Is vitamin D status reflected by testosterone concentration in elite athletes?

Abstract

Vitamin D is a nutrient whose active form affects tissues as a hormone and possibly enhances performance. One plausible mechanism is by increasing testosterone concentration, which is established as an important factor for athletic performance. Therefore the aim of the study was to examine the relationship between plasma concentration of 25(OH)D and testosterone in Polish elite track and field athletes depending on vitamin D status, season, training period, body composition, sex, type of training, sun exposure and vitamin D supplementation. Plasma concentrations of 25(OH)D and testosterone were measured in all seasons within two years in athletes (70 females, 79 males) who represent strength (n = 103) and endurance (n = 46) kinds of sports, in the preparatorycompetitive season and transition period. There were no differences in 25(OH)D concentration between male and female athletes, insufficiency [25(OH)D < 30 ng/ml] was observed in 32.9%, whereas deficiency [25(OH)D < 20 ng/ ml] in 3.2%. Circannual rhythm was noted for vitamin D but not for testosterone concentration; no correlations between them were found either in strength or endurance athletes or between 25(OH)D and body composition. Testosterone concentration was higher in the transition period than in the preparatory-competition period only in male athletes. Higher 25(OH)D was observed in athletes who trained during winter in Africa (higher sun exposure) or used oral supplementation, whereas the respective testosterone levels were unchanged. In athletes, testosterone concentration did not reflect vitamin D status. The widespread of inadequate vitamin D status among athletes, makes it vital to recommend them the regular monitoring of 25(OH)D concentration and use of reasonable supplementation.

Keywords: Athletes; Exercise; Seasonal rhythm; Testosterone; Vitamin D status.

FIG. 1

Seasonal pattern of 25(OH)D concentration in blood in all athletes; * p < 0.05, ** p < 0.01, *** p < 0.001.

FIG. 2

Seasonal pattern of testosterone concentration in blood in female and male athletes.

FIG. 3

Blood concentration of 25(OH)D and testosterone during the training and competition months Dec-Aug (preparatorycompetitive period) and recovery months Sep-Nov (transition period) in male and female athletes; * p < 0.05, ** p < 0.01.

FIG. 4

Blood concentration of 25(OH)D and testosterone in female and male athletes who trained during winter in Poland (0), after the sun exposure in winter (Sun) and oral supplementation (Supl); ** p < 0.01, *** p < 0.001.

FIG. 5

Correlations between 25(OH)D and testosterone for the whole year in female and male athletes in all subjects (top) and in athletes with inadequate vitamin D status [25(OH)D below 30 ng/ml] separately (bottom).