A study that appears in the May 4 2005 issue of the Journal of Agricultural and Food Chemistry shows that green and black tea both help prevent cataracts in diabetic rats.
Dr Vinson, of the University of Scranton, PA, who is the lead author of the report, commented, "Most people, scientists included, believe that green tea has more health benefits than black tea." Previous research conducted by Dr Vinson found that green and black tea are equally effective at inhibiting atherosclerosis, which is one of cardiovascular disease's major risk factors.
The researchers induced type 1 diabetes in 25 rats, and divided them to receive green tea, black tea, or no tea for three months. An additional eight rats without diabetes were used as controls. The amount of tea the animals received was equivalent to less than five cups of tea per day for a human. Blood samples were analyzed before and after the treatment period for glucose, sorbitol, protein, oxidative damage, glycation, cholesterol and triglycerides.
All diabetic animals were found to have significantly elevated glucose in the lenses of their eyes and in blood plasma at the study's conclusion. Cataract formation was significantly reduced in the lenses of the rats who received both green and black tea compared to the rats who did not receive tea. It was determined that green and black tea retarded the development of cataracts by lowering glucose, which affects pathways that increase diabetic complications, including cataracts. The reduction in glucose of 28 to 32 percent in rats who were given tea was comparable to the 29 percent reduction associated with tea drinking in a human diabetic study.
The authors recommend, "Teas should be investigated further for possible prevention therapy and adjunct therapy in human diabetes."
Journal of Agricultural and Food Chemistry; May 4 2005