[Effect of vitamin C supplementation on oxidative stress markers following 30 minutes moderate intensity exercise in healthy young women]

There is no convincing evidence about the role of vitamin C in preventing exercise induced oxidative stress. The aim of this double blind randomized controlled trial was to determine the effect of vitamin C supplementation on oxidative stress, following 30 minutes of moderate intensity exercise. Forty-nine healthy, young female university students were randomly assigned into the 500 mg/day vitamin C supplement [n=25] and the placebo [n=24] groups for two weeks. Before supplementation and on the day after the intervention period, fasting blood samples were taken. Then all participants ran [5-6 km/h] for 30 minutes. A third set blood samples were taken at the end of exercise. Plasma malondialdehyde [MDA] and vitamin C were measured with the HPLC method. Plasma total glutathione was measured with the glutathione assay kit. No significant differences were observed in the demographics, vitamin C intakes before intervention between groups at baseline. Plasma MDA levels decreased and plasma total glutathione increased significantly in both groups. No significant differences were observed between groups after exercise. There were significant differences in plasma vitamin C concentrations after intervention and exercise between groups. Vitamin C supplementation [500 mg/day] for two weeks does not affect oxidative stress markers following moderate intensity exercise in healthy young women

Effects of soy protein isoflavones on serum lipids, lipoprotein profile and serum glucose of hypercholesterolemic rabbits

The main objective of this research was to determine the effects of soy protein isoflavones on serum lipids, lipoproteins and fasting blood sugar levels in hypercholesterolemic rabbits. Twenty-four male New Zealand rabbits received the basic pellet diet for two weeks and were then placed on a hypercholesterolemic diet [pellets plus 1% cholesterol] for three weeks. After elevation of total cholesterol, the rabbits were randomly allocated into four experimental groups. Groups 1 to 3 received 100g soy protein containing 200mg [SPI+], 100mg [SPI50%] soy protein diet and without isoflavones [SPI-], respectively, for six weeks. The fourth group was kept on the hypercholesterolemic diet [HC]. Findings showed that cholesterol rich diet produced significant increase in total, LDLand HDL-cholesterol concentrations. In SPI+ group these parameters remained unchanged, compared with SPI- and SPI50% groups [P<0.0001]. HDL-cholesterol was significantly elevated after administration of HC diet and remained high [almost three fold] in all soy diets relative to baseline. However, its level was significantly lower in SPI50% compared with SPI-group [p<0.01]. Triglycerides and VLDL concentrations were significantly increased in SPI50% compared with baseline and HC groups [P<0.03]. Fasting blood sugar levels were not changed in all soy treatment groups. These results suggest that intact soy protein isoflavones ameliorate the lipid profile in spite of high-cholesterol intake, but has no obvious effect on blood sugar levels and can therefore be useful in hyperlipidemias especially when cholesterol intake is simultaneously decreased. Moreover, there is no direct doseresponse relationship between soy isoflavone content and its lipid-lowering effect