Endocrine Abstracts

The aim of this study was to determine if a change in the amount of fat consumed in the diet influenced female salivary postprandial testosterone and cortisol concentrations and whether any changes affected circadian rhythm.

The study was conducted on 9 healthy female subjects aged 21–45 years (BMI mean=22.5±1.61) and has been approved by the University College Ethical Committee. Over 3 non-consecutive days, each subject consumed 2 meals, lunch and evening dinner, containing either, high fat (40–45% of total energy), low fat (20–25% of total energy), or the subjects usual daily meals. Saliva samples were collected at 11 predetermined times during the challenge days. Testosterone and cortisol levels in each sample were measured by specific and sensitive ELISA methods following ether extraction of saliva samples. Paired t-tests and repeated measures ANOVA were used for statistical analyses.

On high fat diet, testosterone levels post lunch rose from a mean of 155 to 307 pg/ml.Testosterone results were significantly higher on the high fat diet compared to usual daily diet (p=0.018 at 30 minutes post-lunch, and p=0.006 at 1 hour post-lunch). Testosterone levels on low and high fat diets differed significantly 30 minutes post-lunch (p <0.05) and 5 minutes pre-dinner (p=0.03). There was a slight rise, though not significant, in testosterone level post dinner (From a mean of 136 to 189 pg/ml, p=0.22) on high fat content compared with a drop on low fat meal (from a mean of 212 pg/ml to 78 pg/ml). Cortisol levels on the low fat meal differed significantly from the high fat meal at1 hour and 2 hours post lunch (p<0.05 and p<0.01 respectively) and 2 hours post-dinner (p=0.041). Mean cortisol level on high fat meal rose from a mean of 3.34 to 4.935 ng/ml post lunch, with a smaller increase after evening meal (from 2.402 to 3.641 ng/ml). The findings of this study indicate that the amount of fat consumed in a meal, can influence postprandial levels of salivary testosterone and cortisol and their circadian rhythm profile. Such an effect on steroid hormones might have an impact on the person’s daily activities and general health and wellbeing.