Addition of Soluble Fiber in Low-Fat Purified Diets Maintains Cecal and Colonic Morphology, Modulates Bacterial Populations and Predicted Functions, and Improves Glucose Tolerance Compared with Traditional AIN Diets in Male Mice

Abstract

Background Purified diets (PDs) contain refined ingredients with one main nutrient, allowing for greater control relative to grain-based diets (GBDs), which contain unrefined grains and animal byproducts. Traditional PDs like the AIN-76A (76A) and AIN-93G (93G) can negatively impact metabolic and gut health when fed long-term, in part due to lower total fiber, no soluble fiber, and higher sucrose content. Objective Two studies were conducted to determine how PDs with reduced sucrose and increased fiber (soluble and insoluble) influence metabolic and gut health in mice compared to traditional AIN PDs or GBDs. Methods In study 1, C57Bl/6N mice (N = 75) consumed a GBD (5002), 76A, 93G, or 2 Open standard PDs (OSDs) with reduced sucrose and higher fiber for 88 days. Body composition and metabolic parameters were assessed. In study 2, C57Bl/6N mice (N = 54) consumed either 2 GBDs (5001 or 5002) or OSDs with different types/levels of fiber for 14 days. Microbiome alterations and predicted functional metagenomic changes were measured. Results OSD marginally influenced body weight and adiposity, but improved glucose tolerance relative to 93G (p = 0.0131) and 76A (p = 0.0014). Cecal and colonic weights were lower in mice fed cellulose-based PDs compared to those fed GBDs and soluble fiber PDs. Soluble fiber diets reduced alpha diversity and showed similar beta diversity, which differed from cellulose fed PDs and GBDs. Certain genera associated with improved gut health such as Bifidobacteria and Akkermansia were significantly elevated by soluble fibers PDs (p≤0.01). Some metabolic pathways related to carbohydrate and fatty acid metabolism were affected by PDs. Conclusion PDs formulated with lower sucrose and increased fiber content, particularly soluble fiber, blunted elevations in metabolic parameters and favorably impacted microbiota and metagenome in C57BL/6N mice.

Purified diets containing high levels of soluble fiber and grain-based diets promote similar gastrointestinal morphometry yet distinct microbial communities

“…We found the addition of soluble fibers in PDs reduced microbial -diversity in cecal and colonic microbial communities. As this observation agrees with reports demonstrating a progressive reduction in α-diversity as the contribution of soluble fiber to a diet increases, it was not surprising to find that a diet containing three sources of soluble fibers also reduced microbial diversity (21,22).…”

“…However, the most popular PDs, including the AIN-76A and AIN-93 series (AIN-93G and AIN-93M), contain only 5% total fiber as cellulose, which is an insoluble fiber and mostly non-fermentable (16)(17)(18). Chassaing et al demonstrated that PDs containing only cellulose increased adipose stores and promoted abnormal GI morphometry in mice relative to mice fed a GBD, and that these observations could be reversed with the replacement (or addition) of inulin to the PDs (19)-others have noted similar findings (20)(21)(22).…”

Characterization and anti-aging effects ofOpuntia ficus-indica(L.) Miller extracts in ad-galactose-induced skin aging model

“…The animals were allowed one week for adaptation in standard cages under standard conditions: 12 h light/12 h dark cycle, humidity 30–60%, temperature 22 ± 3 °C, ad libitum water and food. A standard grain-based diet 52 (3.4 kcal g −1 ; 20% kcal from protein, 67% kcal from carbohydrates and 13% kcal from fat) was used. Ground corn, ground wheat and wheat middlings were the main sources of carbohydrates (48.7% w/w), while dehulled soybeans and soybean oil were the main sources of protein (14.8% w/w) and fat (5% w/w), respectively.…”

Advances in Animal Models and Cutting-Edge Research in Alternatives: Proceedings of the Third International Conference on 3Rs Research and Progress, Vishakhapatnam, 2022

“…), in order to formulate diets for the study of metabolic diseases and other diet-induced phenotypes, including obesity, NAFLD, hypertension, metabolic syndrome and atherosclerosis. 29–31…”

“…), in order to formulate diets for the study of metabolic diseases and other dietinduced phenotypes, including obesity, NAFLD, hypertension, metabolic syndrome and atherosclerosis. [29][30][31] The 3Rs and ongoing efforts to meet deadlines Dr Balaji Bhyravbhatla (Managing Director, Hylasco Bio-Technology Pvt Ltd, India), presented a talk on the importance of identifying the correct types of animals to be used in preclinical experiments and on the best practices involved. Ways to reduce animal use in preclinical testing is an ongoing debate, and stakeholders generally agree that other species (i.e.…”