L-Carnitine Supplementation Increases Trimethylamine-N-Oxide but not Markers of Atherosclerosis in Healthy Aged Women.
Level 4 - case-series / case-control
Uncontrolled prospective before-after interventional study without a reported randomized control group
PubMed 30485835 · doi:10.1159/000495037
What was done
Healthy older women underwent a 24-week oral L-carnitine supplementation protocol. Fasting venous blood samples were collected at baseline, mid-point, and at completion (24 weeks). Plasma free L-carnitine and trimethylamine N-oxide (TMAO) concentrations were measured via UPLC-MS/MS. Serum inflammatory and endothelial adhesion markers (C-reactive protein, IL-6, TNF-alpha, L-selectin, P-selectin, VCAM-1, ICAM-1) and lipid panels (total cholesterol, HDL-C, LDL-C, triglycerides) were analyzed using enzyme immunoassays and standard automated analyzers.
What was found
Oral L-carnitine supplementation elevated fasting plasma carnitine by the mid-point, remaining elevated through week 24. Supplementation induced a tenfold increase in plasma TMAO concentration. Despite this increase, no changes were observed in serum C-reactive protein, IL-6, TNF-alpha, L-selectin, P-selectin, VCAM-1, ICAM-1, or any measured lipid profile markers. Exact numerical values and statistical test metrics were not reported in the abstract.
Why it matters
Although TMAO is hypothesized to promote atherosclerosis following dietary carnitine metabolism, this study demonstrates that a sustained, tenfold rise in TMAO over 6 months failed to induce inflammatory, endothelial, or lipid markers of vascular disease in healthy older women.
Limits
The abstract does not disclose the sample size (n), carnitine dosage, or whether a placebo control group was included. Assessment was limited to circulating biomarkers without direct arterial imaging or cardiovascular clinical outcomes. Findings in healthy aged women may not generalize to men, younger cohorts, or populations with established cardiovascular disease.
Cited by
- supports Oral L-carnitine has low absorption bioavailability and oral supplementation increases trimethylamine N-oxide (TMAO).