Influence of dietary saturated fat content on adiposity, macrophage behavior, inflammation, and metabolism: composition matters

Abstract

We examined the effects of three high‐fat diets differing in the percentage of total calories from saturated fat (SF) (6%, 12%, and 24%), but identical in total fat (40%), on body composition, macrophage behavior, inflammation, and metabolic dysfunction in mice. Diets were administered for 16 weeks. Body composition and metabolism (glucose, insulin, triglycerides, LDL‐C, HDL‐C, total cholesterol) were examined monthly. Adipose tissue (AT) expression of marker genes for M1 and M2 macrophages and inflammatory mediators (TLR‐2, TLR‐4, MCP‐1, TNF‐α, IL‐6, IL‐10, SOCS1, IFN‐γ) was measured along with activation of NFκB, JNK and p38‐MAPK. AT macrophage infiltration was examined using immunohistochemistry. Circulating MCP‐1, IL‐6, adiponectin, and leptin were also measured. SF content, independent of total fat, can profoundly affect adiposity, macrophage behavior, inflammation, and metabolic dysfunction. In general, the 12%‐SF diet, most closely mimicking the standard American diet, led to the greatest adiposity, macrophage infiltration, and insulin resistance (IR), whereas the 6%‐SF and 24%‐SF diets produced lower levels of these variables with the 24%‐SF diet resulting in the least degree of IR and the highest TC/HDL‐C ratio. Macrophage behavior, inflammation and IR following HFDs are heavily influenced by dietary SF content, however, these responses are not necessarily proportional to the SF%. This work was supported by an ASPIRE (Advanced Support Programs for Innovative Research Excellence) grant from the University of South Carolina to E.A.M.Grant Funding Source: ASPIRE