Loss of Trace Elements not a Concern in Well-Hydrated Athletes

If you are a hard-training athlete you need more than "trace amounts" of trace elements, don't you? No, actually not. You may be somewhat disappointed now, but the expensive trace element supplement you just ordered might turn out to be a complete waste of money - at least, this is what the results of a recently published study by Carlos González-Haro et al. (González-Haro. 2010) suggest.

Figure 1: Changes in plasma trace element levels (Zn, Mn, Se and Co) for the different relative exercise intensities studied and the 7 min recovery period.

As figure 1 (above) shows, lactate concentrations constantly increased in the course of the 7 minutes after a cycloergometer test, where, after a warm-up of 10 min at 2.0 W kg⁻¹, workload had been increased by 0.5 W kg⁻¹ every 10 min until exhaustion. The trace mineral concentration, on the other hand, remained stable over the whole study period (exercise + recovery). This observation led the scientists to conclude ...

[...] in euhydrated well-trained endurance athletes no effects on plasma levels of Zn, Se, Mn and Co were observed either during medium duration exercise, at a full range of intensities (41–92%VO_2peak), or during a seven-minute recovery period. These subjects showed no deficiency in Zn or Se and probably were not deficient in Mn or Co either (though cutoff levels are not known).

So, if you have not opened your "high quality trace element" supplement yet, make use of your 14-days conversion right ;-)

Non-Negligable Loss of Minerals & Trace Elements With Sweat in Healthy Boxers

Turkish scientists (Saraymen. 2010) analyzed the sweat of 21 male cross-country boxers and found only a minor loss of trace elements copper, zinc and iron. As my plot of the study results as percentages of the recommended daily allowances (RDA) shows, the loss in magnesium, as well as the chromium are much more pronounced:

Figure 1: Loss of minerals and trace elements in 1L of sweat expressed as percentages of the RDA

Other than magnesium which is one of the commonest dietary supplements and is consumed in more than adequate amounts by most physically active adults (Hickson. 1986, 1987, 1986; Worme. 1990), studies suggest that chromium intake is rather on the lower end of the range:

Recent analyses of self-selected diets in the United States indicate that nutritionally balanced diets contain variable amounts of chromium ranging from 1.2–1.4 ng Cr/MJ (5–6 µg/1000 kcal) (8) to 3.6 ng Cr/MJ (57) based on the foods consumed. Other reported daily intakes of chromium in diets include 29 µg in Finland, 56 µg in Canada, 25 µg in England, and 37 and 28 µg in the United States. (8). Data on the chromium intakes of physically active persons per se are not available. Nielsen proposed that because overt signs of chromium deficiency are not present at a chromium intake of 50 µg/d, this amount may be adequate to ensure good health in most individuals (8). (Lukaski. 2000)

In spite of that, an increase in exercise performance via chromium supplementation has not yet been established and chromium deficiency is something that is practically non-existent. Furthermore, most multi-vitamins/-minerals do contain more than adequate amounts of chromium to keep you at a healthy level. Excessive consumption of additional chromium should thus be avoided, because a) it has been linked to chromosome damage (Stearns. 1995) and b) its positive effect on insulin signaling and diabetes is debatable and by no means thoroughly investigated.