New findings from UCLA indicate that Lutein -- a carotenoid recently discovered in California avocados and found in green vegetables -- can help protect against prostate cancer. This study was presented at the American Institute of Cancer Research (AICR) meeting in July 2001 in Washington D.C.
In recent studies, Lycopene -- a carotenoid found in tomatoes -- was associated with a reduced risk of prostate cancer, but lutein had not been linked to prostate cancer prevention until now.
According to Dr. David Heber, director of the UCLA Center for Human Nutrition and author of "What Color Is Your Diet," the study initially focused on a rural area of China, which had a low incidence of prostate cancer despite a diet virtually free of lycopene (due to lack of tomato intake) but rich in lutein (due to a high consumption of green vegetables). The study was then expanded to include Chinese American men and Caucasian men.
UCLA lab tests showed that lutein reduced prostate cancer cell growth by 25 percent while lycopene reduced cell growth by 20 percent. When lutein and lycopene were combined, prostate cancer cell growth was reduced by 32 percent. Thus indicating that both nutrients together help protect against prostate cancer better than either nutrient alone.
The studies have shown that unless vegetables are consumed along with healthy fats—such as avocado oil, for example—the body can barely absorb the lycopene and get them into the bloodstream where they work their magic.
"Lutein and lycopene in combination appear to have additive or synergistic effects against prostate cancer," said Heber. "Our results suggest that further studies should be done to investigate the nutrient-nutrient interactions of lutein and lycopene at a subcellular and molecular level."
Traditionally, lutein has been found in green vegetables such as parsley, celery and spinach but was recently discovered in the avocado fruit. In fact, research shows that avocados are the highest fruit source of lutein among the 20 most frequently consumed fruits.
In addition to the new prostate cancer findings, lutein is also known to protect against eye disease such as cataracts and macular degeneration, the leading cause of blindness in the elderly. Studies from around the world sponsored by the AICR have shown that individuals eating 400 to 600 grams per day (more than one pound) of fruits and vegetables reduce their risk of certain cancers by 50 percent.
Food scientist Steven Schwartz at Ohio State University and his team wanted to see if avocado, a great source of heart-healthy monounsaturated fat, could match the antioxidant-boosting properties of salad dressing. They gave 11 volunteers salsa or salad with or without avocado, and then tested their blood periodically for 9 1⁄2 hours. They found that when volunteers ate avocado, concentrations of lycopene, beta carotene and alpha carotene in their blood ranged from 2 to 15 times higher than when the dishes were eaten without avocado. They also found that the fat in the fruit was indeed behind the increased absorption.
“The responses were really dramatic. We found that half of an avocado fruit (about 2 1⁄2 ounces) with a typical salad is sufficient” to increase carotenoid absorption, says Schwartz. There are also added benefits to consuming avocados—dietary fiber and other nutrients like folate and vitamin K.
California avocados fall in the green-yellow group and contain such vital nutrients as vitamin E, which helps "mop up" free radicals that can damage cells and lead to disease; glutathione, which functions as an antioxidant like vitamin E; beta-sitosterol, which helps lower blood cholesterol; and the recently discovered lutein, now linked to prostate cancer and eye disease prevention.
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Resource
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• American Institute of Cancer Research (AICR) meeting - July 2001
• Robert O. Young D.Sc., Ph.D: Articles of Health: Preventing and Reversing Cancer with Fruit and Vegetables High in Lycopene & Lutein – November 20, 2012
• USDA Nutrient Database: Lutein
• "Journal of the American College of Nutrition"; Lutein and Zeaxanthin and Their Potential Roles in Disease Prevention; Judy D. Ribaya-Mercado, ScD; 2004
• The World Cancer Fund and The American Institute for Cancer Research, Diet and Cancer Report - http://www.dietandcancerreport.org/cancer_resource_center/er_graphics.php?-skip=175&-max=25
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