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.
Bibliographical noteFunding Information:
The authors would like to thank Yi Liu for her assistance with the statistical analyses, Julia Richardson for editorial assistance with the manuscript, the staff of the Clinical Research Center for their help with data collection, and the study participants for their time and dedication to being a part of the study. This study was funded by an unrestricted gift from Cognis Corporatio n (Monheim, Germany, and Cincinnati, Ohio), the National Center for Research Resources ( UL1RR025755 ), the Clinical Research Center at The Ohio State University (grant M01-RR00034 from the NIH), and the NIH ( R21 AT003520-03S1 ). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center For Research Resources or the National Institutes of Health. Funding organizations were not involved in the study design, data collection and analysis, or manuscript preparation.
- Conjugated linoleic acid
- N-6 PUFA
- Safflower oil
- Type 2 diabetes