Today, the gut microbiota is considered a key organ in host nutritional metabolism and recent data have suggested that alterations in gut microbiota contribute to the development of type 2 diabetes and obesity. Accordingly, a whole range of beneficial effects relating to inflammation and gut health have been observed following administration of probiotics to both humans and different animal models. The objective of this study was to evaluate the metabolic effects of an oral probiotic supplement, Lactobacillus plantarum DSM 15313, to high-fat diet (HFD) fed C57BL/6J mice, a model of human obesity and early diabetes. The mice were fed the experimental diets for 20 weeks, after which the HFD had induced an insulin-resistant state in both groups compared to the start of the study. The increase in body weight during the HFD feeding was higher in the probiotic group than in the control group, however, there were no significant differences in body fat content. Fasting plasma glucose levels were lower in the group fed the probiotic supplement, whereas insulin and lipids were not different. Caecal levels of short-chain fatty acids were not significantly different between the groups. An oral glucose tolerance test showed that the group fed probiotics had a significantly lower insulin release compared to the control group, although the rate of glucose clearance was not different. Taken together, these data indicate that L. plantarum DSM 15313 has anti-diabetic properties when fed together with an HFD.

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Long-term colonic inflammation promotes carcinogenesis and histological abnormalities of the liver, and colorectal tumours frequently arise in a background of dysplasia, a precursor of adenomas. Altered colonic microbiota with an increased proportion of bacteria with pro-inflammatory characteristics, have been implicated in neoplastic progression. The composition of the microbiota can be modified by dietary components such as probiotics, polyphenols and dietary fibres. In the present study, the influence of probiotics in combination with blueberry husks on colorectal carcinogenesis and subsequent liver damage was evaluated. Colorectal tumours were induced in rats by cyclic treatment with dextran sulphate sodium (DSS). Blueberry husks and a mixture of three probiotic strains ( Bifidobacterium infantis DSM 15159, Lactobacillus gasseri , DSM 16737 and Lactobacillus plantarum DSM 15313) supplemented a basic diet fortified with oats. The condition of the rats was monitored using a disease activity index (DAI). A qualitative and quantitative histological judgement was performed on segments of distal colon and rectum and the caudate lobe of the liver. The formation of short-chain fatty acids, bacterial translocation, the inflammatory reaction and viable count of lactobacilli and Enterobaceriaceae were addressed. Blueberry husks with or without probiotics significantly decreased DAI, and significantly reduced the number of colonic ulcers and dysplastic lesions. With a decreased proportion of blueberry husk in the diet, the probiotic supplement was needed to achieve a significant decrease in numbers of dysplastic lesions. Probiotics decreased faecal viable count of Enterobacteriaceae and increased that of lactobacilli. Blueberry husks with or without probiotics lowered the proportion of butyric acid in distal colon, and decreased the haptoglobin levels. Probiotics mitigated hepatic injuries by decreasing parenchymal infiltration and the incidence of stasis and translocation. The results demonstrate a dietary option for use of blueberry husks and probiotics to delay colonic carcinogenesis and hepatic injuries in the rat model.

The aim was to investigate how blueberry husks and/or mixtures of probiotic strains (Lactobacillus crispatus DSM16743, L. gasseri DSM16737 and L. plantarum DSM15313 (LABmix), or Bifidobacterium infantis DSM15159 and DSM15161 (BIFmix)) affect colonic fermentation, caecal counts of lactobacilli, bifidobacteria and Enterobacteriaceae, body weight gain, and blood concentrations of carboxylic acids (CA) and ammonia in rats. Dietary fibres in blueberry husks were fermented to 61 % in colon, and the elevated faecal excretion of fibre and protein contributed to the high faecal bulking capacity (1·3). The caecal pool of CA was higher in rats fed blueberry husks than the fibre-free control (P, 0·05), and the propionic acid proportion was higher in the distal colon than in the control group (P,0·05). Probiotics lowered the caecal amount of CA when added to blueberry husks (P, 0·001), while the propionic acid proportion was higher with LABmix (P, 0·01) than blueberry husks only. The propionic acid and butyric acid concentrations in blood were higher in rats fed blueberry husks and probiotics than those fed blueberry husks only (P,0·01), implying that the absorption of these acids was facilitated by the bacteria. The caecal counts of lactobacilli, bifidobacteria and Enterobacteriaceae were lower in rats fed blueberry husks than the control diet (P, 0·05). The body weight gain was partly influenced by the caecal tissue and contents weights, and BIFmix decreased the ammonia concentration in blood (P,0·05). We conclude that colonic fermentation is differentially affected by dietary fibre and probiotics, which may be of importance when developing foods with certain health effects.

A combination of probiotics and blueberry husks or rye bran enhanced the anti-inflammatory effects compared with probiotics or dietary fibres alone. These combinations can be used as a preventive or therapeutic approach to dietary amelioration of intestinal inflammation.