Short-term impact of a lactovegetarian diet on adrenocortical activity and adrenal androgens

The aim of this study was to determine whether definite diet changes affect adrenocortical activity and/or adrenal androgen metabolism. A controlled experimental diet study with four consecutive diet periods (repeated measure design) was carried out in six healthy adult volunteers. Four nearly isoenergetic diets, two normal (N) moderately protein-rich, one protein-rich (P), and one low protein lactovegetarian (L), were fed. At the end of each 5-day diet period a blood sample and two 24-h urine specimens were obtained from each subject. Plasma levels of dehydroepiandrosterone sulfate (DHEAS) were elevated with diet L (6.5 +/- 1.4 vs. 5.3 +/- 1.1 mumol/L; P < 0.05) compared to diet N, whereas other plasma hormones, including cortisol and insulin-like growth factor I did not vary markedly. A marked increase of 60% was seen in the urinary 24-h output of 3 alpha-androstanediol glucuronide with diet P. Urinary 24-h excretion rates for C peptide, free cortisol, DHEAS, and total 17-ketosteroid sulfates were clearly reduced with diet L compared to those with diet N or P. Our results show that a lactovegetarian diet can reduce adrenocortical activity (at least after a short term diet change). In addition, this vegetarian nutrition leads to a particular metabolic situation (elevated plasma DHEAS and reduced urinary DHEAS output) that usually is characteristic of fasting. Peripheral androgen metabolism as reflected by urinary 3 alpha-androstanediol glucuronide appears to be influenced only by high protein intake (diet P). Further research (controlled dietary long term investigation) is required 1) to validate whether the effects of diet on adrenocortical activity represent sustained endocrine changes and 2) to elucidate the underlying mechanism.