Serum levels of folate and prostate-specific antigen among US men

Background Results from epidemiologic studies relating folate status to prostate cancer are controversial. This study investigates the association between levels of serum folate and prostate-specific antigen (PSA), a biomarker for prostate cancer detection. Methods Using data from the 2007-2010 National Health and Nutrition Examination Survey, 2,198 men aged 40 years and older with serum PSA and folate measures were studied. Total PSA (tPSA) and percent free/total PSA ratio (%fPSA) were outcomes of interest. The alternative cutpoints were used to categorize as higher risks of prostate cancer (tPSA: ≥10 and ≥4 ng/ml; %fPSA: ≤25%). Serum levels of folate was defined as quintiles and examined as risk/protective factors for PSA biomarkers. Multivariate logistic regression was applied to estimate odds ratios (OR) and 95% confidence interval (CI). Results Linear regression found that higher serum folate was associated with decreased log10-transformed tPSA (β=-0003, p=0.003) and increased %fPSA (β=0.082, p=0.011). Adjusting for age, race/ethnicity, socioeconomic status, body mass index, use of non-steroidal anti-inflammatory drugs and smoking, higher folate levels were associated with lower odds of having higher tPSA (≥10 ng/ml, OR associated with fifth to first quintile of folate = 0.36, 95% CI=0.16-0.84, p for trend=0.021) and lower %fPSA (≤25%, OR [fifth vs. first quintile of folate] = 0.54, 95% CI=0.35-0.82, p for trend=0.006). Conclusion The study suggests that higher folate status may protect against elevated total PSA levels among men without diagnosed prostate cancer. Further studies are necessary to confirm this finding and to investigate potential mechanisms that may explain this relationship.