Antioxidants intervention studies

Loft, S. and Poulsen, H.E., Antioxidant intervention studies related to DNA damage, DNA repair and gene expression. Free Radic. Res., 33 Suppl., S67, 2000. 

See also Antioxidants Intervention Studies. Ascorbic Acid Physiology, Dietary Sources and Requirements. Vitamin A Biochemistry and Physiological Role. Vitamin E Metabolism and Requirements. 

Many epidemiological studies have analyzed the correlations between different carotenoids and the various forms of cancer and a lot of conclusions converge toward protective effects of carotenoids. Many studies were carried out with (i-carotene. The SUVIMAX study, a primary intervention trial of the health effects of antioxidant vitamins and minerals, revealed that a supplementation of p-carotene (6 mg/day) was inversely correlated with total cancer risk. Intervention studies investigating the association between carotenoids and different types of cancers and cardiovascular diseases are reported in Table 3.1.2 and Table 3.1.3. 

Experimental evidence in humans is based upon intervention studies with diets enriched in carotenoids or carotenoid-contaiifing foods. Oxidative stress biomarkers are measured in plasma or urine. The inhibition of low density lipoprotein (LDL) oxidation has been posmlated as one mechanism by which antioxidants may prevent the development of atherosclerosis. Since carotenoids are transported mainly via LDL in blood, testing the susceptibility of carotenoid-loaded LDL to oxidation is a common method of evaluating the antioxidant activities of carotenoids in vivo. This type of smdy is more precisely of the ex vivo type because LDLs are extracted from plasma in order to be tested in vitro for oxidative sensitivity after the subjects are given a special diet. 

In summary, the evidence for the preventive effect of flavonols in cardiovascular disease is growing based on mechanistic, animal, epidemiological, and short-term intervention studies. However, we must learn from the lessons with dietary antioxidants, the last word awaits large-scale intervention clinical trials. 

R22. Rosell, M., Regnstrom, J., Kallner, A., and Hellenius, M. L., Serum urate determines antioxidant capacity in middle-aged men—A controlled, randomized diet and exercise intervention study. 

A large number of studies use comparison of people before and after, say e.g. antioxidant intervention. Such a design is considered based on historical controls and should not be performed. 

An eight week randomized placebo-controlled intervention study reported on the antioxidant status of lead factoiy workers drinking traditional/fermented rooibos (76). The modulation of oxidative status of these workers was shown by a decreased level of lipid peroxidation (measured as malondialdehyde in the plasma) and increased level of blood glutathione (GSH). The authors suggested that rooibos could play a beneficial preventive role in occupationally exposed... 

Rietveld and Wiseman" summarized the available evidence of antioxidant effects of tea from human clinical trials. The authors concluded that tea flavonoids are potent antioxidants that are adsorbed from the gut after consumption. They showed that human intervention studies with green tea and black tea demonstrated a significant increase in plasma antioxidant capacity in humans about 1 h after consumption of a... 

Milbury, P. and Blumberg, J.B., Dietary antioxidants human studies overview, in Oxidative Stress and Aging Advances in Basic Science, Diagnostics, and Intervention, Rodriguez, H. and Cutler, R.G., Eds., World Scientific Publishing Co., 2003, pp. 487-502. 

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