| Abstract: | Trace elements are scarce in our body, where as some of them are implicated in various metabolic processes. Regular exercise alters the levels and increases outputs and requirements of some of them. Zinc losses through sweat, urine and feces are increased in response to chronic and acute exercise. Chromium losses, mainly via the urinary tract, increase following training and simple carbohydrate intake, a common situation among sportsmen. Copper losses increase in sweat. Recommended daily allowances are not always satisfied, depending upon the trace element being considered. Zinc and chromium intakes are often marginal, while copper does not seem to be present in sufficient amounts in a high percentage of athletes. It is not the same for manganese, always delivered in sufficient amounts. Selenium intake mainly depends on its rate in the soil, this factor varying the most from one country (and one average diet) to another. So precise recommendations such as three servings of meat per week seem to be justified. Some diets are not adequate towards some trace element intakes, and this abnormality enhances the probability that deficiencies appear. Complex interrelationships enhance or impede supplementation. For instance, copper, zinc and iron inhibit each other's absorption at gut's level. These interrelationships make nutritional strategy harder to implement. Some trace elements (selenium, zinc, copper or manganese — the latter at the mitochondrion level) act as free radical scavengers. Thus increased intakes at appropriate levels may be required. Changes in dietary habits, improving “nutritional density” is one possible strategy. But for some elements, the required amounts are not currently available in our diet. Thus supplementation becomes necessary in some cases. As far as vanadium and silicon are concerned, and though they are implicated in some physiological processes linked to sports, it is not possible to recommend at present precise amounts, even though future research will certainly show that their intake is to be increased. |
