Levels of Endogenous Sex Hormones in Male Vegetarians and Non-Vegetarians

Abstract

Background: Wholly plant-based diets have been reported to have many beneficial outcomes. In some studies, higher circulating levels of free androgens have been suggested to increase the risk of developing prostate cancer. Men are reported to have lower levels of the sex hormone-binding globulin which may increase in response to oestrogen and decrease in response to androgens. The vegetarian diet consisting of vegetables and legumes and particularly soy products, are rich in phytoestrogens, which compete with other oestrogens for receptor binding. For the male vegetarian, increased serum concentration of oestrogens may influence the levels of testosterone and sex hormone-binding globulin. A study to examine the levels of endogenous sex hormones in vegetarian and non-vegetarian male has not yet been conducted in Ghana. Aim: The aim of the study was to examine the levels of endogenous sex hormones in vegetarian and non-vegetarian males. Methods: This was a case-control study of 52 healthy males (22 vegetarians and 30 nonvegetarians) recruited from four locations in the Greater-Accra Region. A structured questionnaire was used to obtain background and anthropometric data of all participants. Current and usual dietary intake was assessed using a 24-hour recall and a modified food frequency questionnaire respectively. Blood samples were collected after an overnight fast and serum hormone levels assessed by radioimmunoassay. Results: Vegetarians were relatively older than non-vegetarians. The mean age of the participants was 49.4 ± 12.7 years. Motivation for choosing the dietary lifestyle was more religious than health inclined. Half of the vegetarians were lacto-ovo vegetarians. All the participants were non-smokers, with alcohol consumption of one or two standard drink servings in 57% (n=17) of non-vegetarians. Vegetarians weighed less than nonvegetarians but BMI was insignificantly different. Mean diastolic blood pressure was significantly lower (p=0.025) in vegetarians (77.1 mmHg) than non-vegetarians (84.4 mmHg). There were significant differences in mean intake of protein (p=0.001), calcium (p=0.003), iron (p=0.001) and zinc (p=0.043). With the exception of calcium, mean intakes of the above mentioned micronutrients were all lower in vegetarians. The mean serum testosterone levels of vegetarians (20.0 nmol/L) was significantly lower (p=0.022) than in non-vegetarians (24.6 nmol/L) but mean serum oestradiol levels was significantly higher (p=0.037) in vegetarians (339 pmol/L) than in non-vegetarians (279 pmol/L). Significant differences (p=0.001) were found comparing age and type of protein (animal vs. plant) consumed with hormone levels. Besides oestradiol in non-vegetarians, there were inverse but insignificant associations in age and type of protein consumed with hormone levels. Mean serum oestradiol of non-vegetarians who did not consume soy compared to mean protein intake was directly associated although insignificant. Conclusion: There were significant differences in mean weight, diastolic blood pressure and visceral fat of vegetarians and non-vegetarians but mean BMI, systolic blood pressures and body fat were not significantly different. Mean serum testosterone was significantly lower in vegetarians but mean serum oestradiol was significantly higher in vegetarians. No significant associations were found between types of protein frequently consumed and endogenous levels of serum sex hormones testosterone and oestradiol.