One of the standard assumptions that I've had about the vegetarian and vegan diets is that they provide significantly more antioxidants than a Standard American Diet. But we have a study that shows that omnivores (meat eaters) are comparable to vegetarians (eggs and dairy) in terms of anti-oxidant status. I'd like to see the study repeated with just vegans.
Eur J Clin Nutr. 2007 Aug;61(8):1011-22. Epub 2007 Feb 14.
Influence of habitual diet on antioxidant status: a study in a population of vegetarians and omnivores.
Haldar S, Rowland IR, Barnett YA, Bradbury I, Robson PJ, Powell J, Fletcher J.
Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster, Coleraine, County Londonderry, UK. firstname.lastname@example.org
BACKGROUND: Antioxidant status can be used as a biomarker to assess chronic disease risk and diet can modulate antioxidant defence.
OBJECTIVE: To examine effects of vegetarian diet and variations in the habitual intakes of foods and nutrients on blood antioxidants.
SUBJECTS AND SETTING: Thirty-one vegetarians (including six vegans) and 58 omnivores, non-smokers, in Northern Ireland.
DESIGN: A diet history method was used to assess habitual diet. Antioxidant vitamins, carotenoids, uric acid, zinc- and ferric-reducing ability of plasma (FRAP) were measured in fasting plasma and activities of glutathione peroxidase (GPX), superoxide dismutase (SOD) and glutathione S-transferase (GST) and level of reduced glutathione (GSH) were measured in erythrocytes
RESULTS: Vegetarians had approximately 15% higher levels of plasma carotenoids compared with omnivores, including lutein (P< or =0.05), alpha-cryptoxanthin P< or =0.05), lycopene (NS), alpha-carotene (NS) and beta-carotene (NS). The levels/activities of all other antioxidants measured were similar between vegetarians and omnivores. Total intake of fruits, vegetables and fruit juices was positively associated with plasma levels of several carotenoids and vitamin C. Intake of vegetables was positively associated with plasma lutein, alpha-cryptoxanthin, alpha-carotene and beta-carotene, whereas intake of fruits was positively associated with plasma beta-cryptoxanthin. Intake of tea and wine was positively associated with FRAP value, whereas intake of herbal tea associated positively with plasma vitamin C. Intakes of meat and fish were positively associated with plasma uric acid and FRAP value.
CONCLUSIONS: The overall antioxidant status was similar between vegetarians and omnivores. Good correlations were found between intakes of carotenoids and their respective status in blood.