Abstract
Consumption of dietary protein at recommended levels is considered a potential strategy to promote satiety and weight management, but how protein from different dietary sources effect the obesity development, lipid metabolism, and gut microbiota is not known. This study focused on the effects of beef, casein, and soy protein diet on lipid metabolism, triglycerides accumulation, and microbial diversity in colon of C57BL/6J mice, which were given either low-fat diets (LFD, 12% Kcal) or high-fat diets (HFD, 60% Kcal) for 12 weeks. Body and liver weight increased significantly in mice fed a beef protein HFD (HFB), whereas reduced cumulative energy intake was seen in a soy protein HFD (HFS) group. HFB-fed mice showed signs of impaired glucose metabolism and insulin resistance along with a significant elevation in the concentration of triglycerides, LDL-cholesterol, total cholesterol, IL1β, TNF-α, IL-6, and leptin in serum. HFB also enhanced lipid accumulation in liver with increased activity of genes important for lipogenesis and hepatic cholesterol metabolism. A 16S rRNA gene sequencing indicated that HFD, regardless of proteins, significantly enhanced the ratio of Firmicutes to Bacteroidetes in colonic microbiota. However, HFB not only reduced the abundance of Akkermansia, compared with LFD independent of proteins, but also decreased the abundance of butyrate-producing bacteria such as Anaerotruncus, Butyricicoccus, and Lactobacillus (P < 0.05) compared with HFS and HFC. In conclusion, consumption of HFB does not only affect the gut microbiota composition but also increases the problems related to metabolic syndromes like dyslipidemia, hypercholesterolemia, and triglycerides accumulation in liver, which lead to systemic inflammation and its associated comorbidities, for example, impaired glucose metabolism and insulin resistance.
Highlights
In past decades, an unprecedented increase has been seen in metabolic syndromes including obesity, diabetes, hyperlipidemia, hyperinsulinemia, and cardiovascular disease (Shang et al, 2017)
We investigated the effects of beef protein, casein, and soy protein in both lean and obese C57BL6/J mice [which were fed high-fat diet (HFD) to induce obesity] by examining lipid metabolism, triglyceride accumulation, insulin resistance, and colonic microbial diversity
Beef protein, regardless of HFD or low-fat diet (LFD), increased glucose resistance compared with soy protein and casein (P = 0.05, Figure 2B), which was further confirmed by the differences observed in IAUC (P < 0.05, Figure 2C)
Summary
An unprecedented increase has been seen in metabolic syndromes including obesity, diabetes, hyperlipidemia, hyperinsulinemia, and cardiovascular disease (Shang et al, 2017). Unfavorable patterns of food intake may cause dysfunctions in lipid metabolism and metabolic syndromes because it has been established that accumulation of lipid and triglycerides in liver results in fatty liver disease, hepatic steatosis, and even diabetes (Maeda et al, 2015; Liisberg et al, 2016). Metabolic syndromes is a constellation of disorders including hyperlipidemia, hyperinsulinemia, hypertension, cardiovascular diseases, and type 2 diabetes (Després et al, 2006; Eckel et al, 2010). High-protein in diet can increase satiating effect and thermogenesis (Weigle et al, 2005). Lysine, arginine, and glycine are reported to have an anti-inflammatory effect (Dort et al, 2013)
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