The aim of this study was to determine if a change in protein/carbohydrate ratio influences plasma steroid hormone concentrations. There is little information about the effects of specific dietary components on steroid hormone metabolism in humans. Testosterone concentrations in seven normal men were consistently higher after ten days on a high carbohydrate diet (468 +/- 34 ng/dl, mean +/- .) than during a high protein diet (371 +/- 23 ng/dl, p less than ) and were accompanied by parallel changes in sex hormone binding globulin ( +/- nmol/l vs. +/- nmol/l respectively, p less than ). By contrast, cortisol concentrations were consistently lower during the high carbohydrate diet than during the high protein diet ( +/- micrograms/dl vs. +/- micrograms/dl respectively, p less than ), and there were parallel changes in corticosteroid binding globulin concentrations (635 +/- 60 nmol/l vs. 754 +/- 31 nmol/l respectively, p less than ). The diets were equal in total calories and fat. These consistent and reciprocal changes suggest that the ratio of protein to carbohydrate in the human diet is an important regulatory factor for steroid hormone plasma levels and for liver-derived hormone binding proteins.
If testosterone deficiency occurs during foetal development, then masculinisation of the foetus will fail to occur normally and this may give rise to disorders of sex development. If testosterone deficiency occurs during puberty, a boy’s growth may slow and no growth spurt will be seen. The child may also fail to develop full sexual characteristics (hypogonadism) associated with men undergoing puberty, including development of pubic hair, growth of the penis and testes and deepening of the voice. Around the time of puberty, boys with too little testosterone may also have less than normal strength and endurance, and their arms and legs may continue to grow out of proportion with the rest of their body.