Weight, metabolic improvements with low-carb diet have null effect on cancer progression

Prostate cancer patients with biochemical recurrence (BCR) may benefit from a low-carbohydrate diet (LCD), which leads to weight loss and metabolic improvements, but these effects have no positive impact on tumour growth, as shown in the results of a trial.

The 6-month randomized trial examined the effect of LCD (n=31) vs a no-intervention control (n=26) on prostate-specific antigen (PSA) doubling time (PSADT) in men with prostate cancer with BCR after local treatment. All participants had body mass index (BMI) ≥24 kg/m² and PSADT of 3–36 months. The LCD arm was instructed to eat ≥20 g/carbs/day.

The study was discontinued prematurely after an interim analysis showed futility. A total of 27 LCD and 18 control patients completed the study.

At 6 months, both groups had similar intake of protein and fats, although patients in the LCD group had greater reductions in carbohydrates intake (−117 vs 8 g; p<0.001) and in weight (−12.1 vs −0.50 kg; p<0.001). Furthermore, LCD was associated with decreases in high-density lipoprotein cholesterol, triglycerides, and HbA1c, with no difference in total cholesterol or glucose.

The primary outcome of PSADT was comparable between the LCD and control groups (mean, 21 vs 15 months; p=0.316). A posthoc exploratory analysis accounting for prestudy PSADT, baseline PSA, primary treatment, and haemoconcentration showed that the outcome was significantly longer in the LCD group (28 vs 13 months; p=0.021).

Adverse events occurred infrequently, generally mild in severity, and returned to baseline by 6 months.

In light of the exploratory findings of longer PSADT, larger studies testing LCD on disease progression are needed.