Elsevier

Nutrition

Volume 20, Issue 10, October 2004, Pages 863-866
Nutrition

Applied nutritional investigation
Effects of a long-term vegetarian diet on biomarkers of antioxidant status and cardiovascular disease risk

https://doi.org/10.1016/j.nut.2004.06.006Get rights and content

Abstract

Objective

We compared plasma biomarkers of antioxidant status, oxidative stress, inflammation, and risk for coronary heart disease in long-term vegetarians and age- and sex-matched omnivores.

Methods

Thirty vegetarians (mean age ± standard deviation: 44.2 ± 9.0 y) were recruited. The subjects had been vegetarian for 5 to 55 y (21.8 ± 12.2 y). The control group comprised 30 adults selected by age-stratified sampling from a community health project (mean age: 44.0 ± 9.2 y). Fasting plasma total antioxidant status (ferric-reducing antioxidant power), ascorbic acid (AA), α-tocopherol (total and lipid standardized), malondialdehyde, total cholesterol, triacylglycerol, uric acid (UA), and high-sensitivity C-reactive protein (hsCRP) were measured.

Results

Plasma AA was significantly higher in the vegetarians than in the omnivores (90.5 ± 21.0 and 61.8 ± 17.0 μM; P < 0.001). The vegetarians had lower concentrations of triacylglycerol, UA, and hsCRP. Plasma total and lipid-standardized α-tocopherol concentrations were also lower in the vegetarians: 22.0 ± 5.9 and 27.0 ± 7.9 μM versus 3.76 ± 0.57 and 4.23 ± 0.58 μM per millimoles per liter of total cholesterol plus triacylglycerol, respectively. There was a significant inverse correlation between AA and UA (r = −0.343, P < 0.01; n = 60) and between AA and hsCRP (r = −0.306, P < 0.05; n = 55). Plasma ferric-reducing antioxidant power and malondialdehyde did not differ significantly between groups; however, the contribution of AA to the total antioxidant capacity of plasma was approximately 50% greater in the vegetarians.

Conclusions

A long-term vegetarian diet is associated with markedly higher fasting plasma AA concentrations and lower concentrations of TAG, UA, and hsCRP. Long-term vegetarians have a better antioxidant status and coronary heart disease risk profile than do apparently healthy omnivores. Plasma AA may act a useful marker of overall health status.

Introduction

Diets rich in fruit and vegetables protect against chronic, degenerative disease. These beneficial effects are believed to be due to plant-based antioxidant compounds, such as ascorbic acid, carotenoids, and flavonoids, that may protect key biological sites, such as lipoproteins, membranes, and DNA, from oxidative damage.1, 2 Evidence of benefit is so strong that the World Cancer Research Fund recommends five or more servings of fruit and vegetables each day,3 and the recommended daily intake of vitamin C in the United States was recently revised upward to 75 mg/d for women and 90 mg/d for men.4 Although the identity of the protective component or components in fruit and vegetables is not yet clear, evidence exists that intakes and plasma concentrations of vitamin C (ascorbic acid) correlate inversely with all-cause mortality rate and may act as biomarkers of health status.5 In addition, the lipophilic antioxidant vitamin E (mainly α-tocopherol) is an antiatherogenic and anti-inflammatory agent.6, 7 Increased antioxidant status, therefore, may account for at least part of the benefit of plant-based diets. One cross-sectional study has suggested that vegetarians are healthier than non-vegetarians,8 and we were interested in determining whether vegetarians exhibit a more favorable profile in terms of antioxidant status and risk of chronic disease than do omnivores of similar age. Therefore, we compared biomarkers of antioxidant status, oxidative stress, inflammation, and coronary heart disease (CHD) risk in a group of long-term vegetarians with those of age- and sex-matched omnivores.

Section snippets

Materials and methods

Thirty vegetarians (27 women and 3 men; mean age ± standard deviation: 44.2 ± 9.0 y) were recruited with their informed consent. These subjects had been vegetarian for 5 to 55 y (21.8 ± 12.2 y). They ate no meat or fish owing to their religious (Taoist) beliefs, but some occasionally consumed eggs and milk in small amounts. The control group comprised 30 non-Taoist adults (27 women and 3 men, 44.0 ± 9.2 y) matched by age- and sex-stratified sampling from a pool of participants in a

Results

As shown in Table I, plasma ascorbic acid concentrations were significantly higher in the vegetarians than in the omnivores (P < 0.0001). Malondialdehyde concentrations were slightly but non-significantly lower in the vegetarians. No significant difference in the total antioxidant capacity of plasma (as the FRAP value) was seen; however, the contribution of ascorbic acid to the FRAP value of the vegetarian subjects was 50% higher than that in the omnivores (averaging 16.6% and 11.8% for

Discussion

Individuals who eat a diet rich in fruit and vegetables or who have high plasma concentrations of antioxidant micronutrients have a low risk of cardiovascular disease and stroke.13, 14, 15, 16 This observational evidence has led to the recommendation that high-risk individuals or populations with a high incidence of CHD and stroke should substantially increase their intakes of dietary antioxidants. It has been shown that plasma concentrations of antioxidants, such as α- and β-carotenoids and

Acknowledgements

The authors thank the anonymous reviewers who provided valuable, constructive, and expert comment.

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  • Cited by (0)

    This study was funded by The Hong Kong Polytechnic University.

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