BackgroundSaturated fatty acids are generally thought to have detrimental effects on health. However, a recent study showed that even- and odd-chain saturated fatty acids had opposite associations with type 2 diabetes. Limited studies of Western populations examined the associations of circulating saturated fatty acids with adipokines, an important role in glucose metabolism.ObjectiveWe examined the associations of saturated fatty acids in serum phospholipids with circulating levels of adipokines among a Japanese population.DesignA cross-sectional study was conducted among 484 Japanese employees (284 men and 200 women) aged 20–65 years. The serum fatty acid composition in the phospholipid fraction was measured by gas-chromatography. Serum leptin, adiponectin, plasminogen activator inhibitor-1 (PAI-1), resistin, and visfatin were measured using a Luminex suspension bead-based multiplexed array. Multiple linear regression analysis was performed to assess the association between saturated fatty acids and adipokines, with adjustment for potential confounding variables.ResultsEven- and odd-chain saturated fatty acids were differentially associated with adipokines. Higher levels of even-chain saturated fatty acids (14:0 myristic, 16:0 palmitic, and 18:0 stearic acids) were associated with higher levels of resistin (P for trend = 0.048) and lower levels of adiponectin (P for trend = 0.003). By contrast, odd-chain saturated fatty acids (15:0 pentadecanoic and 17:0 heptadecanoic acids) showed inverse associations with leptin and PAI-1 (P for trend = 0.048 and 0.02, respectively). Visfatin was positively associated with both even- and odd-chain saturated fatty acids.ConclusionsThe results suggest that even- and odd-chain saturated fatty acids are differentially associated with adipokine profile.

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Cholesterol oxidation products (oxycholesterols) are produced from cholesterol by automatic and/or enzymatic oxidation of the steroidal backbone and side-chain. Oxycholesterols are present in plasma and serum, suggesting that oxycholesterols are related to the development and progression of various diseases. However, limited information is available about the absolute amounts of oxycholesterols in organs and tissues, and the physiological significance of oxycholesterols in the body. In the present study, we quantified the levels of 13 oxycholesterols in white adipose tissue (WAT) of mice and then evaluated correlations between each oxycholesterol level and WAT weight. The sum of the levels of 13 oxycholesterols in WAT (white adipose tissue) was 15.9 ± 3.4 μg/g of WAT weight and approximately 1 % of cholesterol level. Among oxycholesterols, the levels of 27-hydroxycholesterol (27-OH), an endogenous oxycholesterol produced by enzymatic oxidation, and the relative WAT weights were significantly negatively correlated. Next, we evaluated the effects of 27-OH on lipogenesis and adipogenesis in 3T3-L1 cells. TO901317 (TO), a potent and selective agonist for LXRα, significantly increased intracellular TAG contents, while 27-OH significantly reduced the contents to half when compared with control (DMSO) and completely abolished the effect of TO. In addition, 27-OH significantly reduced the mRNA levels of lipogenic (LXRα and FAS) and adipogenic genes (PPARγ and aP2) during adipocyte maturation of 3T3-L1 cells. In conclusion, our results indicate that 27-OH suppresses lipid accumulation by down-regulating lipogenic and adipogenic gene expression in 3T3-L1 cells.

Background & aims: Fatty acid composition in diet and serum has been linked to depression, but the evidence on this issue is limited among Japanese, who consume large amounts of fish rich in n-3 polyunsaturated fatty acids. We examined the association between fatty acid composition in serum and depressive symptoms in Japanese men and women. Methods: The subjects were 496 participants aged 21e67 years in a cross-sectional study. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Free, cholesterol ester, and phospholipid fatty acids in serum were measured by gaseliquid chromatography. Multiple logistic regression was used to assess the association between serum fatty acid and depressive symptoms. Results: A higher free alpha-linolenic acid level was marginally significantly associated with a decreased prevalence of depressive symptoms (CES-D ! 16) (P for trend ¼ 0.07). When a cutoff of CES-D ! 19 was used, the association was strengthened; the multivariable-adjusted odds ratios (95% confidence interval) of depressive symptoms for the lowest through highest tertile of alpha-linolenic acid levels were 1.00 (reference), 0.49 (0.29e0.84), and 0.47 (0.26e0.83), respectively (P for trend ¼ 0.007). A higher n-6 PUFA in cholesterol esters and free linoleic acid were also significantly associated with a decreased prevalence of depressive symptoms (CES-D ! 19) (P for trend ¼ 0.03 and 0.048, respectively). The other polyunsaturated fatty acids including marine-derived n-3 PUFA were not associated with depressive symptoms. Conclusions: Fatty acid composition with high levels of serum alpha-linolenic and linoleic acids might be protectively associated with depressive symptoms in Japanese adults.