Association of Diet With Erectile Dysfunction Among Men in the Health Professionals Follow-up Study

Key Points Question Is diet quality associated with risk of erectile dysfunction? Findings In this cohort study among 21 469 men in the Health Professionals Follow-up Study, higher diet quality based on adherence to either a Mediterranean or Alternative Healthy Eating Index 2010 diet, which emphasize the consumption of vegetables, fruits, nuts, legumes, and fish or other sources of long-chain (n-3) fats, as well as avoidance of red and processed meats, was found to be associated with a lower risk of developing erectile dysfunction. Meaning These findings suggest that a healthy dietary pattern may play a role in maintaining erectile function in men.


Introduction
Erectile dysfunction affects an estimated 18 million men in the US, 1 with the disease burden expected to grow as the population ages. Erectile dysfunction is associated with reduced sexual intimacy and health-related quality of life as well as psychological distress for both the affected men and their sexual partners. 2,3 If all affected men sought treatment, treatment costs in the US could reach $15 billion. 4 Modifiable risk factors for erectile dysfunction, particularly among younger men (ie, age <60 years), 5 are largely shared with cardiovascular disease (CVD) and include smoking, obesity, sedentary behavior, diabetes, hypertension, hyperlipidemia, and metabolic syndrome. 6,7 In fact, erectile dysfunction is associated with future CVD and may represent an opportunity to identify and modify shared risk factors. 8 Although evidence-based lifestyle interventions, 9 including healthy dietary patterns, 10,11 are offered to men interested in lowering their CVD risk, it is unknown whether healthy dietary patterns are associated with lower risk of erectile dysfunction.
Studies evaluating the association between diet and erectile dysfunction are limited, and have focused on men with diabetes or prevalent erectile dysfunction. Several small-to moderate-sized randomized clinical trials report that multimodal lifestyle and weight loss interventions improve erectile dysfunction among men with significant cardiovascular risk factors. 12 However, fewer studies have examined the association between a healthy dietary pattern and erectile dysfunction risk, 13,14 and to our knowledge, no prior studies have evaluated the association between adherence to healthy dietary patterns and incident erectile dysfunction in men without diabetes.
We analyzed the association of 2 dietary index scores representative of healthy dietary patterns, the Mediterranean Diet score (MDS) and the Alternative Healthy Eating Index 2010 (AHEI-2010) score, with incident erectile dysfunction in the Health Professionals Follow-up Study, a large prospective cohort study of adult men. We hypothesized that greater adherence to healthy dietary patterns would be associated with lower incident erectile dysfunction, particularly among younger men.

Methods
This study was approved by the Human Subjects Committee at the Harvard T.H. Chan School of Public Health. As approved by the Human Subjects Committee, the return of a questionnaire was considered to imply consent. This study is reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

Participants
The Health Professionals Follow-up Study is a prospective study of US male health professionals who enrolled in 1986 by completing a mailed questionnaire. Detailed methods have been published elsewhere. 15 Briefly, enrolled participants complete a food frequency questionnaire (FFQ) every 4 years and questionnaires that included information regarding lifestyle factors, health outcomes, and medications every 2 years (response rate, 96%).
Of 51 529 men enrolled in 1986, 5510 died prior to 1998; we excluded 8505 men who did not complete the FFQ in 1998, 2551 men who reported a diagnosis of prostate, bladder, or testicular cancer prior to 1998, 445 men who reported implausible energy intake (ie, <800 or >4200 kcal/d),

