Comparison of Low-Carbohydrate Vs. A Low-Fat Diet on Prostate Cancer Biomarkers

Low-carbohydrate diets slow prostate cancer (PC) growth in mice, but PC-safety is questioned due to high-fat content. In this exploratory, ancillary and hypothesisgenerating study, we compared sera from PC-free men in a randomized trial of low-fat vs. low-carbohydrate diets for weight loss for prostate-specific antigen (PSA) effects and in vitro PC growth. Baseline and week-24 serum were applied to LAPC-4 human PC cells and cell growth was measured (n=21), leaving minimal week-24 serum leftover. PSA was measured using remaining serum from baseline and week-16 (n=15). Low-carbohydrate diet resulted in more weight loss (median 27.1 vs. 9.4lbs, rank-sum p=0.10), although differences were not statistically significant. At week-16, median PSA was 0.69 ng/ml (IQR 0.50-0.94), with no differences between groups (rank-sum p=0.62). There was no correlation between weight loss and PSA change (Spearman r=0.05, p=0.87). Using baseline serum as reference, week-16 serum stimulated cell proliferation was identical between arms (rank-sum p=0.66). Greater weight loss correlated with decreased cell growth (r=-0.50, p=0.03). A low-carbohydrate diet resulted in greater weight loss than low-fat, but no difference in PSA. Although in vitro PC cell growth was unaffected by diet, cell growth was inhibited by weight loss. Lowcarbohydrate diets may lead to greater weight loss and weight loss may inhibit PC growth. Prospective trials in a larger cohort are underway.