Time-dependent effects of safflower oil to improve glycemia, inflammation and blood lipids in obese, post-menopausal women with type 2 diabetes: a randomized, double-masked, crossover study

Abstract

Background & aims: Metabolic effects of dietary fat quality in people with type 2 diabetes are not well-understood. The study objective was to evaluate effects of conjugated linoleic acid (CLA) and safflower (SAF) oils on glycemia, blood lipids, and inflammation. The hypothesis we tested is that dietary oils improve glycemia, lipids, and inflammatory markers in a time-dependent way that follows accumulation of linoleic acid and CLA isomers in serum of subjects supplemented with dietary oils.

Methods: Fifty-five post-menopausal, obese women with type 2 diabetes enrolled, and 35 completed this randomized, double-masked crossover study. Treatments were 8 g daily of CLA and SAF for 16 weeks each. We used a multiple testing procedure with pre-determined steps analysis to determine the earliest time that a significant effect was detected.

Results: CLA did not alter measured metabolic parameters. SAF decreased HbA1c (-0.64 ± 0.18%, p = 0.0007) and C-reactive protein (-13.6 ± 8.2 mg/L, p = 0.0472), increased QUICKI (0.0077 ± 0.0035, p = 0.0146) with a minimum time to effect observed 16 weeks after treatment. SAF increased HDL cholesterol (0.12 ± 0.05 mmol/L, p = 0.0228) with the minimum time to detect an effect of SAF at 12 weeks. The minimum time to detect an increase of c9t11-CLA, t10c12-CLA, and linoleic acid in serum of women supplemented CLA or SAF, respectively, was four weeks.

Conclusions: We conclude that 8 g of SAF daily improved glycemia, inflammation, and blood lipids, indicating that small changes in dietary fat quality may augment diabetes treatments to improve risk factors for diabetes-related complications.