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Publication - Miss Caroline Bull

    Effect of green tea and lycopene on the insulin-like growth factor system (IGFs)

    the ProDiet randomised controlled trial

    Citation

    Biernacka, K, Holly, JMP, Martin, R, Frankow, A, Bull, C, Hamdy, F, Donovan, J, Neal, DE, Metcalfe, C & Lane, JA, 2019, ‘Effect of green tea and lycopene on the insulin-like growth factor system (IGFs): the ProDiet randomised controlled trial’. European Journal of Cancer Prevention.

    Abstract

    Purpose: Whether prostate cancer (PCa) may be preventable by dietary interventions can be assessed in randomised trials using intermediate biomarkers of cancer risk or progression. We investigated whether lycopene or green tea modify circulating insulin-like growth factor (IGF) peptides in men at increased risk of PCa.
    Methods: Participants (aged 50-69 years) in one centre in a UK wide PCa testing and treatment trial (ProtecT) with PSA between 2.0-2.95 ng/ml or negative biopsies, were randomised to daily lycopene (n=44 assigned 15mg capsules/day; 44 assigned a lycopene-rich diet; 45 assigned placebo) and green tea (n=45 assigned 600mg/day epigallocatechin gallate (EGCG); 45 assigned green tea drink; 43 assigned placebo) for 6 months. The interventions significantly elevated the primary outcomes, serum EGCG and lycopene at 6 months follow-up. We report here an exploratory analysis in which serum IGF-I, IGF-II, IGF binding protein (BP)-2 and IGFBP-were measured at baseline and 6-months post intervention. 133 men were randomised (34% of eligible men approached) and 130 had follow-up IGF peptides (98%).

    Results: In intention-to-treat analyses, there was only weak evidence that lycopene or green tea influenced some aspects of serum IGF-I, IGF-II, IGFBP-2 or IGFBP-3. In men randomised to lycopene supplements, IGFBP-2 was non-significantly 50.9 ng/ml (95%CI; -51.2, 152.9, p=0.3) higher in comparison to placebo whilst in men randomised to green tea supplements, IGFBP-3 was non47 significantly 205.2 ng/ml (95%CI: -583.3, 172.9, p=0.3) lower than with placebo.
    Conclusions: In this small, pilot randomised controlled trial, there was little evidence that lycopene or green tea interventions influenced serum levels of IGF-I, IGF-II, IGFBBP-3 and IGFBP-2. However, the effects were imprecisely estimates and some observed trends may justify larger trials.

    Full details in the University publications repository