When Mother told you to eat your vegetables, she probably didn't know the names of the healthy compounds they contain. Actually, we still don't know them all because we're discovering more all the time. But we do know the names of many of them, and they do some magically healthful things.
"Choose most of the foods you eat from plant sources" is first on the list of dietary recommendation from the American Cancer Society. For many more reasons than cancer prevention, vegetables make a wonderful addition to many food products … and an attractive line on any ingredient statement.
Phytochemicals are nonnutritive plant chemicals that contain protective, disease-preventing compounds. They include antioxidants, beta carotene, lutein, lycopene, zeaxanthin and the flavonoids resveratrol, quercetins, hesperidins, and other compounds such as sulphoraphane, indoles and allium compounds. Every plant has some of these compounds, plus a bonus of fiber.
Although phytochemicals are not considered nutrients, substances necessary for sustaining life, they have been identified as containing properties for aiding in disease prevention, says an Ohio State University Extension fact sheet. Phytochemicals are associated with the prevention and/or treatment of at least four of the leading causes of death in the U.S.: cancer, diabetes, cardiovascular disease and hypertension. They are involved in many processes including ones that help prevent cell damage, prevent cancer cell replication and decrease cholesterol levels.
It's possible some of these phytochemicals have been given too much publicity, giving rise to diets consisting solely of grapefruits or cabbage or other diets that eliminate every vegetable but broccoli. But they all provide important sources of health.
At least 1,000 different phytochemicals have been identified and characterized. They fall roughly into these categories:
- including beta carotene, alpha carotene, lutein, lycopene, cryptoxanthin, canthaxanthin, zeaxanthin and others.
Indoles and allium compounds are plentiful in vegetables as well. Fruits may contain ellegic acids; while their effects on humans are often unclear, some studies indicate they may delay aging.
There has been continual research on these compounds since the discovery of vitamins during the 1930s and 1940s. Individual compounds have been isolated, and methods have been developed to synthetically produce them in quantity. But there is a belief that nears consensus that phytochemicals may be more easily used by humans as components in vegetables and fruits than as isolated chemicals. There also is growing agreement that foods contain more phytochemicals that have not yet been identified, but that may be healthy.
The mechanisms of action for all phytochemicals are not totally clear, and some of the claims are not researched well enough to convince the Food and Drug Administration to allow claims for the phytochemicals instead of the food that contains them. Hence, the 5-a-day campaign and the emphasis on the healthy eating pyramid call for eating a wide variety of whole vegetables and fruits instead of supplements containing specific phytochemicals.
Tomatoes make a splash
Lycopene caused a big splash about five years ago when it was found to have a connection with prostate cancer. Lycopene is a carotenoid responsible for the red color of tomatoes, peppers and other red fruits and vegetables. Research sponsored by Pittsburgh's H.J. Heinz Co. (www.heinz.com) and the Harvard Medical School indicates that consumption of tomatoes (including ketchup) showed a measurable reduction in the risk of prostate cancer.
Unlike many beneficial food components, lycopene has been shown to be more available to the human body in its processed form. Heating not only doesn't destroy lycopene, but the temperature changes involved in processing make it more easily absorbed by the body.
|This graphic from Heinz illuminates the health benefits of lycopene for both men and women. To access the PDF that is the source of this graphic, click here.
Heinz has taken this science a step up the food chain by breeding tomato types that contain extra lycopene. The tomato varieties are produced by classic selective breeding techniques, so they are not genetically modified. Rich Ozminkowski, Heinz's plant breeder, notes, "Tomatoes from the Heinz seed program are bred especially for the tomato processing market, and they also have resistance to plant diseases. They are deep red, with thick enough walls to make mechanical harvesting appropriate."
Plant breeding is one approach to improving both diets and bottom lines, but a number of companies are looking at other ways of increasing carotenoids in various fruits and vegetables. Some products may be produced using gene insertion (biotechnology).
For instance, Sungene Corp. recently filed a patent application for a method of producing plants with increased amounts of vitamin E. Several companies and universities have been working on increasing vitamin A content in rice and other grains and vegetables. There are several reasons for working on these products: One is the search for better and healthier vegetables that will have improved sales, but there also are grants to be won from sources such as Microsoft (through its Bill and Melinda Gates Global Challenges program) aimed at improving diets in underdeveloped countries.