The onset of puberty is changing in western countries. Puberty is the activation of the reproductive system, and is initiated by a complex series of events that are not fully understood. BMI has been linked to the advancement of puberty, but is unlikely to be the whole story as girls with a normal BMI are also advancing through puberty earlier. It is well known that western diets are high in calories, but the high salt content in these diets has been overlooked as a potential contributing factor. Salt consumption in the US and Europe far exceeds the recommended daily values. We hypothesize that salt intake may affect the timing of puberty. Our study on Sprague Dawley rats fed a high salt (8%) diet from weaning (Day 21) have a significant delay in the onset of puberty compared to a control, 0.3% salt, diet. Corticosterone levels were not different between control and high salt-fed rats, suggesting that the pubertal delay was not mediated by stress. FGF-21, which has been implicated in puberty onset, also did not differ between high salt and control rats. Salt intake was then varied to determine if lower salt intake may be stimulatory to puberty. Rats were fed no salt (0.01%), control (0.3%), 2%, or 4% salt. Rats fed no salt showed significantly delayed puberty. Our data showed a trend for 2% salt to cause a slight advancement in puberty, whereas 4% salt was not significantly different from control. To establish optimal salt-intake, rats were given the option of drinking saline (0.5% salt) or pure water while being fed no salt, 0.3%, or 2% salt in their chow. Rats fed no salt consumed 3.6±0.8 mg/g rat per day salt compared to total food intake. Control rats consumed 2.9±0.9 mg/g rat per day salt, and 2% salt fed rats consumed 5.1±0.5 mg/g rat per day total salt. This data suggests that our 2 and 4% high salt diets are within the physiological ranges of salt consumption in rats. Our data shows that high salt can delay puberty at the highest levels, but may advance puberty at lower levels. Current salt loading in western populations has the potential to effect reproductive health, and warrants further attention.
16 - 20 May 2015
European Society of Endocrinology