Cereal based diets modulate some markers of oxidative stress and inflammation in lean and obese Zucker rats

Extent: 10p.Background: The potential of cereals with high antioxidant capacity for reducing oxidative stress and inflammation in obesity is unknown. This study investigated the impact of wheat bran, barley or a control diet (α-cellulose) on the development of oxidative stress and inflammation in lean and obese Zucker rats. Methods: Seven wk old, lean and obese male Zucker rats (n = 8/group) were fed diets that contained wheat bran, barley or α-cellulose (control). After 3 months on these diets, systolic blood pressure was measured and plasma was analysed for glucose, insulin, lipids, oxygen radical absorbance capacity (ORAC), malondialdehyde, glutathione peroxidase and adipokine concentration (leptin, adiponectin, interleukin (IL)-1β, IL-6, TNFα, plasminogen activator inhibitor (PAI)-1, monocyte chemotactic protein (MCP)-1). Adipokine secretion rates from visceral and subcutaneous adipose tissue explants were also determined. Results: Obese rats had higher body weight, systolic blood pressure and fasting blood lipids, glucose, insulin, leptin and IL-1β in comparison to lean rats, and these measures were not reduced by consumption of wheat bran or barley based diets. Serum ORAC tended to be higher in obese rats fed wheat bran and barley in comparison to control (p = 0.06). Obese rats had higher plasma malondialdehyde (p < 0.01) and lower plasma glutathione peroxidase concentration (p < 0.01) but these levels were not affected by diet type. PAI-1 was elevated in the plasma of obese rats, and the wheat bran diet in comparison to the control group reduced PAI-1 to levels seen in the lean rats (p < 0.05). These changes in circulating PAI-1 levels could not be explained by PAI-1 secretion rates from visceral or subcutaneous adipose tissue. Conclusions: A 3-month dietary intervention was sufficient for Zucker obese rats to develop oxidative stress and systemic inflammation. Cereal-based diets with moderate and high antioxidant capacity elicited modest improvements in indices of oxidative stress and inflammation.Damien P Belobrajdic, Yan Y Lam, Mark Mano, Gary A Wittert and Anthony R Bir

Effects of oat (Avena sativa L.) hay diet supplementation on the intestinal microbiome and metabolome of Small-tail Han sheep

Supplementation of the sheep diet with oats (Avena sativa L.) improves animal growth and meat quality, however effects on intestinal microbes and their metabolites was not clear. This study aimed to establish the effect of dietary oat supplementation on rumen and colonic microbial abundance and explore the relationship with subsequent changes in digesta metabolites. Twenty Small-tail Han sheep were randomly assigned to a diet containing 30 g/100 g of maize straw (Control) or oat hay (Oat). After 90-days on experimental diets, rumen and colon digesta were collected and microbial diversity was determined by 16S rRNA gene Illumina NovaSeq sequencing and metabolomics was conducted using Ultra-high performance liquid chromatography Q-Exactive mass spectrometry (UHPLC-QE-MS). Compared to Control group, oat hay increased the abundance of Bacteroidetes and Fibrobacteres as well as known short-chain fatty acid (SCFA) producers Prevotellaceae, Ruminococcaceae and Fibrobacteraceae in rumen (p &lt; 0.05). In rumen digesta, the Oat group showed had higher levels of (3Z,6Z)-3,6-nonadienal, Limonene-1,2-epoxide, P-tolualdehyde, and Salicylaldehyde compared to Control (p &lt; 0.05) and these metabolites were positively correlated with the abundance of cecal Prevotellaceae NK3B31. In conclusion, supplementation of the sheep diet with oat hay improved desirable microbes and metabolites in the rumen, providing insight into mechanisms whereby meat quality can be improved by oat hay supplementation

RESEARCH Open Access

Dietary resistant starch dose-dependently reduces adiposity in obesity-prone and obesity-resistant male rat

Evaluation of an Ileorectostomised Rat Model for Resistant Starch Determination

The human ileostomy model, widely considered the benchmark for determining in vivo starch digestibility, has disadvantages. The ileorectostomised rat model (IRM) is a possible surrogate but evidence as to its validity is scant. In this preliminary study, the resistant starch (RS) content of test breads made from refined low (LAW-R) and high amylose wheat (HAW-R) flours was established in a randomised cross-over trial involving six human ileostomy participants. Starch digestibility of refined breads and diets made from these flours was then evaluated in ileorectostomised rats using a similar experimental format. Physical performance measures and other data were also collected for the rat model. The amount of RS in the low- and high-amylose breads as measured using the human model was 0.8 &plusmn; 0.1 and 6.5 &plusmn; 0.3 g/100 g, respectively. The RS level of HAW-R bread determined using ileorectostomised rats was 5.5 &plusmn; 0.8 g/100 g, about 15% less than that recorded in the human study, whereas for conventional wheat breads the models produced similar RS values. While offering promise, further validation using a wide variety of starchy food products is needed before the IRM can be considered an acceptable alternative for RS determination

Determining the Glycaemic Index of Standard and High-Sugar Rodent Diets in C57BL/6 Mice

