Do plant-based diets improve men’s urologic health?

"Although the effects of a plant-based diet on the cardiovascular system and endocrine system are well-documented and very well-studied, the effect on erectile function [is not fully understood]," says Ruben Blachman-Braun, MD.

Studies presented at the 2021 American Urological Association’s Annual Meeting found that men who follow plant-based diets exhibit improvements in their urologic health.

The results of 1 study, presented and co-authored by Ali Mouzannar, MD, suggest that plant-based diets reduce prostate specific antigen (PSA) levels.1 Outcomes from another study, presented and co-authored by Ruben Blachman-Braun, MD, show that plant-based diets can lower the risk of erectile dysfunction (ED).2 Both studies analyzed data from the National Health and Nutrition Examination Survey (NHANES) and were conducted at the University of Miami Miller School of Medicine, Miami, Florida.

Plant-based diets and PSA level

In the first study, investigators used a multivariable-adjusted logistic regression analysis to assess the relationship between plant-based dietary patterns and PSA levels in 1399 patients from the NHANES database (2003-2006).

“Studies have shown that more aggressive prostate cancer can be associated with high meat intake. In addition, there is growing evidence that animal-based food has been associated with greenhouse emissions, and all-cause mortality risk,” said Mouzannar in a news release.3 “Several other publications suggest that fruits and vegetables may have protective effect against prostate cancer.”

To collect dietary data, a plant-based diet index (PDI) and healthful plant-based diet index (hPDI) were calculated from the National Cancer Institute’s Food Frequency Questionnaire (FFQ). Both indexes were formed based on the consumption of animal products, healthful plants foods, and less-healthful plant foods. Higher scores on PDI and hPDI translated to higher consumption of plant-based or healthful plant-based food.

The median age of the enrolled patients was 54 years (range, 46-63 years), the median prostate-specific antigen (PSA) level was 0.9 ng/mL (0.6-15 ng/mL), and 69 patients(4.9%) had a PSA level of greater than or equal to 4 ng/dL.

Results showed that patients who were Black and of older age had higher PSA levels and that even though elevated PSA was not associated with elevated PDI, elevated hPDI was associated with a decreased risk of elevated PSA (OR=0.47, 95% CI:0.24-0.95; P =.034).

Although these findings provide some favorable grounds for plant-based diets, the NHANES database is cross-sectional and lacks information regarding changes in dietary behavior among patients as well as comorbidities that can potentially alter PSA values. In addition, the FFD is associated with recall bias and there could be confounding factors in men who exhibited high PDI or hPDI. Further research must be conducted.

In the concluding remarks of his presentation, Mouzannar said, “Clinicians may incorporate the aforementioned findings during the shared decision-making process to promote healthier lifestyle choices and this can potentially reduce the likelihood of prostate biopsy and associated treatment morbidity.”

Plant-based diets and ED risk

In the second study, data of 2549 patients from the NHANES III database (1988-1994) were analyzed to evaluate the relationship between plant-based dietary patterns and erectile dysfunction.

Explaining the background of this study, Blachman-Braun said, “There is an increasing trend worldwide to change to [a] plant-based diet…Although the effects of a plant-based diet on the cardiovascular system and endocrine system are well-documented and very well-studied, the effect on erectile function [is not fully understood].”

Similar to the PSA study, investigators obtained data on demographics, diet, and degree of erectile dysfunction. An hPDI was formed using the FFQ and an SPSS 24 statistical analysis was performed as well as a multivariable-adjusted logistic regression analysis to determine the association between ED and hPDI.

Patients were excluded from enrollment in this study if they were less than 20 years of age, greater than 70 years of age, had incomplete PDI information, had a history of prostate cancer, or had missing information.

Of the patients who were enrolled, 1464 (57.4%) had some degree of ED. A total of 521 men (20.4%) usually had erections, 690 men (27.1%) sometimes had an erection, and 253 men (9.9%) never had erections. The median age was 54 years (range, 41-64 years) and median body mass index (BMI) was 28.8 (25.5-32.6) kg/m2.

Analysis of PDI showed varying dietary patterns among men in different ED groups (P < .05) and an hPDI of 50 (45-56). There was also a correlation between increasing age and worsening ED and increasing BMI and worsening ED, as well as a significant difference in degree of ED among patients of different races, degrees of hypertension, diabetes status, stroke history, cancer history, and smoking status.

Additionally, results found that Increased age, body mass, hypertension, diabetes, stroke history, and smoking history were all clinical variables associated with ED. However, there was a negative association between hPDI and ED (OR=0.98, 95% CI: 0.96-0.99; P = .001).

“This does not mean that eating a plant-based diet improves erections. However, it shows that eating a plant-based diet does not negatively affect erections and having a healthier lifestyle with increased dietary plant-based consumption can potentially lead to having better erections,” said Blachman-Braun in the news release.3

References

1. Mouzannar A, Kuchakulla M, Blachman-Braun R, et al. Impact of plant-based diet on PSA level: data from the national health and nutrition examination survey. Paper presented at: 2021 American Urological Association Annual Meeting; September 10-13, 2021; virtual. Abstract PD65-08

2.Kresch E, Blackman-Braun R, Nackeeran S, et al. Plant based diets are associated with decreased risk of erectile dysfunction. Paper presented at: 2021 American Urological Association Annual Meeting; September 10-13, 2021; virtual. Abstract PD20-05

3. University of Miami urologists study how plant-based diets impact men’s health. Newswise. September 23, 2021. Accessed August September 30, 2021. https://www.newswise.com/articles/university-of-miami-urologists-study-how-plant-based-diets-impact-men-s-health?sc=mwhr&xy=10016681