Metabolic Effects of Dietary pH, Protein Source and Fat Content in Diet-induced Obese Mice

Higher intake of saturated fats, salts, and fatty proteins has been linked to metabolic diseases (e.g., obesity), in part through low-grade metabolic acidosis and inflammation. Hence, our objective was to test the effects of protein sources and preparations in diet induced obese B6 male and female mice, compared to low fat-fed mice. We hypothesized that metabolic health will be improved by consuming a diet containing pH-enhanced beef or casein diets, compared to a non-pH-enhanced diets. B6 male and female mice were randomized (n = 10) into 8 diets that differ in protein source, pH enhancement, and fat content: low fat casein (LFC), pH-enhanced (with ammonia) LFC (LFCN), LF lean beef (LFB), LFBN, high fat casein (HFC), HFCN, HF beef (HFB), HFBN. Body weight and food intake were measured weekly for 12 weeks. White adipose tissue (WAT) was collected at study termination and used for histology, RNA and protein isolation for analyses of fat cell size, and gene (qRT-PCR) and protein (Western blotting) expression. Three-way ANOVA was performed to identify main effects as well as interactions of dietary pH x protein source x fat content, separately in males, and females. We identified a significant main effect of diet (LF/HF) on fat pad weights in males (F (1,71) = 91.94, p < 0.0001) and females (F (1,72) = 5.111, p = 0.0268). No effect of protein source or change of dietary pH was observed on fat pad weights. However, WAT histology indicated a substantial change in adipose tissue quality, with reduced adipocyte area (p < 0.05) in LF, LFN, HFCN, HFB, HFBN groups compared to HFC in males. Additionally, in both males and females, protein levels of pAkt and pAMPK were upregulated in adipose tissue of mice fed HF diets with increased pH (HFCN, HFBN), compared to non-pH enhanced HF diets. Our findings indicate potential metabolic benefits of increasing dietary pH, as shown by improved adipose tissue cellularity and improved insulin signaling and energy sensing/fat oxidation-related markers. Thus, additional research is warranted to determine mechanisms underlying the metabolic effects of pH enhancement. These findings also merit further mechanistic studies in animals, as well as future clinical research to translate our results into humans and dissect interactions between protein source, pH and fat content on metabolic diseases. Empirical Foods.