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By Frances Katz, Senior Technical Editor | 03/30/2006
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:
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.
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.
Lycopene is available in a concentrated form by several companies, including LycoRed, an Israeli company that recently received FDA approval for the use of the product as a food coloring. “Tomat-O-Red is produced with lycopene extracted from a proprietary variety of non-GMO, lycopene-rich tomatoes,” according to Morris Zelkha, CEO of LycoRed (www.lycored.com), which has a U.S. office in Fairfield, N.J. “LycoRed’s is produced using a unique, patent-protected production that produces a taste-masked product that is pH stable.” It’s considered generally recognized as safe by FDA.
Tomatoes are also a major source of lutein and zeaxanthin, antioxidants found in a variety of colorful vegetables including spinach, squash and romaine lettuce. Both have shown great promise in improving eye health.
Lutein acts as a filter against the blue light spectrum, protecting the eye from macular degeneration and cell damage. In particular, lutein may reduce the risk of age-related macular degeneration (AMD), the leading cause of vision loss among older Americans. While lutein still does not have a government-accepted health claim, more than 300 peer-reviewed studies have connected lutein with benefits in eye, skin and heart health, as well as for different types of cancer, immune problems and diabetes.
The Lewin Group, a healthcare consulting group headquartered in Research Triangle Park, N.C., evaluated studies on the effects of lutein on vision health. Results announced last November estimated a five-year (2006-2010) net savings of $2.5 billion from the reduced incidence of adult macular degeneration (AMD) through the daily intake of 6-10mg of lutein combined with zeaxanthin. Across the five year period, 98,219 people could avoid costs associated with advanced AMD, Lewin Group estimated.
“We believe this study is a significant addition to the large and growing body of science supporting lutein’s important role in human nutrition,” says Rod Ausich, president of Kemin Health Products (www.kemin.com), Des Moines, Iowa. Kemin’s lutein product is made from marigold petals.
Zeaxanthin is a yellow-colored lipid-soluble xanthophylls — an oxidized hydroxy derivative of beta-carotene. Zeaxanthin also can be derived from paprika. Such a product made by Kalsec Co. (www.kalsec.com), Kalamazoo, Mich., is used by ZeaVision LLC in nutritional supplements for ocular health with a dosage of 4 mg or less, according to Gary Hainrihar, Kalsec’s vice president of sales and marketing.
Flavonoids are worth noting also. They include quercetin, xantholumol, ispxanthohumol, genisten, and a couple of pro-oxidant flavonoids, chalconaringenin and naringenin.
Different kinds come from a wide range of plants, from the isoflavones in soy and other beans to the quercetin in red fruits to types found in herbs and spices. They contribute to an antioxidant defense system, providing activity that may be like vitamin E, as chain-breaking antioxidants in liver microsomal membranes.
How effective flavonoids are depends on the position of hydroxyl groups and other features in the chemical structure. Quercetin, the most abundant dietary flavonol, is a potent antioxidant because it has all the right structural features for free radical scavenging activity. Apples, onions and other vegetables contain significant quantities.
Other flavonoids include epigallocatechin gallate (ECGC), a component of green tea, which has been shown in some tests to have activities against certain cancers. ECGC is as much as 100 times more powerful an antioxidant as vitamin C, and 25 times more powerful than vitamin E. This may explain the popularity of green tea and its use as a beverage base in a number of products. ECGC also may account for the antibacterial properties of green tea.
Chocolate contains many of the same flavonoids found in tea. The darker the chocolate, the more flavonoids present. Cocoa includes a number of phytochemicals, including several different flavanols, catechins, and cyanadins. But current interest is in the polyphenols in cocoa, which appear to have a clinical effect on cholesterol and cardiovascular health.
NOTE TO PLANT OPS
Keeping these plant components in the final product may require some tuning of your processes. Recent studies of the effect of processing techniques on the antioxidant quality of vegetable ingredients indicate it’s important for the plant guys to understand the chemistry of these products.
In studies reported at the Institute of Food Technologists’ 2005 annual meeting, garlic processed by dry heat, boiling and steaming before drying showed large differences in the electron-donating ability of the final garlic product. Electron-donating ability measures the effectiveness of the antioxidant effect. It’s believed other vegetables are similarly affected.
Antioxidants can enhance the effectiveness of certain vitamins (such as folate), so it’s important that the antioxidant effects not be lost by steam, extra moisture or metallic ions from processing equipment. Check for exposed surfaces, wear on stainless steel piping and inadvertent addition of steam in order to retain the effectiveness of natural antioxidants.
NOTE TO MARKETING
Products that include phytochemicals may or may not be permitted a health claim. There are just 12 FDA-permitted health claims, and only one (plant sterol/stanol esters and heart disease) directly mentions a phytochemical. But many more health claims generally suggest a connection by recommending fiber or specifically the consumption of fruits and vegetables.
However, with or without a health claim, products that label with phytochemicals will get noticed by interested consumers who have a growing understanding of their benefits.
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