ProDiet: A Phase II Randomized Placebo-controlled Trial of Green Tea Catechins and Lycopene in Men at Increased Risk of Prostate Cancer

Abstract

Epidemiologic studies suggest that diet can alter prostate cancer risk. This study aimed to establish the feasibility and acceptability of dietary modification in men at increased risk of prostate cancer. Men were invited with a PSA level of 2.0-2.95 ng/mL or 3.0-19.95 ng/mL with negative prostate biopsies. Randomization (3 Â 3 factorial design) to daily green tea and lycopene: green tea drink (3 cups, unblinded) or capsules [blinded, 600 mg flavan-3-ol ()-epigallocatechin-3-gallate (EGCG) or placebo] and lycopene-rich foods (unblinded) or capsules (blinded, 15 mg lycopene or placebo) for 6 months. Primary endpoints were randomization rates and intervention adherence (blinded assessment of metabolites) at 6 months with secondary endpoints of acceptability (from interviews), safety, weight, blood pressure, and PSA. A total of 133 of 469 (28.4%) men approached agreed to be randomized and 132 were followed-up (99.2%). Mean lycopene was 1.28 [95% confidence intervals (CI), 1.09-1.50, P ¼ 0.003] times higher in the lycopene capsule group and 1.42 (95% CI, 1.21-1.66; P < 0.001) times higher in the lycopene-enriched diet group compared with placebo capsules. Median EGCG was 10.7 nmol/L (95% CI, 7.0-32.0) higher in in the active capsule group and 20.0 nmol/L (95% CI, 0.0-19.0) higher in the green tea drink group compared with placebo capsules (both P < 0.001). All interventions were acceptable and well tolerated although men preferred the capsules. Dietary prevention is acceptable to men at risk of prostate cancer. This intervention trial demonstrates that a chemoprevention clinical trial is feasible.

Investigating the effects of lycopene and green tea on the metabolome of men at risk of prostate cancer: The ProDiet randomised controlled trial

“…Our study has several strengths. Firstly, adherence to the ProDiet study was high . Thus, any differences in metabolites across intervention groups at follow‐up are most likely the result of the intervention itself, since all other measured variables were comparable at baseline.…”

“…Briefly, ProDiet was a feasibility randomised‐controlled trial of dietary interventions for prostate cancer prevention. Men were randomised to a daily lycopene arm (active capsules or lycopene‐rich diet or placebo capsules) and a green tea arm (active capsules or green tea drink or placebo capsules) for 6 months in a 3 × 3 factorial design (Fig. ).…”

“…At recruitment, trained nurses collected information on the men's weight, blood pressure, socio‐economic status and medical history . Men were asked to complete a lifestyle questionnaire, which included questions on smoking, alcohol consumption and dietary intake of supplements or vitamins.…”

“…At recruitment, trained nurses collected information on the men's weight, blood pressure, socioeconomic status and medical history. 16,31 Men were asked to complete a lifestyle questionnaire, which included questions on smoking, alcohol consumption and dietary intake of supplements or vitamins. Dietary intake was further assessed using a 117-item food frequency questionnaire (FFQ), which was adapted from the UK arm of the EPIC study 32 (see Supporting Information Methods).…”

“…We recently reported the primary results of a randomised, placebo-controlled factorial trial of lycopene and green tea in men at elevated risk of prostate cancer (ProDiet). 16 Postintervention plasma lycopene and epigallocatechin-3-gallate (ECGC) (a bioactive component of green tea) levels were increased in the respective intervention arms, indicating high levels of adherence. In the present study, we investigated the metabolic effects of lycopene and green tea intake in men enrolled in the same trial, using nuclear magnetic resonance (NMR)-based metabolic profiling.…”