By antioxidants we mean all those molecules whose function is to prevent the interaction of highly reactive oxygen atoms (the well-known free radicals) with the body’s cell membranes, protecting the latter from the aggression of the former. However, they also possess a function that facilitates recovery.

Function

  A study by Thompson (2001) highlights the ability possessed by antioxidants, and especially vitamin C, to reduce muscle soreness that sometimes occurs after the application of certain types of load (the most typical of which is bodybuildingtraining) and due to the accumulation of calcium in the extracellular environment (for more details, see the section on carnitine). This, however, is valid for female athletes, but not so for men (Bloomer, 2004; Shafat, 2004).

Negative notes

  Usually, whenever one starts the exogenous administration of any substance that the organism is capable of producing itself, it decreases or ceases its endogenous production altogether. Quite simply, this is a kind of ‘habit’ of external intake from which passive waiting follows. This also applies to antioxidants, therefore, an abuse of these substances can lead the body to develop dependence on exogenous introduction to satisfy its needs. Furthermore, Childs (2001) has proven that an intake of antioxidants in excess of one’s actual needs can paradoxically have a pro-oxidant effect. For these reasons, it is recommended to avoid the abuse of vitamin C supplements or other substances with an antioxidant function. These can and should only be taken where there is a real need for them (an example could be the endurance athlete, whose cells, as mentioned, are more exposed to the risk of oxidative damage).

Form and posology

  Antioxidant supplements are mainly available on the market in tablet form. In terms of dosage, vitamins have a very low level of toxicity and it is impossible to take a toxic amount through food. With supplementation this risk becomes more concrete, but only if the products are greatly abused. The best known antioxidant substances are vitamin C, vitamin A, carotenoids, vitamin E and polyphenols such as resveratrol. With regard to vitamin C, an intake of 60mg/day (including vitamin from food sources) is recommended, with the recommendation not to exceed 10g/day. With regard to vitamin A, not only the final molecules of retinol taken in through food and supplementation, but also the precursors must be taken into account when calculating intake levels. For this reason, recommended intake levels are expressed either in a unit of measurement called retinol equivalent (RE) or in another, called the international unit (IU). Below is the value of each:

• 1 RE = 1 mg (microgram) of retinol = 6 mg of β-carotene = 12 mg other carotenes = 3.33 IU

An intake of 700RE/day for men and 600RE/day for women is recommended. Doses of retinol in excess of 6mg/day are considered toxic. In addition to carotenoids with provitamin activity, i.e. the precursors of vitamin A, there are others with antioxidant activity. Examples are lycopene, zeaxanthin and lutein. Lycopene doses of up to 75mg/day are considered safe; a daily intake of 10-12mg of zeaxanthin and lutein is recommended. As for vitamin E, recommended intake levels are expressed, as for vitamin A, differentiating by molecule. The units of measurement are the tocopherol equivalent and the international unit:

• 1 Tocopherol Equivalent = 1mg RRR-tocopherol = 1.5 IU = 2mg β-tocopherol (beta tocopherol) = 3mg γ-tocopherol (gamma tocopherol) = 10mg

Since the main function of tocopherols is precisely that of antioxidant, and since the cell membranes under attack from free radicals are made up of polyunsaturated fatty acids, the tocopherol equivalents to be taken should be determined according to the polyunsaturated fats whose intake is planned in the diet. More specifically, the following are recommended:

Only intake levels above 2000mg/day are considered toxic (i.e. associated with intestinal damage). Finally, as far as polyphenols are concerned, there are no recommendations on intake quantities, so it is recommended to follow the indications on the label of the product purchased.