Study Of Prebiotic Effects Of Whole Grain On Intestinal Microbiota

Epidemiological studies have shown an inverse association between dietary intake ofwhole grains and the risk of chronic disease. This may be related to their potential ability tomediate a prebiotic modulation of gut microbiota. However, little is known about themicrobiota modulatory capability of whole grain or the impact of ingredients on this ability.Whole grains are rich in nutrient substance and phytochemicals. Studies have providedevidence that whole grains are protective against a wide range of diseases as a whole, andgenerally this protectiveness is greater than that seen with any individual ingredient.Five whole grains(oat, barley, whole wheat, black rice) and a refined grain were chosedas objects in this study. First of all the impact of whole grain on intestinal microbiota and theirmetabolite short chain fatty acids (SCFA) were studied, correlation analysis between intestinalmicrobiota, SCFA and ingredient were also evaluated. The results show that after fermentation,bifidobacterium in whole grain samples increased significantly; lactobacillus also increasedsignificantly in all whole grain samples except black rice; while enterobacteriaceae andclostridium in whole grain samples derceased significantly. Polished rice showed significantdecreases in bifidobacterium and lactobacillus, and increases in enterobacteriaceae andclostridium, especially enterobacteriaceae which increased from7.23lg(cfu)/mL to8.04lg(cfu)/mL after fermentation. Compared to0h,5h and10h, significant increases inconcentration of SCFAs were observed in whole grain samples after24h fermentation.Although significant increases compared with0h were also observed after fermentation inpolished rice, concentration of SCFAs were pretty low compared with whole grain samples. Invitro prebiotic effects of samples were evaluated by prebiotic index (PI). After fermentation,PI of oat was the biggest, which reached up to0.235, followed by whole wheat, barley, brownrice and black rice, the least PI was-0.098obtained from polished rice, which indicates thatpolished rice has no prebiotic effect. B/E value was also calculated to evaluate the structure ofintestinal microbiota. After fermentation, B/E value of oat and barley was1.17, which tied forfirst place, followed by whole wheat1.16, brown rice1.14, black rice1.11and polished rice0.88. Results above indicate that intestinal microbiota of whole grain samples were wellstructured after fermentation while polished rice was not.Correlation analysis between main components of samples and changes in number ofintestinal microbiota as well as in concentration of SCFAs was performed. Significant positivecorrelation was observed between total, soluble and insoluble dietary fibre andbifidobacterium as well as lactobacilus, and significant negetive correlation was alsoobserved between total, soluble and insoluble dietary fibre and enterobacteriaceae as well ascolstridium. Total phenolic and combined phenol showed significant inverse associations withenterobacteriaceae and colstridium while no significant correlation with bifidobacterium and lactobacilus was found. Results above indicate that total dietery fibre, soluble dietery fibre,insoluble dietery fibre, total phenoilc and combinded phenol all have effect on modulatingintestinal micrbiota, the prebiotic effects of whole grain is the result of the synergy of itsvarious components. In addition, correlation analysis between components and SCFAsshowed that dietary fibre also has the effect of promoting SCFA producing bacteria,particularly the propionic acid producing bacteria to metaboliz SCFAs.Effects of intaking whole grains on mice was evaluated on the basis of in vitroexperiments. The results reconfirmed the benificial regulating effects of whole grains onintestinal microbiota. Compared to polished rice intaking group and control group, numbersof bifidobacterium and lactobacillus were significantly high in mice of whole grain intakinggroups, and oat group was the biggest. Numbers of bifidobacterium and lactobacillus in oatgroup were9.51lg(cfu)/mL and8.55lg(cfu)/mL respectively, while only9.01lg(cfu)/mL and7.93lg(cfu)/mL respectively in polished rice group. What’s more, fecal moisture content ofwhole grains intaking groups were higher than that of polished rice and control group. Itindicate that whole grains have the effect of improving intestinal environment. In addition,feed to gain ratio of whole grain intaking groups were also higher than polished rice intakinggroup and control group, which means that whole grains have the effects of controlling bodyweight as well.