Ammoniated Beef Improves Metabolic Outcomes and Adipose Tissue Function in Diet-Induced Obese Male and Female Mice

Long-term consumption of fatty meats is associated with metabolic diseases, partly because of the induction of low-grade metabolic acidosis.

Our objective was to test the metabolic effects of pH-enhanced (ammoniated) beef in diet-induced obese C57BL/6J mice. We hypothesized that adipose tissue function would be improved by consuming a diet containing pH-enhanced ammoniated beef, compared with non-pH-enhanced beef, and these effects would be modulated by dietary fat content and sex.

Eighty C57BL/6J mice were randomly assigned into 4 groups (n = 20 per group; 10 males and 10 females) and fed diets differing in pH enhancement (ammoniation using ammonium hydroxide) and fat content for 12 wk [low-fat beef (LFB), ammoniated LFB, high-fat beef (HFB), and ammoniated HFB]. Body weights were measured weekly. Visceral (gonadal) white adipose tissue was collected for histology, RNA (qRT-PCR), and protein (Western blotting) analyses. A three-way analysis of variance was performed to identify main effects of fat content, ammoniation, sex, and their interactions.

Interactions between sex and dietary fat content modulated results for weight gain [F (1, 64) = 9.601, P = 0.0029], fat pad mass [F (1, 63) = 36.48, P < 0.0001], and adipocyte area [F (1, 39) = 24.47, P < 0.0001]. Interactions between sex and ammoniation significantly affected fat pad mass [F (1, 63) = 4.341, P = 0.0413] and adipocyte area [F (1, 39) = 4.171, P = 0.0479]. Importantly, ammoniation significantly improved glucose tolerance [F (1, 59) = 16.74, P = 0.0001], irrespective of sex and dietary fat. Interactions between sex and dietary fat content modulated other results throughout the study.

Diets containing ammoniated beef reduced gonadal fat pad mass and adipocyte size, and improved glucose tolerance in mice with diet-induced obesity, whereas interactions between dietary fat content and sex modulated results throughout.