Objective: We investigated the effects of dietary intervention with canola or olive oil in comparison with commonly used refined oil in Asian Indians with nonalcoholic fatty liver disease (NAFLD).
Subjects and methods: This was a 6-month intervention study including 93 males with NAFLD, matched for age and body mass index (BMI). Subjects were randomized into three groups to receive olive oil (n=30), canola oil (n=33), and commonly used soyabean/safflower oil (control; n=30) as cooking medium (not exceeding 20 g/day) along with counseling for therapeutic lifestyle changes. The BMI, fasting blood glucose (FBG) and insulin levels, lipids, homeostasis model of assessment for insulin resistance (HOMA-IR), HOMA denoting β-cell function (HOMA-βCF), and disposition index (DI) were measured at pre- and post-intervention. Data were analyzed with one-way analysis of variance (ANOVA) and Tukey's Honestly Significant Difference multiple comparison test procedures.
Results: Olive oil intervention led to a significant decrease in weight and BMI (ANOVA, P=0.01) compared with the control oil group. In a comparison of olive and canola oil, a significant decrease in fasting insulin level, HOMA-IR, HOMA-βCF, and DI (P<0.001) was observed in the olive oil group. Pre- and post-intervention analysis revealed a significant increase in high-density lipoprotein level (P=0.004) in the olive oil group and a significant decrease in FBG (P=0.03) and triglyceride (P=0.02) levels in the canola oil group. The pre- and post-intervention difference in liver span was significant only in the olive (1.14 ± 2 cm; P<0.05) and canola (0.66 ± 0.33 cm; P<0.05) oil groups. In the olive and canola oil groups, post-intervention grading of fatty liver was reduced significantly (grade I, from 73.3% to 23.3% and from 60.5% to 20%, respectively [P<0.01]; grade II, from 20% to 10% and from 33.4% to 3.3%, respectively [P<0.01]; and grade III, from 6.7% to none and from 6.1% to none, respectively). In contrast, in the control oil group no significant change was observed.
Conclusions: Results suggest significant improvements in grading of fatty liver, liver span, measures of insulin resistance, and lipids with use of canola and olive oil compared with control oils in Asian Indians with NAFLD.