An exploratory study to determine the effects of a high-fat pH-enhanced beef diet on the gut microbiome in mouse model

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The obesity epidemic is a far-reaching problem that affects people worldwide. Obesity has serious comorbidities such as type 2 diabetes, coronary heart disease, and metabolic syndrome. The increased consumption of the Western Diet in many countries has furthered the obesity problem, as this diet consists of refined sugars and grains, processed meat products, and saturated fats, with little vegetable fiber and minerals from plant products. In combination with a sedentary lifestyle, the Western Diet can result in an increased dietary acid load that has been shown to lead to metabolic endotoxemia and dysbiosis of the gut microbiome if not resolved. It is of interest to investigate ways that we can attenuate the high acid load of the Western Diet in a way that can be easily matriculated into society. One strategy involves increasing the dietary pH of the protein component in the Western Diet, which is largely beef products.

This study suggested that by raising the overall pH of the protein component by ~1 pH unit, there could be a reducing effect on the potential renal acid load of the beef product which could help prevent diet-related dysbiosis and increase the overall diversity and abundance of the gut microbiome compared to a non-enhanced pH high-fat beef diet. Given that flavor plays a major role in food consumption, the pH was only raised ~1 unit to maintain the flavor integrity. Mice were used in this study as their gut microbiome compositions are similar to that of humans. In this study, the treatment groups were fed a high-fat beef diet, like that of the Western Diet, with ground beef that was pre-treated with ammonium hydroxide prior to incorporation into the mouse diet. The control groups were fed a similar high-fat beef diet without the pH-enhancement. To assess the effects of the treatment on the adult population, the mice were sampled at ~16 months old. The DNA was isolated from the mouse feces and was sequenced via whole genome shotgun metagenomics to assess the taxonomic and functional differences between the diet treatment groups and sexes. Results showed that in all groups, both pH-enhanced and control, there was a substantial bloom of Akkermansia muciniphila species. The female enhanced-pH diet group (HFNB-F) demonstrated the largest relative abundance of A. muciniphila, with a relative abundance of about 86%. Other species found include species of the Firmicutes phylum, as well as Proteobacteria, Actinobacteria and Bacteroidetes in order of relative abundance. It is of note that this not typical in high-fat diet studies, which usually find an increased Firmicute:Bacteroidetes ratio and a decreased Verrucomicrobia abundance in obese models. A. muciniphila has been both positively and negatively correlated with obesity as well as age, so this finding adds new insight about this relatively new bacterial species. These findings also suggest that there may be a difference in the way that males and females metabolize ammoniated beef products, as the taxonomic composition between males and females varied. Furthermore, the functional gene profiles between the groups show that despite the similarity in taxonomic profiles, there was great diversity in microbiome gene repertoires. Further study will be needed to explain the role and function of Akkermansia muciniphila within the gut and its relationship with a high-fat beef diet. Additionally, a study into the influence of ammoniated beef products on the gut microbiome will also offer greater insight into the results of this study.

Embargo status: Restricted until 09/2023. To request the author grant access, click on the PDF link to the left.

Gut Microbiome, Obesity, Dietary pH, Beef Diet, Western Diet