Lack of effect of walnuts on serum levels of prostate specific antigen: a brief report.

Objective: To examine whether the short-term consumption of walnuts, a food rich in alpha-linolenic acid, affects levels of serum prostate-specific antigen (PSA), a marker of prostate enlargement, inflammation, and cancer.

Methods: Using data from a 12-month randomized crossover study examining the effect of walnut consumption on body composition, we examined whether increased walnut consumption (mean 35 grams daily, 12% total energy) affected serum PSA levels among 40 middle-aged men.

Results: There was no significant difference between mean PSA level at the conclusion of the 6-month walnut-supplemented diet (1.05 mug/L, 95% CI [0.81, 1.37]) and the conclusion of the 6-month control diet (1.06 mug/L, 95% CI [0.81, 1.38]) (P = 0.86) (or a mean proportional decrease in PSA of -1%).

Conclusions: Our results suggest that short-term consumption of walnuts is unlikely to affect PSA levels adversely among otherwise normal men.