Assessment of Dietary Patterns
Usual dietary intake of approximately 130 food items was estimated over the previous year using a FFQ completed every 4 years starting in 1986. Participants indicated portion size and frequency of consumption, from never or less than 1 serving per month to 6 or more servings per day. This FFQ has been validated against the standard criterion of repeated 1-week diet records. The mean Pearson correlation coefficient for all foods was 0.63, and 73% of food items had correlation coefficients of 0.50 or greater. 16 Calculation of dietary index scores using self-reported intake of specific food items with a FFQ have been previously published. 17,18 To calculate the MDS index score, participants received 1 point each for consuming above the median intake of vegetables, legumes, fruits and nuts, grains, fish, and the ratio of polyunsaturated to saturated lipids, calculated separately for each dietary questionnaire cycle; 1 point each for consuming less than the median dairy and red or processed meat intake; and 1 point for alcohol intake between 10 and 50 g per day (total score range, 0-9). Monounsaturated fat, used in the traditional MDS, 17 was not used for the lipid ratio because the main dietary contributor of monounsaturated fat in our cohort was beef. 19,20 To harmonize with prior publications, the MDS was reported categorically as low (0-3), moderate (4)(5), and high (6-9) adherence to a Mediterranean dietary pattern. 20 To calculate the AHEI-2010 score, participants were scored on 11 items with predefined criteria for complete adherence vs nonadherence based on the Healthy Eating Pyramid (2010 version). 18,21 Higher intake of fruits, vegetables, whole grains, nuts and legumes, polyunsaturated fats, and ω-3 fatty acids, and lower intake of red and processed meats, sugar-sweetened beverages, trans fatty acids, and sodium contribute to a higher (healthier) dietary index score. Moderate alcohol intake (0.5-2 drinks/d) contributes to a higher index score. Each item is scored from 0 (complete nonadherence) to 10 (complete adherence), with partial scores awarded for proportional intake (total score range: 0-110). The AHEI-2010 score was evaluated by quintile.
To examine associations with individual nutrient and food components, we analyzed each of the dietary index score components categorically using intake servings per week of MDS components and quintiles of AHEI-2010 components.

Outcome Assessment
Starting in 2000, participants were asked to rate their current ability to maintain an erection sufficient for intercourse without treatment as very poor, poor, fair, good, or very good. Each question included a time grid with year and month increments (before 1986, 1986-1989, 1990-1994, 1995 (Figure, A). This inverse association was greatest among men younger than 60 years (P interaction = .003).  (Figure, B). Hazard ratios were also lower among men younger than 60 years compared with older men (P for interaction = .0004) and CIs were more likely to exclude 1.0 in lower quintiles of AHEI-2010 index score among younger men.
When dietary index components were examined separately, higher scores (corresponding to higher intakes) for most healthy components, including vegetables, fruit, legumes, and fish, were associated with lower risk of incident erectile dysfunction. Higher scores (corresponding to lower intakes) for most unhealthy components, including red or processed meat and trans fatty acids, were associated with lower risk of incident erectile dysfunction ( Table 4; eTable in the Supplement). Smoking status, history of hypertension or hyperlipidemia, BMI, and physical activity did not modify the observed associations. These associations were robust in sensitivity analyses when incident CVD during follow-up was removed as a covariate.

Discussion
In this cohort study evaluating the association between a healthy dietary pattern measured by 2 dietary index scores and incident erectile dysfunction among men in various age groups, men with the greatest adherence to a Mediterranean or AHEI-2010 dietary pattern were least likely to develop erectile dysfunction. Inverse associations were strongest among men younger than 60 years using AHEI-2010 score; however, men in the highest categories of either dietary index score had the lowest risk of erectile dysfunction in all age groups. These findings suggest that adherence to healthy dietary patterns is associated with lower risk of erectile dysfunction.      hypertension, depression, antidepressant or antipsychotic medication use, benzodiazepine use, α-blocker or 5α-reductase inhibitor use, incident cardiovascular disease or diabetes during follow-up, caloric intake, and marital status.

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b Higher dietary index score indicates greater adherence to a Mediterranean dietary pattern (total score range: 0-9). Participants received 1 point for intake of healthy components above the median, 1 point for intake of unhealthy components below the median, and 1 point for alcohol intake between 10 and 50 g/d. Exposures were defined as Q.
c P for trend calculated by modeling the median of each Q. d Lower intake indicates less healthy; higher intake, healthier. e Lower intake indicates healthier; higher intake, less healthy.
f Moderate intake indicates healthier; higher and lower intake, less healthy.