Deep subcutaneous adipose tissue is more saturated than superficial subcutaneous adipose tissue

Upper body abdominal subcutaneous adipose tissue (SAT) can be divided into deep SAT (DSAT) and superficial SAT (SSAT) depots. Studies on adipose tissue fatty acid (FA) composition have made no distinction between these two depots. The aim of this study is to determine whether DSAT and SSAT differ in FA composition. We studied the FA composition of DSAT and SSAT in 17 male and 13 female volunteers using non-invasive proton magnetic resonance spectroscopy in vivo. Magnetic resonance imaging was used to differentiate between DSAT and SSAT. Adipose tissue spectra were analysed for lipid unsaturation, or double bond (DB) content, and polyunsaturation (PU), according to previously validated methods. The DSAT depot was more saturated than the SSAT depot, in both men (0.833±0.012 vs 0.846±0.009 DB, P<0.002) and women (0.826±0.018 vs 0.850±0.018 DB, P<0.002). In contrast, PU did not differ between DSAT and SSAT in either men (0.449±0.043 vs 0.461±0.044 PU, P=0.125) or women (0.411±0.070 vs 0.442±0.062 PU, P=0.234) and displayed a close correlation between the depots (R=0.908, P<0.001, n=30). The higher saturation in DSAT compared with SSAT can be attributed to a higher ratio of saturated to monounsaturated FAs. These results should be taken into account when determining the FA composition of SAT.