Sept 1. 2009 (Sciencedaily.com)—Antioxidant supplements do not appear to be associated with an increased risk of melanoma, according to a new report.
A recent randomized trial of antioxidants for cancer prevention found that daily supplementation with nutritionally appropriate doses of vitamins C and E, beta carotene, selenium and zinc appeared to increase the risk of melanoma in women four-fold, according to background information in the article. Because an estimated 48 percent to 55 percent of U.S. adults use vitamin or mineral supplements regularly, the potential harmful effects of these nutrients is alarming, the authors note.
Maryam M. Asgari, M.D., M.P.H., of Kaiser Permanente Northern California, Oakland, and colleagues examined the association between antioxidants and melanoma among 69,671 women and men who were participating in the Vitamins and Lifestyle (VITAL) study, designed to examine supplement use and cancer risk. At the beginning of the study, between 2000 and 2002, participants completed a 24-page questionnaire about lifestyle factors, health history, diet, supplement use and other cancer risk factors.
Intake of multivitamins and supplements during the previous 10 years, including selenium and beta carotene, was not associated with melanoma risk in either women or men. The researchers also examined the risk of melanoma associated with long-term use of supplemental beta carotene and selenium at doses comparable to the previous study and found no association.
“Consistent with the present results, case-control studies examining serologic [blood] levels of beta carotene, vitamin E and selenium did not find any association with subsequent risk of melanoma,” the authors write. “Moreover, the Nurses’ Health Study reported no association between intake of vitamins A, C and E and melanoma risk in 162,000 women during more than 1.6 million person-years of follow-up.”
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July 31, 2009 (Mercola.com)—Tomatoes are a good source of the antioxidants lycopene and beta-carotene. But if you eat a tomato without adding a little fat, your body is unlikely to absorb all these nutrients.
Scientists recruited graduate students to eat bowls of salad greens with tomatoes and various types of salad dressings. The researchers put IV lines into the participants’ veins and drew blood samples before and after they’d eaten the salads in order to get precise measurements of the absorption of nutrients.
When researchers went back and analyzed the blood samples, they realized that people who had eaten fat-free or low-fat dressings didn’t absorb the beneficial carotenoids from the salad. Only when they had eaten the oil-based dressing did they get the nutrients.
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NPR July 27, 2009June 19, 2009 (Medscape.com)— Intake of vitamins C and E and beta-carotene is not linked to the risk for type 2 diabetes in women at high risk for cardiovascular disease, according to the results of a large, randomized, double-blind, placebo-controlled trial reported in the June 2 Online First issue of the American Journal of Clinical Nutrition.
“Vitamin C, vitamin E, and β-carotene are major antioxidants and as such may protect against the development of type 2 diabetes via reduction of oxidative stress,” write Yiqing Song, from Harvard Medical School in Boston, Massachusetts, and colleagues. “Evidence from basic research and observational studies has suggested that oxidative stress elicits systemic inflammation, promotes endothelial dysfunction, impairs pancreatic β cell insulin secretion, and interferes with glucose disposal in peripheral tissues, thereby accelerating the development and progression of type 2 diabetes.”
For full article see link above.