Fish oil and olive oil can modify insulin resistance and plasma desacyl-ghrelin in rats.

Background: Evidence exists for reciprocal effects of insulin and desacyl-ghrelin (DAG) concentration, but the association between different fatty acid saturation in high fat diet (HFD) and these hormones remain to be established. To evaluate the impact of different sources of dietary fat and the level of fatty acid saturation on plasma insulin and DAG levels and also the association of DAG with insulin action this study was carried out.

Methods: Male weaning Wistar rats were randomly divided into four groups of HFDs, high fat butter (HF-B), high fat soy (HF-S), high fat olive (HF-O), high fat fish (HF-F), and a group of standard diet (SD). Blood samples were collected after 8 weeks and after they were fasted for 24 h. Body weight, food intake, plasma glucose, insulin, DAG and insulin resistance (HOMA-IR) were measured.

Results: Plasma insulin levels at fed and fasted status, were significantly higher in rats on HF-B compared to those on SD, HF-F and HF-O diets (P<0.05). Insulin concentration in rats on HF-S was also higher than those on SD, HF-F and HF-O diets (P<0.05), in the feeding status. Insulin resistance was significantly higher in rats on HF-B, compared to those on SD, HF-F and HF-O (P<0.05). Rats that were fed with HF-B diet had lower fasting plasma DAG levels than the SD, HF-F and HF-O groups (P<0.05); furthermore, the HF-F group had significantly higher DAG level than the HF-S groups (P<0.05).

Conclusions: Fish and olive oils may hence contribute to lower insulin level and HOMA-IR by increasing DAG concentration and may have more health benefits than other fat sources in diets.