November 3, 2004 -- Volunteers who ate vegetables consistently for two weeks as part of a nutrition study showed a significant increase in blood levels of vitamin C and a decrease in key stress molecules associated with health impairment. The findings from this study funded in part by the Agricultural Research Service appear in today's issue of the Journal of Nutrition.
The study was conducted by Antonio Martin, a physician specializing in nutrition and inflammatory responses, along with colleagues in academia and medicine. Martin is with the Nutrition and Neurocognition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Mass.
The researchers fed 12 healthy volunteers--six men and six women--two bowls (17 ounces, total) of gazpacho every day for two weeks. The antioxidant-rich soup was made from tomatoes, cucumbers, green peppers, olive oil, onions and garlic. Blood samples for each volunteer were taken prior to soup consumption and on the seventh and fourteenth days of the study. Starting on the seventh day, levels of vitamin C in volunteers' blood samples were found to have increased by 27 percent in men and 22 percent in women, and they remained elevated for the rest of the study.
The stress molecules that were measured during the study are secreted by the body as a normal response to stress. But continuous high blood levels of these chemicals increase vulnerability to illness due to inflammation and oxidative stress.
One of the stress molecules measured, uric acid, was reduced by 18 percent in the male volunteers and by 8 percent in the females. High blood levels of uric acid, which causes gout, have been associated with an increased risk of cardiovascular disease.
Three of the other stress molecules measured were also found to be significantly decreased after soup consumption.
The study is one of the few examining the effects of dietary intervention, rather than supplementation, on circulating levels of antioxidants and inflammatory biomarkers in healthy volunteers.
ARS is the U.S. Department of Agriculture's chief scientific research agency.
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