Medium-Chain Triglyceride Oil and Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Trials

Abstract

Background: Dietary saturated fat raises total cholesterol and LDL cholesterol levels. It is unclear whether these effects differ by the fatty acid chain lengths of saturated fats; particularly, it is unclear whether medium-chain fatty acids increase lipid levels.

Objectives: We conducted a systematic review to determine the effects of medium-chain triglyceride (MCT) oil, consisting almost exclusively of medium-chain fatty acids (6:0-10:0), on blood lipids.

Methods: We searched Medline and Embase through March 2020 for randomized trials with a minimum 2-week intervention period that compared MCT oil with another fat or oil. Outcomes were total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride levels. Included studies were restricted to adults above 18 years of age. Studies conducted in populations receiving enteral or parenteral nutrition were excluded. Data were pooled using a random-effects meta-analysis.

Results: Seven articles were included in the meta-analysis; LDL cholesterol and HDL cholesterol were reported in 6 studies. MCT oil intake did not affect total cholesterol (0.04 mmol/L; 95% CI, -0.11 to 0.20; I2 = 33.6%), LDL cholesterol (0.02 mmol/L; 95% CI, -0.13 to 0.17; I2 = 28.7%), or HDL cholesterol (-0.01 mmol/L; 95% CI, -0.10 to 0.09; I2 = 74.1%) levels, but did increase triglycerides (0.14 mmol/L; 95% CI, 0.01-0.27; I2 = 42.8%). Subgroup analyses showed that the effects of MCT oil on total cholesterol and LDL cholesterol differed based on the fatty acid profile of the control oil (Pinteraction = 0.003 and 0.008, respectively), with MCT oil increasing total cholesterol and LDL cholesterol when compared to a comparator consisting predominantly of unsaturated fatty acids, and with some evidence for reductions when compared to longer-chain SFAs.

Conclusions: MCT oil does not affect total cholesterol, LDL cholesterol, or HDL cholesterol levels, but does cause a small increase in triglycerides.

Keywords: MCT oil; blood lipids; high-density lipoprotein; low-density lipoprotein; medium-chain fatty acids; medium-chain triglycerides; metanalysis; total cholesterol; triglycerides.