The glycaemic index (GI) is a useful tool to compare the glycaemic responses of foods. Numerous studies report the favorable effects of low GI diets on long term metabolic health compared with high GI diets. However, it has not been possible to link these effects to the GI itself because of other components such as macronutrients and dietary fibre, which are known to affect GI. This study aimed to create and evaluate isocaloric diets differing in GI independent of macronutrient and fibre content. The GIs of eight diets differing in carbohydrate source were evaluated in mice; cooked cornstarch (CC), raw cornstarch (RC), chow, maltodextrin, glucose, sucrose, isomaltulose, and fructose. A glucose control was also tested. The GIs of all eight diets were different from the GI of the glucose control (GI: 100; p &lt; 0.0001). The GIs of the glucose (mean &plusmn; SEM: 52 &plusmn; 3), maltodextrin (52 &plusmn; 6), CC (50 &plusmn; 4), RC (50 &plusmn; 6), and chow (44 &plusmn; 4) diets were similar, while the GIs of the sucrose (31 &plusmn; 4), isomaltulose (24 &plusmn; 5), and fructose (18 &plusmn; 2) diets were lower than all other diets (p &lt; 0.05). This is the first trial to report GI testing in vivo in mice, resulting in three main findings: chow is relatively high GI, the glucose availability of raw and cooked cornstarch is similar, and the GI of different sugar diets occur in the same rank order as in humans

Soy and Gastrointestinal Health: A Review

Soybean is the most economically important legume globally, providing a major source of plant protein for millions of people; it offers a high-quality, cost-competitive and versatile base-protein ingredient for plant-based meat alternatives. The health benefits of soybean and its constituents have largely been attributed to the actions of phytoestrogens, which are present at high levels. Additionally, consumption of soy-based foods may also modulate gastrointestinal (GI) health, in particular colorectal cancer risk, via effects on the composition and metabolic activity of the GI microbiome. The aim of this narrative review was to critically evaluate the emerging evidence from clinical trials, observational studies and animal trials relating to the effects of consuming soybeans, soy-based products and the key constituents of soybeans (isoflavones, soy proteins and oligosaccharides) on measures of GI health. Our review suggests that there are consistent favourable changes in measures of GI health for some soy foods, such as fermented rather than unfermented soy milk, and for those individuals with a microbiome that can metabolise equol. However, as consumption of foods containing soy protein isolates and textured soy proteins increases, further clinical evidence is needed to understand whether these foods elicit similar or additional functional effects on GI health

A high-whey-protein diet reduces body weight gain and alters insulin sensitivity relative to red meat in Wistar rats

© 2004 The American Society for Nutritional SciencesA high-protein diet can reduce body weight and increase insulin sensitivity, but whether the type of dietary protein affects these outcomes is unknown. We hypothesized that feeding insulin-resistant rats a high-protein diet (32%) containing whey protein concentrate (WPC) would reduce body weight and tissue lipid levels and increase insulin sensitivity more than a diet containing red meat (RM). Rats were fed a high-fat diet (300 g fat/kg diet) for 9 wk, then switched to a diet containing either 80 or 320 g protein/kg diet, provided by either WPC or RM, for 6 wk (n = 8). The rats were then killed after overnight food deprivation. High dietary protein reduced energy intake (P < 0.001) and visceral (P < 0.001), subcutaneous (P < 0.001), and carcass fat (P < 0.05). Increasing the dietary density of WPC, but not of RM, reduced body weight gain by 4% (P < 0.001). Dietary WPC also reduced plasma insulin concentration by 40% (P < 0.05) and increased insulin sensitivity, compared to RM (P < 0.05). These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity.Damien P. Belobrajdic, Graeme H. McIntosh, and Julie A. Owen

An arabinoxylan-rich fraction from wheat enhances caecal fermentation and protects colonocyte DNA against diet-induced damage in pigs

Published online: 24 November 2011Population studies show that greater red and processed meat consumption increases colorectal cancer risk, whereas dietary fibre is protective. In rats, resistant starches (a dietary fibre component) oppose colonocyte DNA strand breaks induced by high red meat diets, consistent with epidemiological data. Protection appears to be through SCFA, particularly butyrate, produced by large bowel carbohydrate fermentation. Arabinoxylans are important wheat fibre components and stimulate large bowel carbohydrate SCFA production. The present study aimed to determine whether an arabinoxylan-rich fraction (AXRF) from wheat protected colonocytes from DNA damage and changed colonic microbial composition in pigs fed with a diet high (30 %) in cooked red meat for 4 weeks. AXRF was primarily fermented in the caecum, as indicated by higher tissue and digesta weights and higher caecal (but not colonic) acetate, propionate and total SCFA concentrations. Protein fermentation product concentrations (caecal p-cresol and mid- and distal colonic phenol) were lower in pigs fed with AXRF. Colonocyte DNA damage was lower in pigs fed with AXRF. The microbial profiles of mid-colonic mucosa and adjacent digesta showed that bacteria affiliating with Prevotella spp. and Clostridial cluster IV were more abundant in both the mucosa and digesta fractions of pigs fed with AXRF. These data suggest that, although AXRF was primarily fermented in the caecum, DNA damage was reduced in the large bowel, occurring in conjunction with lower phenol concentrations and altered microbial populations. Further studies to determine the relationships between these changes and the lowering of colonocyte DNA damage are warranted.Damien P. Belobrajdic, Anthony R. Bird, Michael A. Conlon, Barbara A. Williams, Seungha Kang, Christopher S. McSweeney, Dagong Zhang, Wayne L. Bryden, Michael J. Gidley and David L. Toppin