Increased Intake of Healthful Plant-Based Foods Associated with Lower PSA Levels

Men who reported eating a plant-based diet more frequently had lower levels of prostate-specific antigen (PSA), but whether plant-based diets play a role in prostate cancer risk has yet to be fully determined, according to a study presented by Ali Mouzannar, MD, of the Jackson Memorial Hospital, at the 2021 American Urological Association Annual Meeting.

Practice patterns suggest diet modification, among other lifestyle changes, have been increasingly used in recent years to mitigate PSA levels, in conjunction with other strategies. In a new study, Dr. Mouzannar and colleagues examined the association between a plant-based diet and PSA levels in 1,399 men (median age, 54 years; age range, 46-63 years) in the National Health and Nutrition Examination Survey (NHANES).

For this cohort, the researchers calculated the participants’ plant-based diet index (PDI) and healthful plant-based diet index (hPDI) as based on data from food frequency questionnaires. Individuals with higher PDI and hPDI had higher intakes of plant foods and healthy plant foods, respectively. The abstract presentation didn’t differentiate the two indices with regard to what foods constitute the PDI and the hPDI.

The NHANES database also provided data on patient demographics, dietary patterns, and levels of PSA. Researchers examined the association between plant-based diet indices and elevated PSA, clinical variables, and demographics in a multivariable-adjusted logistic regression analysis.

While the median PSA level across the cohort was 0.9 ng/dL, nearly 5% (n=69) of men in the study had an elevated PSA level of 4 ng/dl. There was no significant association between elevated PSA and PDI; however, multivariable analysis revealed that patients who had a higher consumption of healthy plant-based diet, as evidenced by high hPDI scores, also had a decreased odds of elevated PSA levels (odds ratio=0.47; 95% CI, 0.24-0.95; p=0.034).

A limitation of the study included the reliance on food frequency questionnaires, which are prone to error and recall bias. Despite these findings, the researchers indicate the study adds to the literature regarding lifestyle modifications and the effects of these changes on PSA. Additionally, given the study included men up to 63 years of age, the findings may lack generalizability across an older male population.

Dr. Mouzannar and colleagues wrote that based on these findings, a healthy plant-based approach could be introduced into a shared-decision making model with patients with elevated PSA in an effort to promote healthier lifestyle choices and subsequently “reduce the likelihood of prostate biopsy and potential treatment-related morbidity.”