you start taking these things apart, the compounds don't act like they do in the whole food. In fact extracts can even produce the opposite effect, especially in high doses.”
“If you take something out of a plant and put into a pill, it's more expensive, probably less effective, and possibly dangerous,” says retired USDA ethnobotanist James A. Duke, author of 30 books and a huge phytochemical (chemicals plants have manufactured naturally) database, and an authority on medicinal plants. “Plus it's not occurring with its natural synergists. Most phytocompounds work together, with synergistic or additive effects.
“But you can't overdose on vegetables,” Duke says.“Variety is the key. Get the most variety of colorful fruits and vegetables you can the most cheaply.”
There's a lot at stake.
Chronic diseases, responsible for 70 percent of American deaths, currently afflict 40 percent of Americans and 80 percent of older Americans. Half the nation's elders suffer from two or more chronic health conditions.
Yet just over a quarter of Americans eat the current USDA recommendation of three servings of vegetables a day, and most experts call for nine servings to get the maximum benefits. Children ages two to 18 eat even less: dark green or orange vegetables make up only eight percent of the veggies children eat and fried potatoes account for nearly half.