Acetyl-L-Carnitine (ALC) is a protein derived from L-Carnitine, the main role of which is to transport fatty acids to the mitochondria, where they can be burned off to produce the cellular fuel ATP. L-Carnitine is both a nutrient found in meat and a compound produced by the body. Acetyl-L-Carnitine can be converted to L-Carnitine as needed and vice versa, but ALC has advantages as a supplement: it can more efficiently reach the brain, and may also be better absorbed from the gut.
One of the most effective measures that an individual can take to increase their lifespan and healthspan is to exercise. ALC can reduce muscle damage and soreness following exercise, and can also improve performance in those with reduced muscle blood flow (claudication). ALC may also aid weight loss.
ALC appears to have some neuroprotective effects: it is able to cross the blood-brain barrier and may increase the availablity of the essential neurtoransmitter acetylcholine, improve energy availability, and might even improve cognition.
ALC may also reduce blood sugar, blood pressure and inflammation, all of which are associated with the development of age-related chronic disease.
Multiple systematic review and meta-analyses of L-carnitine supplementation have shown beneficial effects with exercise, including reduced muscle damage and soreness, as well as improved exercise performance in those with reduced muscle blood flow (claudication). Another meta-analysis found that carnitine resulted in weight loss. While these meta-analyses did not include trials of acetyl-L-carnitine specifically, similar effects have been seen in randomised, placebo-controlled trials of ALC, and it is likely to share the benefits of L-carnitine.
Due to its ability to efficiently cross the blood-brain-barrier, acetyl-L-carnitine has been the subject of many trials investigating its neurological effects. ALC may increase energy availability in the brain, and animal studies show that it can boost the release of acetylcholine. Consequently, ALC may have a neuroprotective effect. ALC also appears improve cognition in elderly patients with chronic fatigue, but whether it is also able to improve cognition in younger, healthier individuals has not been studied. A systematic review and meta-analysis of 12 randomised trials also suggests that ALC may reduce depressive symptoms with fewer adverse effects than established antidepressants.
In addition to the above benefits, studies have found wide ranging positive effects including reducing blood pressure, blood sugar and inflammation, though some of these have not yet been rigorously investigated.
Acetyl-L-carnitine is likely to be safe for healthy adults. However, its safety during pregnancy or breast-feeding is unknown. It might also increase the severity of some neurological symptoms like seizures, and may interact with some anticoagulants such as warfarin.
The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials: DOI: 10.1080/07315724.2019.1661804
The Effect of (L-)carnitine on Weight Loss in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials: DOI: 10.1111/obr.12436
A systematic review and meta-analysis of propionyl-L-carnitine effects on exercise performance in patients with claudication: https://www.ncbi.nlm.nih.gov/books/NBK132409/
Acetyl L-carnitine (ALC) Treatment in Elderly Patients With Fatigue: DOI: 10.1016/j.archger.2007.03.012
Acetyl-L-carnitine Enhances Acetylcholine Release in the Striatum and Hippocampus of Awake Freely Moving Rats: DOI: 10.1016/0304-3940(89)90826-4
Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis: DOI: 10.1097/PSY.0000000000000537
Ameliorating Hypertension and Insulin Resistance in Subjects at Increased Cardiovascular Risk: Effects of acetyl-L-carnitine Therapy: DOI: 10.1161/HYPERTENSIONAHA.109.132522
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