White adipose tissue has an endocrine function that can regulate energy balance, glucose homeostasis and immune function. Obesity is increasingly being seen as a disease of chronic inflammation that results from the effect of excess saturated fat on white adipose tissue. White adipose hormonal regulation becomes dysfunctional by over expansion of adipose tissue, as palmitate over expands the adipose tissue in both size and number. These hypertrophied adipocytes secrete pro-inflammatory cytokines and acute phase proteins such as C-reactive protein that results in systemic inflammation. Free fatty acids release from the enlarged adipocytes stimulate inflammation directly. In addition, lipid-engorged adipocytes undergo apoptosis, resulting in the recruitment of macrophages which causes further pro-inflammatory effects. Reductions in the concentration of adiponectin, an insulin sensitising protein produced by adipocytes, results in insulin resistance. Leptin and resistin levels rise, which may result in energy intake dysfunction and further inflammation, respectively (figure 1).
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Figure 1. The inflammatory effects of excess saturated fatty acids on white adipose tissue. FFA = free fatty acids.
Kennedy, A., Martinez, K., Chuang, C., LaPoint, K. and McIntosh, M. 2009. Saturated fatty acid-mediated inflammation and insulin resistance in adipose tissue: mechanisms of action and implications. Journal of Nutrition. 139: 1-4
