ABSTRACT
Oxidative Stress ........................................................................................................268 12.4.2 The Mediterranean Diet and Erectile Function ........................................................268 12.4.3 Alcohol Consumption and Erectile Function ........................................................... 270
12.5 Effects of Weight Loss on Testosterone and Erectile Function in Obese Men .................... 270 12.6 Improvement in Risk Factors for Low Testosterone and ED by Diet-Induced
Weight Loss ..................................................................................................................... 271 12.6.1 Effects of Macronutrient Composition on Reduction in Weight and Adiposity ....... 271 12.6.2 Improvements in Inammation and Endothelial Dysfunction with Diet-Induced
Weight Loss .............................................................................................................. 272 12.6.3 Improvement in Lower Urinary Tract Symptoms, Libido, and Quality of Life
with Diet-Induced Weight Loss ................................................................................ 272 12.7 Evidence for Dietary Antioxidants in Improvement of ED .................................................. 273 12.8 Low Testosterone and Sexual Dysfunction in Underweight and Anorexic Men .................. 275 12.9 Key Points Summary ............................................................................................................ 276 References ...................................................................................................................................... 277
Testosterone production in men is regulated by the hypothalamic-pituitary-testicular axis. Pulsatile hypothalamic secretion of gonadotropin-releasing hormone (GnRH) leads to release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary, which stimulate testosterone production by Leydig cells in the testis [1]. Sex hormone-binding globulin (SHBG), as the main carrier protein of testosterone in the circulation, is a major determinant of total testosterone level, and is reduced in obese insulin-resistant states [2]. In adipose tissue, testosterone is converted to estradiol by the enzyme aromatase, leading to reduced circulating testosterone. Obesity, characterized by excessive accumulation of adipose tissue, is dened by the World Health Organization as body mass index (BMI) exceeding 30 kg/m2 (though ethnic-specic cutoffs vary according to cardiovascular risk) [3]. Abdominal obesity, dened by increased waist circumference (WC), also has ethnic and sex-specic thresholds [3].
