Nutrition Supps Uncategorized

Do antioxidant supps cause more harm than good?

Aaron Deere is a sports nutritionist, functional medicine consultant and advanced personal trainer. He is based in London.

One of the main reasons governments and health authorities around the world spend millions promoting the idea of eating a certain number of servings of fruit and vegetables each day is because they are full of antioxidants. An antioxidant is a molecule that prevents oxidation, a chemical reaction that results in the production of free radicals, which begin a chain reaction that can damage or destroy cells.

While oxidation reactions are an essential part of any organism’s life cycle, too much too often can be highly damaging, increasing the risk of certain forms of cancer and cardiovascular disease. Diets rich in fruit and veg have been shown to correlate with reduced risks of these diseases, with early epidemiological studies identifying beta-carotene, ascorbic acid and the tocopherols (which act like vitamin E) as some of the most potent and protective antioxidants[1].

This is why antioxidants have been marketed as the elixir of life, because they help neutralise the damage caused by free radicals. The logic follows that if antioxidants mitigate the damaging effect of free radicals, then supplementing them can potentially prevent a host of serious health implications, right? Not so fast.

Defense mechanisms
Free radicals perform essential functions within your cells as important signalling molecules.
Introducing pharmacological amounts of exogenous antioxidants can consequently interfere with defence mechanisms, such as phagocytosis (an immune system response where a cell consumes a particle, such as bacteria), apoptosis (programmed cell death), and detoxification (the removal of a toxic substance)[2].

As a result, more stable radicals are formed, which can move deeper into lipoproteins or cells and potentially cause damage to the lipids or DNA[3]. They may also increase cell proliferation, along with mutations because of DNA damage, which can result in the formation of cancerous cells[4].

Intervention studies originally set out to ratify the findings of the epidemiologic studies, but actually found potential adverse effects from antioxidants given in supplemental form, through a pro-oxidant effect which leads to an increase in cancers, heart disease and morbidity[5].

One study reported that subjects who received beta-carotene supplementation actually developed a higher incidence of lung cancer, and vitamin E supplementation at a dosage >150 IU per day resulted in an increase of all-cause mortality, with the risk of mortality progressively increasing up to doses ≥ 400 IU per day[6].

Balanced diet
Therefore, if you consistently eat a balanced diet, there is unlikely a need for supplementing  antioxidants. Ongoing consumption of pharmacological doses of antioxidants has directly been shown to increase probability of early morbidity, so the average ‘health conscious’ multi-vitamin consumer is doing more long-term harm than good. As with almost every aspect of training, nutrition and supplementation, there is no one-single simple solution to guarantee optimal health. It is always far better to eat a variety of fruit and vegetables every day and you’ll give your body all it needs to keep your firing on all fronts.

1 Frei B (1994) Reactive oxygen species and antioxidant vitamins: mechanisms of action. The American Journal of Medicine. 97(3A), 5S-13S.
2 Bjelakovic G, Nikolova D, Gluud L, Simonetti R, Gluud C, (2007) Mortality in Randomized Trials of Antioxidant Supplements for Primary and Secondary Prevention Systematic Review and Meta-analysis, The Journal of the American Medical Association, 297(8), 842-857.
3 Bender D (2008). Nutrition and Metabolism. 4th ed. USA: CRC Press. 192.
4 Gonzalez M, Riordan H, Miranda-Massari J (2002) Vitamin C and Oxidative DNA Damage Revisited. Journal of Orthomolecular Medicine, 17(4), 225-228.
5 Rietjens I, Boersma M, de Haan L, Spenkelink B, Awad H, Cnubben N, van Zanden J, van der Woude H, Alink G & Koeman J (2002) The pro-oxidant chemistry of the natural antioxidants vitamin C, vitamin E, carotenoids and flavonoids, Environmental Toxicology and Pharmacology, 11, 321–333.
6 Miller E, Barriuso P, Dalal R, Riemersma D & Rudolph A; (2007) Meta-Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality, Annals of Internal Medicine, 142(1), 37.



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