Association of Dietary Patterns With Testicular Function in Young Danish Men

Abstract

Importance: Diet may play a role in testicular function, but data on how adherence to different diet patterns influences human testicular function are scarce.

Objective: To determine whether adherence to specific dietary patterns is associated with testicular function in young men.

Design, setting, and participants: This cross-sectional study included 2935 young Danish men unselected regarding fertility status who were enrolled from April 1, 2008, through May 31, 2017. Data were analyzed from July 1, 2017, to January 30, 2019.

Exposures: Dietary patterns identified with principal component analysis based on responses to a validated food frequency questionnaire.

Main outcomes and measures: Standard semen quality assessment; serum concentrations of testosterone, free testosterone, estradiol, inhibin B, follicle-stimulating hormone, luteinizing hormone, and sex hormone-binding globulin; and testicular volume measured with ultrasonography.

Results: Among the 2935 participants included in the analysis, median age was 19 (interquartile range, 19-20) years and 2290 (78.0%) had normal body mass index. The 4 dietary patterns identified included Western, prudent, open-sandwich (a traditional Danish eating pattern), and vegetarianlike. The greatest adherence to the prudent pattern was associated with the highest total sperm count (median, 167 [95% CI, 146-183] million), followed by adherence to vegetarianlike (median, 151 [95% CI, 134-168] million) and open-sandwich (median, 146 [95% CI, 131-163] million) patterns. Adherence to the Western pattern was associated with the lowest total sperm count (median, 122 [95% CI, 109-138] million), which was significantly lower than sperm count in the other 3 diet patterns. After adjusting for confounders, the median total sperm count for men in the highest quintile of adherence to the Western pattern was 26 million lower (95% CI, -42 to -9 million) than for men in the lowest quintile of adherence to this pattern. Conversely, the median total sperm count of men in the highest quintile of adherence to the prudent pattern was 43 million (95% CI, 23-63 million) higher than that of men in the lowest quintile. Men with the highest adherence to the Western pattern had a lower median ratio of inhibin B to follicle-stimulating hormone (-12 [95% CI, -20 to -3]) and higher median ratio of free testosterone to luteinizing hormone (10 [95% CI, 2-19]) compared with men with lowest adherence to this pattern.

Conclusions and relevance: In this cross-sectional study, adherence to generally healthy diet patterns was associated with better semen quality, with potentially more favorable fertility potential among adult men.

Figure 1.. Food Group Factor Loadings for Dietary Patterns Identified From Food-Frequency Questionnaire Data

We used principal components analysis as an extraction method in which the factor loading of a food group represents the contribution of that food group to the factor (diet pattern) identified. Positive scores indicate higher consumption of the food group; negative scores, avoidance of the food group.

Figure 2.. Adjusted Median Differences in Semen Quality Parameters According to Quintiles of Adherence to Data-Derived Dietary Patterns

Models were adjusted for age, body mass index, height, smoking, use of marijuana and other recreational drugs, moderate-to-vigorous physical activities (hours per week), history of reproductive diseases, reproductive surgical procedures, sexually transmitted diseases, season and calendar year of the sample, mother’s educational level, total energy intake, and abstinence time. Sperm motility models were further adjusted for time elapsed between specimen collection and analysis. Error bars indicate 95% CIs. Tests for trend were conducted across quintiles using the median value in each quintile of the diet patterns as a continuous variable in the regression models, and the P value was based on the Wald test. ^aP < .01. ^bP < .05.

Figure 3.. Adjusted Probabilities of Having Any Semen Parameter Below the World Health Organization (WHO) Lower Reference Limits According to Quintiles of Adherence to Data-Derived Dietary Patterns

The WHO lower reference limits for semen parameters are less than 1.5 mL for semen volume, less than 15 million/mL for sperm concentration, less than 39 million for total sperm count, less than 40% for motile spermatozoa, less than 32% for progressively motile spermatozoa, and less than 4% for normal sperm morphology. Models were adjusted for age, body mass index, height, smoking, use of marijuana and other recreational drugs, moderate-to-vigorous physical activities (hours per week), history of reproductive diseases, reproductive surgical procedures, sexually transmitted diseases, season and calendar year of the sample, mother’s educational level, total energy intake, and abstinence time. Sperm motility models were further adjusted for time elapsed between specimen collection and analysis. For the Western pattern, P = .006 for trend; for the prudent pattern, P = .004 for trend; for the open-sandwich pattern, P = .54 for trend; and for the vegetarianlike pattern, P = .39 for trend.