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Title: Impact of flavonoid-rich and flavonoid-poor fruit and vegetables on biomarkers of cancer risk in a human randomized controlled trial
Author: Sitthiphong, Piyawan
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2013
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Epidemiological studies have shown an association between fruit and vegetable (F&V) consumption and decreased risk of cancer at several sites. However, there are few human intervention studies that provide information about a causal link between F&V consumption and cancer risk and about the optimum amounts of F&V that need to be consumed and whether some types of F&V are more effective than others. This study aims to investigate the impact of increasing intake of flavonoid-rich and flavonoid-poor F&V in human subjects on three endpoints: lymphocyte DNA damage, inflammation markers and gene expression. Blood samples were collected from a randomised, controlled, parallel design study in 80 volunteers divided into three study groups. The participants in the two test groups: high flavonoid F&V (HF) and low flavonoid F&V (LF) were asked to increase F&V intake by 2, 4 and 6 portions/day for duration of 6 weeks each while subjects in the control group (CT) maintained their habitual diet. Increasing F&V intake by 4 and 6 portions/day reduced the endogenous oxidation of DNA bases in the LF group and increasing F&V intake at 6 portions/day enhanced the ability of lymphocytes to resist to exogenously induced ( by H,O,) DNA damage in both test groups. Increasing F&V consumption may reduce chronic inflammation as a consequence of a decrease in the expression of LFA-l in T lymphocytes by HF group at 4 or 6 portions of intake and an increase in the frequency of CCR-9+ on T cells at 6 portions/day when combining HF and LF data. Furthermore, increasing the intake of F&V of either high or low in flavonoids, modulated the expression of gene transcripts involved in cellular defence. In conclusion, increasing of F&V, either HF or LF, can improve cancer risk biomarkers when compared to CT group. However, flavonoid-rich F&V have no additional benefit compared to flavonoid-poor F&V. Moreover, most effects are found at additional amounts of F&V of 6 portions a day.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available