Effect of a herbal yeast food supplement and long-distance running on immunological parameters.

The effect of a food supplement on immunological parameters of 16 long-distance runners was tested in a randomized, double-blind and placebo-controlled trial. The supplement comprised plasmolysed herbal yeast, malt, honey, and orange juice. No statistically significant differences between the two groups regarding the following variables were detected at three sessions at rest and immediately after a 21 km run: total and differential white blood cell counts, numbers of B- and T-cells and T-subpopulations, concanavalin-A-induced lymphocyte proliferation, serum levels of immunoglobulins, neopterin, IL-2 receptors, beta 2-microglobulin, complement factor b, c4 and c3c, and c1-inactivator. These findings suggest that the effects of the tested food supplement on these parameters are negligible with respect to improvements in the immunological status of long-distance runners. The changes observed immediately after the run had a transient character. In both groups, however, low lymphocyte counts, IgG subclass 2 levels and c1-inactivator levels were noted at rest, which indicate that the immune status of endurance athletes may be affected by training.