Review Comparison of serum acylcarnitine levels in patients with [ME/CFS] and healthy controls: a systematic review and meta-analysis, 2023, Jinushi et al.

Abstract
Background

Myalgic encephalomyelitis/chronic fatigue syndrome/systemic exertion intolerance disease (ME/CFS/SEID) is a condition diagnosed primarily based on clinical symptoms, including prolonged fatigue and post-exertional malaise; however, there is no specific test for the disease. Additionally, diagnosis can be challenging since healthcare professionals may lack sufficient knowledge about the disease. Prior studies have shown that patients with ME/CFS/SEID have low serum acylcarnitine levels, which may serve as a surrogate test for patients suspected of having this disease. This systematic review and meta-analysis aimed to investigate the differences in serum acylcarnitine levels between patients with ME/CFS/SEID and healthy controls.

Methods
This systematic review was conducted using PubMed and Ichushi-Web databases. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, we included all studies from the databases’ inception until February 17, 2023, that evaluated blood tests in both patients with ME/CFS/SEID and healthy control groups. The primary endpoint was the difference in serum acylcarnitine levels between the two groups.

Results
The electronic search identified 276 studies. Among them, seven met the eligibility criteria. The serum acylcarnitine levels were analyzed in 403 patients with ME/CFS/SEID. The patient group had significantly lower serum acylcarnitine levels when compared with the control group, and the statistical heterogeneity was high.

Conclusion
The patient group had significantly lower serum acylcarnitine levels when compared with the control group. In the future, the measurement of serum acylcarnitine levels, in addition to clinical symptoms, may prove to be a valuable diagnostic tool for this condition.

https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-023-04226-z

 

I benefitted from taking ALCAR and lipoic acid years ago but needed to take a break from it b/c it made my brain energy over active.

I might go back on it to see if it has the same effect.

 

At one point, fatty acids (palmitic?) in meat made my ME symptoms worse, unless I took some supplemental carnitine with it. After a few months, I no longer needed the supplement. I never noticed any other effect of extra carnitine.

 

For total and free carnitine levels there was mostly no difference. For free acylcarnitine they have this overview of 7 studies, if possible split up between males and females:

 

Some background on the authors:

"In the course of researching mental health problems post-COVID-19, we realized that many patients have psychiatric disorders such as depression and anxiety due to incorrect diagnosis and treatment of ME/CFS/SEID, which led us to this systematic review, in the hope of helping to solve these problems."

"After a thorough review of the literature on ME, CFS, and SEID reported to date, we hypothesize that low serum acylcarnitine levels in patients with ME/CFS/ SEID may be due to an impaired mitochondrial fatty acid oxidation cascade caused by viral infections, including COVID-19 [24, 25]. Normally, in the mitochondrial matrix, fatty acids taken up by cells undergo β-oxidation to produce ATP. In addition, long-chain fatty acids are converted to acyl-CoA in cells, which reacts with carnitine to produce acylcarnitine [26]. Carnitine is an essential factor in the aforementioned cascade"​

 

That rings true, L-Carnitine-Tartrate, (subjectively most strengthening imho) taken as needed, has rescued me from crashes on innumerable occasions.

Have my doubts about using blood acylcarnitine level as a diagnostic tool but would bet it could usefully inform supplementation therapy choices.