A comparison of fish oil or corn oil supplements in hyperlipidemic subjects with NIDDM

To examine the effects on blood lipids and glycemic control of fish oil and corn oil supplementation at two levels in subjects with hyperlipidemia and non-insulin-dependent diabetes mellitus (NIDDM).

Forty subjects (18 men and 22 women; aged 53.9 +/- 7.0 years) with NIDDM and hyperlipidemia were randomly assigned to one of four treatment groups: 9 g of fish oil, 18 g of fish oil, 9 g of corn oil, or 18 g of corn oil daily supplementation for 12 weeks.

The level of oil supplements (9 g compared with 18 g) did not have a significant effect within each oil group on glycemic control and lipids. Significant differences (P < 0.05) in lipids were found when the 9-g and 18-g groups were combined. In subjects consuming fish oil, plasma very-low-density lipoprotein (VLDL) cholesterol (P = 0.0001), plasma triglyceride (TG) (P = 0.0001), and plasma VLDL TGs (P = 0.02 at 6 weeks and P = 0.0001 at 12 weeks) were significantly lowered compared with subjects consuming corn oil. Plasma VLDL cholesterol increased across time in the corn oil group (P = 0.04). Plasma low-density lipoprotein (LDL) cholesterol was temporarily increased (P = 0.008) in the fish oil group at 6 weeks, but the effect was no longer present at 12 weeks. No significant differences between fish oil- or corn oil-supplemented diets were found in total plasma cholesterol, high-density lipoprotein cholesterol, fasting plasma glucose, glycosylated HbA1c, weight, and blood pressure.

In this study, fish oil supplementation improved plasma VLDL cholesterol, VLDL TGs, and total TGs while having a transient deterioration in LDL cholesterol in subjects with NIDDM. Furthermore, fish oil supplementation had no significant deleterious effect on glycemic control.