Sunday, November 9, 2008

Antioxidants - A Risk Benefit Profile

Antioxidants are all the rage these days. Paradoxically, while there are many in vitro studies demonstrating potential benefits from antioxidants, and many studies indicating their utility in various pathologies, there is scant evidence that antioxidant supplementation prolongs life.

I have concerns about the absorbing huge doses of antioxidants. Oxidation is an intrinsic and vital physiological process, filling up your body with antioxidants may sound like a good idea but how often have we been subjected to the latest nutrition craze only to find that it was nonsense? Far too many times, there needs to be much caution in the use of antioxidants. This recent study highlights that while antioxidants have considerable therapeutic promise, indiscriminate use of antioxidants can also lead to pathological processes.

One thing not mentioned in this study but is very important is the use of alpha tocopherol, typically and misleading referred to as Vitamin E. There are in fact a number of types of vitamin E and high consumption of alpha tocopherol can reduce the concentrations of gamma tocopherol and delta tocopherol, both of which are better variants than alpha tocopherol. . This may explain why some studies have found that high dosages of alpha tocopherol can increase mortality. The reason why most vitamin E supplements only contain alpha tocopherol is simple: it is the cheapest to manufacture. If you want a good source of vitamin E use wheatgerm. Note what the below study found in relation to wheatgerm:

Intriguingly, the combined treatment with wheat germ and vitamin C profoundly inhibited metastasis formation in various tumor models of different origin (Lewis lung carcinoma, B16 melanoma and human colon carcinoma xenografts [HCR25]) [61]. On the contrary, wheat germ had no toxicity on peripheral blood leukocytes (PBLs) at doses that affected tumor cells. The crude powder extract of fermented wheat germ inhibits nucleic acid ribose synthesis primarily through the non-oxidative steps of the pentose cycle [60]. Curiously, another quinone compound, carnosic acid quinone, like wheat germ, recovers potent antioxidant activity upon standing [62].

Note that last sentence, that the antioxidants in wheat germ "recover" their antioxidant activity. Now whether or not this happens in the body is another question but given that wheat germ is cheap and a valuable nutrient source why bother with all those expensive supplements?

This study also highlights that certain antioxidants, at high doses, can actually induce oxidation. Ever since that now famous study on beta carotene which found it increased the rate of lung cancer in smokers(as if that were possible!) I have harbored suspicions that beta carotene should not be added to multi vitamins. Smokers should definitely avoid beta carotene in vitamin pills and problem be careful about the intake from natural sources. As for non smokers, the data is equivocal. Beta carotene does not appear to be a causative factor for or against developing cancer.

Ascorbic acid, a variant of vitamin C, appears to be a double edged sword. At high doses it can stimulate the production reactive oxygen species, particularly in the presence of free iron, the latter often being present in inflammatory conditions. Mega dosing of vitamin C is a waste of money and can damage the gut. Once tissue saturation of vitamin C is achieved there is little point in swallowing vitamin C tablets because it will not pass the gut wall. Smokers should increase their intake of vitamin C has it has been shown to help preserve vitamin E levels. As with most antioxidants, it is generally better to consume these throughout the day because this will help maintain tissue levels through the course of the day, whereas consuming antioxidant rich foods or supplements at one time of the day will lead to depletion until topping up occurs at the next meal.

The flip side of megadosing for vitamin C is recent studies which found that intravenous injections of vitamin C may have therapeutic use in treating some cancers.

The below study can be downloaded at this site.

The role of antioxidant supplement in immune system, neoplastic,
and neurodegenerative disorders: a point of view for an assessment
of the risk/benefit profile
Daria Brambilla1, Cesare Mancuso2, Mariagrazia Rita Scuderi1, Paolo Bosco3,
Giuseppina Cantarella1, Laurence Lempereur1, Giulia Di BenedettoLL0000001,
Salvatore Pezzino1 and Renato Bernardini*1
Nutrition Journal 2008, 7:29 doi:10.1186/1475-2891-7-29
Date obtained
Date Read
Date to Review
Web Page
This review will discuss some issues related to the risk/benefit profile of the use of dietary antioxidants. Thus, recent progress regarding the potential benefit of dietary antioxidants in the treatment of chronic diseases with a special focus on immune system and neurodegenerative disorders will be discussed here. It is well established that reactive oxygen species (ROS) play an important role in the etiology of numerous diseases, such as atherosclerosis, diabetes and cancer. Among the physiological defense system of the cell, the relevance of antioxidant molecules, such as glutathione and vitamins is quite well established. Recently, the interest of researchers has, for example, been conveyed on antioxidant enzyme systems, such as the heme oxygenase/biliverdin reductase system, which appears modulated by dietary antioxidant molecules, including polyphenols and beta-carotene. These systems possibly counteract oxidative damage very efficiently and finally modulate the activity of oxidative phenomena occurring, for instance, during pathophysiological processes. Although evidence shows that antioxidant treatment results in cytoprotection, the potential clinical benefit deriving from both nutritional and supplemental antioxidants is still under wide debate. In this line, the inappropriate assumption of some lipophylic vitamins has been associated with increased incidence of cancer rather than with beneficial effects.

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