Reducing Radicals with Lycopene

Lycopene, a red-colored carotenoid antioxidant found in many fruits and vegetables, scavenges free radicals. Current research characterizes it as highly potent in quenching the very damaging singlet oxygen. As such, it can protect cells from damage by free radicals and may help prevent chronic illnesses such as cancer and cardiovascular disease.

Tomatoes and tomato products, the best-known and most-widely consumed sources of lycopene, comprise about 80% to 90% of dietary intake. Other sources include watermelon, pink grapefruit, pink guava, papaya, apricots and blood oranges.

The plant cultivars, growing conditions and processing influence the actual amount and bioavailability of lycopene. In general, redder means higher in lycopene. Cooked tomato products are higher in lycopene than raw items; more of this antioxidant becomes bioavailable as heat releases it from cells and changes its isomeric form. Additionally, a small amount of fat enhances absorption.

Among fresh produce, watermelon is the leading source of lycopene and, according to a recent USDA Agricultural Research Services study, the antioxidant is as bioavailable as when it is found in tomato juice. A 2-cup serving of watermelon (280 grams) has 15 to 20 mg of lycopene, a fresh medium tomato (123 grams) has 4 mg, and 1 cup of tomato juice (250 ml) has 25 mg.

Lycopene appears beneficial in the prevention of many cancers. Observations about tomato-product consumption and the incidence of prostate cancer first led to studies that associated lycopene with the potential for cancer prevention. Other epidemiological and laboratory research from around the world indicates that lycopene may play a similar role in lung, stomach, liver, breast, ovarian, endometrial and skin cancer. However, research with rodents given pure lycopene indicates that other tomato components may also play a role in protecting against prostate carcinogenesis. And research with prostate cancer cells from Ben-Gurion University, Be’er-Sheva, Israel, shows a decrease in growth with lycopene plus phytoene and phytofluene, but not with lycopene alone or phytoene and/or phytofluene alone, thus suggesting a synergistic effect among these tomato components.

High lycopene blood levels are also associated with lower incidence of heart attacks and stroke. However, a study using tomato extract indicated that the complex of carotenoids and other phytochemicals in tomatoes is more effective than lycopene alone in reducing the oxidation of LDL-cholesterol, which contributes to the build-up of plaque in blood vessels (Antioxidant and Redox Signaling, Fall 2002). Another study with hypertensive subjects indicates that tomato extract may help lower blood pressure (American Journal of Hypertension, April 2001 supplement).

New research is looking beyond cancer and cardiovascular-disease prevention for other ways that lycopene and tomatoes may contribute to health. On April 1-2, 2003, at The International Ceres® Forum on “Examining Health Benefits of Lycopene from Tomatoes” held in Washington, D.C., researchers reported a positive association between tomato-extract consumption and increased male fertility among infertile men. Other research was presented on a possible role for lycopene in decreasing the oxidative stress that can contribute to bone loss in post-menopausal women.

Incorporating lycopene in the diet is as easy as using more tomato products and fruits, such as watermelon and pink grapefruit, as part of the recommended five servings of fruits and vegetables per day. Data on the amount of lycopene needed for health is insufficient to determine an RDA, but large population studies suggest that about 6.5 mg/day is protective. Estimates on consumption levels range from less than 0.5 to 16.0 mg/day, with a median intake of 3.6 mg/day.

Ingredients with standardized lycopene are available for formulating products. For example, the non-GMO tomato extract Lyc-O-Mato® from LycoRed Natural Products Industries Limited, Be’er-Sheva, Israel, contains the naturally occurring carotenoids lycopene, phytoene, phytofluene and beta-carotene, plus tocopherols and other bioactive phytochemicals in tomato oil. It is standardized to 6% lycopene. Research demonstrates that subjects achieve higher serum lycopene levels with this product than with tomato ketchup when given on a lycopene-equivalent basis. A variety of dietary supplements and a number of clinical research studies currently use this ingredient as a lycopene source. For functional foods, LycoRed manufactures tomato extracts standardized to 3.0% to 5.0% lycopene, microencapsulated beads with 5.0% lycopene and dehydrated, fibrous tomato-pulp concentrate with 0.8% to 1.3% lycopene.

FDA granted synthetic lycopene from Roche Vitamins, Inc., Parsippany, NJ, GRAS status in April 2002. Available in water-dispersible and oil-soluble forms with 10% lycopene, it lends itself to use in many products, such as nutritional bars, beverages, meal-replacement drinks, salad dressings, yogurts, desserts and soups. According to company literature, synthetic lycopene will not affect the taste of foods and beverages, and is stable and easy to process. However, the oil-soluble form is dark red, and water-dispersible forms yield orange-red to red colorations in solution.

Consumers’ concerns for prevention of cancer, cardiovascular disease and osteoporosis peaks interest in formulating products with added lycopene. However, questions remain on whether the complex of lycopene and other tomato phytochemicals is necessary for health benefits, and if other food sources of lycopene offer the same potential for health benefits. A leading expert in lycopene research, A. Venket Rao, Ph.D., professor emeritus, department of nutritional sciences, University of Toronto, says: “The evidence is looking good as to the benefits of lycopene. We now recommend that people should get 5 to 10 mg/day, which is very achievable with everyday foods, especially tomato products.”

Angela M. Miraglio, M.S. ([email protected]), is also a registered dietitian and Fellow of the American Dietetic Association from Des Plaines, IL. Her firm, AMM Food & Nutrition Consulting, provides communications and technical support to food and beverage companies and associations