Oxidative Stress in Vegetarian Diets: Take Two
This is the second part to yesterday’s Vegetarian Diet, Glutathione and Oxidative Stress.
A 2012 study from Korea compared the antioxidant status of 45 vegetarians (10 vegans and 35 lacto-ovo vegetarians) to 30 omnivores (1). The vegetarians had to have been vegetarian for at least 10 years and they were mostly Seventh-day Adventists. The vegetarians consumed animal products only occasionally. They had to be without chronic disease and not taking antioxidant supplements, could not be smokers, and could not drink one or more alcoholic beverages per week.
The vegetarians ate a diet of 66% carbohydrate, 19% protein, and 15% fat (versus 60%, 17%, and 25%, respectively, for omnivores). The vegetarians ate about the same amount of calories as omnivores (1,832 vs. 1,790). There was no iron-deficiency anemia. The groups were similar in weight, height, body mass index, and blood pressure but the vegetarians had a lower body fat percentage. Vegetarians had average cholesterol levels of 174 mg/dl, compared to 193 mg/dl for omnivores.
Antioxidant status findings: Vegetarians had significantly lower amounts of diacron reactive oxygen metabolites, which is a reflection of oxidative stress. From what I can tell, by “oxidative stress” they mean “oxidative damage.”
Despite the difference in oxidative stress, both groups had the same levels of biological antioxidant potential. They measured a number of other antioxidant enzymes, including glutathione peroxidase, and found them to be the same in both groups. The authors suggest that the reason for the lack of differences in antioxidant capacity between diet groups could be a tendency to maintain homeostasis.
Body fat, total cholesterol, and LDL cholesterol were significantly and positively associated with reactive oxygen metabolites level.
In this study, vegetarians suffered less oxidative stress (or damage). So far, Kiefer appears to be 0 for 2.
1. Kim MK, Cho SW, Park YK. Long-term vegetarians have low oxidative stress, body fat, and cholesterol levels. Nutr Res Pract. 2012 Apr;6(2):155-61. Epub 2012 Apr 30. | link