a1 Department of Food Biosciences, The School of Chemistry, Food Biosciences, and Pharmacy, University of Reading, Reading RG6 6AP UK
a2 Dipartimento di Scienza degli Alimenti, Università di Napoli, ‘Federico II’ Parco Gussone-Ed.84, Portici, NA 80055, Italy
a3 CPUK, Albany Place, Welwyn Garden City, Herts AL7 1RR UK
Epidemiological studies have shown an inverse association between dietary intake of whole grains and the risk of chronic disease. This may be related to the ability to mediate a prebiotic modulation of gut microbiota. However, no studies have been conducted on the microbiota modulatory capability of whole-grain (WG) cereals. In the present study, the impact of WG wheat on the human intestinal microbiota compared to wheat bran (WB) was determined. A double-blind, randomised, crossover study was carried out in thirty-one volunteers who were randomised into two groups and consumed daily 48 g breakfast cereals, either WG or WB, in two 3-week study periods, separated by a 2-week washout period. Numbers of faecal bifidobacteria and lactobacilli (the target genera for prebiotic intake), were significantly higher upon WG ingestion compared with WB. Ingestion of both breakfast cereals resulted in a significant increase in ferulic acid concentrations in blood but no discernible difference in faeces or urine. No significant differences in faecal SCFA, fasting blood glucose, insulin, total cholesterol (TC), TAG or HDL-cholesterol were observed upon ingestion of WG compared with WB. However, a significant reduction in TC was observed in volunteers in the top quartile of TC concentrations upon ingestion of either cereal. No adverse intestinal symptoms were reported and WB ingestion increased stool frequency. Daily consumption of WG wheat exerted a pronounced prebiotic effect on the human gut microbiota composition. This prebiotic activity may contribute towards the beneficial physiological effects of WG wheat.
(Received January 31 2007)
(Revised May 21 2007)
(Accepted June 06 2007)
Abbreviations: WB, wheat bran; WG, whole-grain; TC, total cholesterol