ABSTRACT
There is evidence on reciprocal effects of insulin and desacylghrelin [DAG], but associations between secretions of hormones [insulin and DAG] and saturated and unsaturated proportions of edible oils in high-fat diets have not been studied. The aim of this study was to investigate the impact of different sources of dietary fat and the extent of fatty acid saturation on plasma insulin and DAG levels and determine the association between DAG and insulin action in rats. Weaning male Wistar rats were randomly divided into four groups to be fed on one of 4 high-fat diets containing, as the source of fat, butter [HF-b], soybean oil [HB-S], olive oil [HF-O], or fish oil [HF-F]. A fifth group was put on a standard diet [SD]. Blood samples were collected after 8 weeks at non-fasting state and after a 24h fast. Body weight, food intake, and plasma parameters - glucose, insulin, DAG, and HOMA-IR, as an insulin resistance index - were measured. Body weight and food intake in the HF-S and HF-B groups were higher than in the other groups [p<0.05]. In the HF-B group the fasting insulin level and HOMA-IR were both higher as compared to the ST, HF-O or HF-F group [p<0.05]. In addition, the fasting DAG level in the HF-B group was lower than in HF-F, HF-O or ST group [p<0.05]. Finally, the HF-F group had a significantly higher DAG level than the HF-S group [P<0.05]. Diets containing polyunsaturated omega -3 and monounsaturated fatty acids cause lower weight gains and energy intakes. It is likely that these dietary fats could bring about a decrease in appetite through increasing the DAG level, thereby causing weight reduction. It is concluded, then, that they may have a role in lowering HOMA-IR or insulin level
ABSTRACT
Metabolic syndrome is a clustering of metabolic abnormalities that increase the risk of chronic diseases such as obesity, cardiovascular diseases and diabetes. This study aimed at examing the associations between dietary glycemic index [GI] and glycemic load [GL] intake using the three definition of metabolic syndrome [Mets] and each of their components. Blood samples and 24-hour dietary recalls were obtained from 120 healthy adults, without Mets or diabetes, aged >/= 40 yr, participants of the Tehran Glucose and Lipid study, in the east of Tehran. Anthropometric indices, blood pressure, fasting blood glucose, trygliceride, LDL-cholestrol and HDL-cholestrol were determined and GI and GL were measured in those who developed Mets after six years and results were compared to those subjects without Mets. Mets was defined according to criterias set by ATPIII, WHO and IDF. After adjustment for potential confounding variables, GI and GL were inversely associated with ATPIII and IDF definitions. After adjustment for confounding lifestyle and dietary factors the prevalence of Mets was significantly higher among those in the highest quintile of GI [OR: 4. 5; 95%CI: 1-19.2] and GL[OR:4.8; 95%CI;1. 1-20.6] compared to those in the lowest quintile category. On the other hand, after controlling for potential confounders, subjects in the highest quintile of GI, had higher LDL-cholestrol [P=0.005], body mass index [P=0.003] and lower HDL-cholestrol [P=0.01], than did those in the lowest quintile. Highest quintile of GL was associated with higher LDL-cholestrol [P=0.001] and lower HDL-cholestrol [P=0.015]. Results suggest that GI and GL may have unfavorable effects on metabolic syndrome and its components