A review of the epidemiological evidence for the ‘antioxidant hypothesis’

Abstract

Objective: The British Nutrition Foundation was recently commissioned by the Food Standards Agency to conduct a review of the government's research programme on Antioxidants in Food. Part of this work involved an independent review of the scientific literature on the role of antioxidants in chronic disease prevention, which is presented in this paper. Background: There is consistent evidence that diets rich in fruit and vegetables and other plant foods are associated with moderately lower overall mortality rates and lower death rates from cardiovascular disease and some types of cancer. The 'antioxidant hypothesis' proposes that vitamin C, vitamin E, carotenoids and other antioxidant nutrients afford protection against chronic diseases by decreasing oxidative damage. Results: Although scientific rationale and observational studies have been convincing, randomised primary and secondary intervention trials have failed to show any consistent benefit from the use of antioxidant supplements on cardiovascular disease or cancer risk, with some trials even suggesting possible harm in certain subgroups. These trials have usually involved the administration of single antioxidant nutrients given at relatively high doses. The results of trials investigating the effect of a balanced combination of antioxidants at levels achievable by diet are awaited. Conclusion: The suggestion that antioxidant supplements can prevent chronic diseases has not been proved or consistently supported by the findings of published intervention trials. Further evidence regarding the efficacy, safety and appropriate dosage of antioxidants in relation to chronic disease is needed. The most prudent public health advice remains to increase the consumption of plant foods, as such dietary patterns are associated with reduced risk of chronic disease.

Nutritional quality of fresh and heated Aleppo pine (Pinus halepensis Mill.) seed oil: trans-fatty acid isomers profiles and antioxidant properties

“…Free radical scavenging capacity is usually measured with the aim of determining possible biological activities of a sample rich in antioxidants since the latter have been related to the prevention of several diseases (Stanner et al 2004). The DPPH assay measures the ability of the antioxidants present in the sample to scavenge free radicals.…”

Fontes vegetais naturais de antioxidantes

“…Há muita controvérsia nessa área de pesquisa, indicando a necessidade de obtenção de evidências inequívocas a respeito da eficácia, segurança e dosagem apropriada de antioxidantes em relação a doenças crônicas. 19 Assim, apesar de não haver comprovação científica definitiva, é prudente e aconselhável, em termos de saúde pública, aumentar o consumo de alimentos vegetais 19 e seguir uma dieta similar à denominada "dieta do Mediterrâneo". 20 Um dos principais aspectos relacionados ao efeito protetor desses alimentos tem sido atribuído, em parte, à presença de compostos antioxidantes, dentre os quais se destacam os compostos fenólicos, além dos bem conhecidos β-caroteno, vitamina C e vitamina E. [21][22][23] O termo antioxidante tem natureza multiconceitual.…”

Reduction in hypercholesterolemia and risk of cardiovascular diseases by mixtures of plant food extract: a study on plasma lipid profile, oxidative stress and testosterone in rats

“…polyphenols (kris-Etherton et al, 2002;Pellegrini et al, 2003;Stanner et al, 2004;Guo and xu, 2005). The present study was postulated to prepare two plant food extract mixtures.…”