Research indicates that fruit, vegetable and cereal consumption, and the insoluble fibre and polyphenols they contain, may have an impact on the gut microbiota, which in turn may enhance colon health. In this Thesis we have investigated the potential of dates, which are a rich source of both fibre and polyphenols, to enhance gut health. Initially, we undertook chemical analysis of different date varieties before investigating the impact of date fruit intake on intestinal health using in vitro models and a human trial. Data indicated that Ajwa dates (AJD) were the richest in both polyphenols (phenolics acids, flavonoids glycosides and anthocyanins) (22 .87mglI00g expresses as GAE; 1500mgll00g in weight) and 6.85-7.9g1100 g of dietary fibres (6.15-7.2 insoluble).Utilizing pH-controlled batch cultures, we show that faecal microbiota growth was significantly altered by both date polyphenol extracts (DPE) and digested date fruits (DOE). DDE (I.Sg) exhibited a higher impact on the gut ecology, with significant increases in bifidobacteria, bacteroides and total bacteria along with increases in SCFAs (acetate). The impact of OPE (1S0mglml) was less profound, where only bifidobacteria growth was enhanced at earlier fermentation periods and significant reductions were seen in cleaved aglycones (myricetin, luteolin, quercetin, apigenin and petunidin). DPE & ODE were also shown to exert antiproliferative effects on colon adenocarcinoma cell growth, both before and after bacterial fermentation, with DDE (0.2mg/ml) inducing significantly more inhibition (80% growth inhibition) than DPE (0.2mglml). With regards to the human trial, twenty-two volunteers consumed SOg AJD dates (7peices) or 40 g of a control product (maltodextrin/dextrose mix) for 21 d. Date consumption significantly reduced the potential of human faecal water to induce DNA damage in colon cells, as evidenced using the COMET assay, compared to the control (p<O.OS). In addition, ammonia concentrations were seen to exhibit a significant trend in reducing following AJD consumption, relative to control (p>O.OS). Date consumption also led to a significant increase in stool frequency compared to the control, without indications of diarrhoea or bloating. Lastly, there were no significant changes in the growth of the intestinal microbiota in response to date intake, although this finding may have been confounded by the high dietary fibre intake of our study population at baseline and variations in faecal microbial composition between volunteers. Our findings show that date consumption may enhance colon health, without inducing large changes in bacterial growth.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:617032 |
| Date | January 2014 |
| Creators | Eid, Noura Mohammed Saleh |
| Publisher | University of Reading |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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