 By Elena Voropay You know that the antioxidant compounds we obtain from eating five to seven serves a day of fruit and vegetables can help protect us from heart disease and certain cancers. So, you think that eating all fruit and vegetables must be good for you. Think again - you may be doing your body more bad than good. Antioxidants are naturally occurring chemicals in foods that help to counter the detrimental effects of oxygen free radicals, which form during normal metabolism and through external factors such as x-rays, ultra-violet radiation and pollution. Most of the antioxidants we consume come from plants. They include vitamins A, C and E, carotenoids such as beta-carotene, some minerals, phenolic compounds and other naturally occurring chemicals with antioxidant properties.
The effectiveness of antioxidants suddenly became controversial after researchers found that consumption of some of these compounds may be linked to increased mortality. A meta-analysis of 68 randomized trials published in the Journal of the American Medical Association reported that vitamins A and E could increase mortality by up to 16 percent.
However, critics, including the nutritionists from the Agricultural Research Service, decided to do their own research. They assessed antioxidant capacity (AOC) of blueberries, grapes, kiwifruit, strawberry, cherry and dried plums through Oxygen Radical Absorbance Capacity (ORAC) test which tells how much of these mystery 'healthy' compounds are carried in certain foods.
Interestingly, despite the high antioxidant content of plums, the fruit did not in fact raise the AOC plasma levels in participants. This was attributed to the fact plums contain chlorogenic acid, a phytochemicals not easily absorbed by humans. The results for blueberries, which are lauded for their high antioxidant content, were somewhat more surprising - to get the benefits of these power foods you need to eat a lot of them since a single half-cup serving of the berries is not enough to elevate AOC levels. Consumption of grapes and kiwi boosted plasma AOC levels, but which compounds were responsible for this remains unknown.
For your note, just remember that if certain foods, or more specifically antioxidants, increase your plasma AOC, they not necessarily decrease your risk of chronic degenerative disease.
More research is needed to substantiate this further, and to establish the importance of non-nutrient antioxidants in the diet. At present it appears that the wide mix of antioxidants obtained from whole plant foods work more effectively in the body that single supplements with pure antioxidants in tablet form although these may be of value in some circumstances. Current research is evaluating the importance of lesser-known antioxidants in plant foods as anti-cancer agents. Levels of intake of the known nutrient antioxidants needed to protect cells against naturally occurring and induced damage to genes, and the associated risks of cancer, also need to be established. Source:
Prior, Ronald L. et al. "Plasma antioxidant capacity changes following a meal as a measure of the ability of a food to alter in vivo antioxidant status." Journal of the American College of Nutrition. Vol. 26, No. 2, 170-181 (2007). |
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