Influence of habitual diet on antioxidant status: a study in a population of vegetarians and omnivores

Abstract

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 ferricreducing 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 (Pp0.05), a-cryptoxanthin Pp0.05), lycopene (NS), a-carotene (NS) and b-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, a-cryptoxanthin, a-carotene and b-carotene, whereas intake of fruits was positively associated with plasma b-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.

Comparative evaluation of green and black tea consumption on the iron status of omnivorous and vegetarian people

“…However, a recent dietary history investigation with 31 vegetarians (11 males and 20 females) and 58 omnivores (17 males and 41 females), combined with chemical analysis of plasma and erythrocyte samples, did not show any difference in SOD-levels between both groups (Haldar et al, 2007). In contrast to the present study, these authors also did not find a significant difference for levels of GSH.…”

Combined Fruit and Vegetable Intake Is Correlated with Improved Inflammatory and Oxidant Status from a Cross-Sectional Study in a Community Setting

“…TNF-α was not associated with either fruit or vegetable intake. In an interesting comparison of oxidant status of vegetarians and omnivores, Haldar et al found no difference in most measured antioxidant concentrations, including FRAP, between the two dietary groups [17]. …”

Vegetarian Diets and Public Health: Biomarker and Redox Connections

“…Therefore, diet-related effects on individual antioxidants and biomarkers reflecting antioxidant action and oxidative stress within the body are more relevant. Haldar et al showed that plasma carotenoids and ascorbic acid are higher in healthy nonsmoking vegetarians than in omnivores (69). In a Slovakian study, plasma ascorbic acid and b-carotene concentrations were higher ( p < 0.01) in old (aged 60-70 years; n ¼ 33) vegetarians compared to 34 age-matched nonvegetarians (104).…”

“…The atherogenicity of oxidized LDL is greater than native LDL, and LDL of vegetarians was reported to be more resistant to oxidation that nonvegetarians (112). Other biomarkers found to be lower in vegetarians include uric acid (58,69,154,156), and urinary sodium and potassium (156). Uric acid is an independent risk factor for CHD, although the mechanism is unclear (16).…”