Abstract and Introduction
Coffee intake is suggested to have a positive impact on chronic diseases, yet its role in urological diseases such as erectile dysfunction (ED) remains unclear. We investigated the association of coffee intake with incidence of ED by conducting the Health Professionals Follow-Up Study, a prospective analysis of 21,403 men aged 40–75 years old. Total, regular, and decaffeinated coffee intakes were self-reported on food frequency questionnaires. ED was assessed by mean values of questionnaires in 2000, 2004 and 2008. Multivariable adjusted Cox proportional hazards models were used to compute hazard ratios for patients with incident ED (n = 7,298). No significant differences were identified for patients with incident ED after comparing highest (≥4 cups/day) with lowest (0 cups/day) categories of total (hazard ratio (HR) = 1.00, 95% confidence interval (CI): 0.90, 1.11) and regular coffee intakes (HR = 1.00, 95% CI: 0.89, 1.13). When comparing the highest category with lowest category of decaffeinated coffee intake, we found a 37% increased risk of ED (HR = 1.37, 95% CI: 1.08, 1.73), with a significant trend (P trend = 0.02). Stratified analyses also showed an association among current smokers (P trend = 0.005). Overall, long-term coffee intake was not associated with risk of ED in a prospective cohort study.
Coffee is a rich source of caffeine, antioxidants and anti-inflammatory compounds,[1–4] and has been implicated to have a potentially beneficial role against chronic diseases. Yet, the role of coffee intake in urological diseases, specifically in erectile dysfunction (ED), remains undetermined.[5–9] The prevalence of ED in American men aged 20 years or older is 18.4%, which suggests that more than 18 million people are affected.[10,11] Further, in a prospective study, 17.7% of men (aged 40–75 years) reported incident ED during a 14-year follow-up. Among older men, these numbers substantially increase, which affects overall quality of life.[11,13,14]
An inverse association between coffee intake and improved erectile function is biologically plausible. In addition to being a major source of polyphenols, coffee has the potential to increase testosterone levels,[15–17] initiate a series of pharmacologic reactions that lead to the relaxation of the cavernous smooth muscle, and improve blood supply through penile arteries. In a previous cross-sectional analysis using the National Health and Nutrition and Examination Survey from 2001–2004, a nationally representative sample of the US noninstitutionalized male population, the equivalent of 2–3 cups of coffee per day was associated with a lower likelihood of ED. A further investigation of this association was conducted among men with comorbidities such as obesity, hypertension and diabetes, which are strong risk factors for ED. The findings remained the same among obese and hypertensive men, but not among men with diabetes.
Given the inherent limitations of the cross-sectional study design and a relatively small total sample size (n = 3,724) in the National Health and Nutrition and Examination Survey analyses, we decided to investigate prospectively the association of caffeinated and decaffeinated beverages with risk of ED in the Health Professionals Follow-up Study (HPFS). In the HPFS, we used an analytic sample of 21,403 men, 7,298 patients with incident ED, and a follow-up period of 10 years. Additionally, we investigated these associations among men with lifestyle factors and comorbid conditions such as obesity, hypertension, diabetes, history of smoking, and marital status.
Am J Epidemiol. 2018;187(5):951-959. © 2018 Oxford University Press