Effect of Korean pine nut oil on hepatic iron, copper, and zinc status and expression of genes and proteins related to iron absorption in diet-induced obese mice

Purpose: Body adiposity is negatively correlated with hepatic iron status, and Korean pine nut oil (PNO) has been reported to reduce adiposity. Therefore, we aimed to study the effects of PNO on adiposity, hepatic mineral status, and the expression of genes and proteins involved in iron absorption. Methods: Five-week-old male C57BL/6 mice were fed a control diet containing 10% kcal from PNO (PC) or soybean oil (SBO; SC), or a high-fat diet (HFD) containing 35% kcal from lard and 10% kcal from PNO (PHFD) or SBO (SHFD). Hepatic iron, copper, and zinc content; and expression of genes and proteins related to iron absorption were measured. Results: HFD-fed mice had a higher white fat mass (2-fold; p < 0.001), lower hepatic iron content (25% lower; p < 0.001), and lower hepatic Hamp (p = 0.028) and duodenal Dcytb mRNA levels (p = 0.037) compared to the control diet-fed mice. Hepatic iron status was negatively correlated with body weight (r = -0.607, p < 0.001) and white fat mass (r = -0.745, p < 0.001). Although the PHFD group gained less body weight (18% less; p < 0.05) and white fat mass (18% less; p < 0.05) than the SHFD group, the hepatic iron status impaired by the HFD feeding did not improve. The expression of hepatic and duodenal ferroportin protein was not affected by the fat amount or the oil type. PNO-fed mice had significantly lower Slc11a2 (p = 0.022) and Slc40a1 expression (p = 0.027) compared to SBO-fed mice. However, the PC group had a higher Heph expression than the SC group (p < 0.05). The hepatic copper and zinc content did not differ between the four diet groups, but hepatic copper content adjusted by body weight was significantly lower in the HFD-fed mice compared to the control diet-fed mice. Conclusion: HFD-induced obesity decreased hepatic iron storage by affecting the regulation of genes related to iron absorption; however, the 18% less white fat mass in the PHFD group was not enough to improve the iron status compared to the SHFD group. The hepatic copper and zinc status was not altered by the fat amount or the oil type.