No abstract

The effects of dietary polyphenols on human health have mainly been discussed in the context of preventing degenerative diseases, particularly cardiovascular diseases and cancer. The antioxidant properties of polyphenols have been widely studied, but it has become clear that the mechanism of action of polyphenols extends beyond the modulation of oxidative stress, as they are poorly absorbed from the digestive tract. The purpose of this study was to clarify the effects of polyphenols on the colonic environment, intestinal barrier function, and gut microbiota. We demonstrated that dietary polyphenols derived from aronia, haskap, and bilberry, markedly elevated the amount of fecal mucin and immunoglobulin A (IgA) as an intestinal barrier function and ameliorated the disturbance in gut microbiota caused by a high fat diet in rats. These results suggest that dietary polyphenols play a significant role in the prevention of degenerative diseases through improvement of the colonic environment without any absorption from the digestive tract.

In three separate experiments, we examined the effects of feeding difructose anhydride III (DFAIII) on intestinal calcium (Ca) absorption using female Sprague-Dawley rats (6 wk old) with or without ovariectomy (OVX). In Experiment 1, we showed that Ca absorption was lower in OVX rats fed the 2.0 and 3.0 g Ca/kg diets, but not the 1.0 g Ca/kg diet, than in sham-operated rats during a 3-wk test period. In Experiment 2, we demonstrated that Ca absorption rate in sham and OVX rats fed a diet containing 3% DFAIII was higher than that in rats fed a DFAIII-free diet 4 wk after consuming the test diets. Absorptive activities of everted sacs of the colon, but not of the duodenum, in rats fed DFAIII diet for 4 wk were higher than those in rats fed the control diet. In Experiment 3, we determined which of the small and large intestines is responsible for the effects of DFAIII on Ca absorption using OVX rats with cecocolonectomy or transsection and reanastomosis (sham). Both the sham and cecocolonectomized rats were divided into four subgroups and fed a control, polyethylene glycol (PEG), 1.5% DFAIII or 3% DFAIII diet. We set up the PEG group as another control group to observe the effects of shortening transit time of the small intestine in the DFAIII groups. Promotive effects of DFAIII on Ca absorption were abolished by cecocolonectomy. However, in the cecocolonectomized rats, the Ca absorption rate was still higher in the 1.5 and 3% DFAIII groups than in the PEG group. In conclusion, ovarian hormone deficiency impaired Ca absorption, but the reduction of Ca absorption was restored by feeding DFAIII. J. Nutr. 132: 3387-3393, 2002.

It has been reported that the fruits and leaves of berries such as the blackberry, raspberry, and strawberry contain a high level of scavenging activity for chemically generated active oxygen species. This study investigated the antioxidative activities of black chokeberry fruit (Aronia melanocarpa Elliot) both in vitro and in vivo using the DPPH stable radical and rats with ethanol-induced gastric injury, respectively. The red pigment fraction of the black chokeberry contained three main components, one of which was identified as cyanidin 3-O-beta-glucoside by HPLC analysis and (1)H NMR. The black chokeberry red pigment fraction scavenged >44% of DPPH radicals at a concentration of 25 microg/mL compared to the control solution. The black chokeberry extract and its hydrolysate administrated at 2 g/kg of body weight each had nearly the same protective effect as quercetin administrated at 100 mg/kg of body weight in suppressing the area of gastric mucosal damage caused by the subsequent application of ethanol to <30% compared to the control group. The black chokeberry red pigment fraction had a similarly significant protective effect on gastric mucosa in a dose-dependent manner when administered at 30-300 mg/kg of body weight, and the administration of 30 mg/kg of body weight could suppress ethanol-induced gastric mucosal damage by approximately 50% (ID(50) = 30 mg/kg of body weight).