As the name implies, acetyl-L-carnitine is an acetyl ester of L-carnitine, which is a natural molecule produced in the human body. Dietary sources of L-carnitine include animal products such as fish, meat, milk, and poultry. Both L-carnitine and acetyl-L-carnitine are also available as dietary supplements. (5) Keep reading to learn more about the health benefits of acetyl-L-carnitine and how it can improve mood, enhance energy levels, and promote weight loss.
According to scientific literature, there are many health benefits associated with acetyl-L-carnitine including:
- Enhances metabolism
- Positively influences mitochondrial function
- Provides pain-relieving effects in neuropathies
- Provides antioxidant and anti-apoptotic (cell death-preventing) activity
- Reduces neuroinflammation and neurodegeneration (12)
L-carnitine exhibits many of these properties as well but the two are very different when it comes to absorption.
Acetyl-L-carnitine vs. L-carnitine
Depending on the metabolic needs of the cell, enzymes convert L-carnitine to acetyl-L-carnitine and vice versa. The biggest differences between the two are that acetyl-L-carnitine more readily crosses the blood-brain barrier and is more easily absorbed in the gut compared to L-carnitine. (3)
Because acetyl-L-carnitine has multiple mechanisms of influence on a cellular level, its health benefits are diverse.
1. Brain function and mental health
Several double-blind controlled clinical trials have shown that acetyl-L-carnitine may have beneficial effects on Alzheimer’s disease and depression. (8) Because low levels of acetyl-L-carnitine and L-carnitine are linked to depression, a 2021 paper concluded that serum carnitine levels could be an effective biomarker for major depressive disorder. (6) A 2020 review of 37 different research papers explained that acetyl-L-carnitine can help slow cognitive decline through several mechanisms via the gut-liver-brain axis including promoting mitochondrial energy metabolism, protecting against toxin buildup in the brain, and exerting neurotrophic effects. (7)
2. Diabetic neuropathy
In 2005, an analysis of two different randomized placebo-controlled trials demonstrated that acetyl-L-carnitine was successful at alleviating symptoms of diabetic neuropathy, especially pain, compared to a placebo. In those two trials, acetyl-L-carnitine also improved nerve fiber regeneration. (10)
Because acetyl-L-carnitine impacts mitochondrial energy, it’s not surprising that it can positively influence fatigue. In fact, research demonstrates that patients with chronic fatigue syndrome have much lower levels of acetyl-L-carnitine and that when the diet is supplemented with acetyl-L-carnitine, there is a statistically significant improvement in energy levels. (1)
4. Weight loss
L-carnitine is instrumental in energy and glucose metabolism and burns fats and carbohydrates, which is why it can be a useful weight loss tool. (3) A 2016 review and meta-analysis of randomized controlled trials found that the participants who took L-carnitine lost significantly more weight and had decreased body mass index compared to the placebo group. (9)
Acetyl-L-carnitine and alpha-lipoic acid
In some cases, acetyl-L-carnitine is combined with alpha-lipoic acid to enhance efficacy. For example, a 2021 study showed that the combination of acetyl-L-carnitine and alpha-lipoic acid led to an increase in antioxidant capacity and a decrease in oxidative stress. (2) Another study showed that the combination of acetyl-L-carnitine and alpha-lipoic acid was effective at improving blood pressure and vascular function in patients with coronary artery disease compared to placebo. (4) A 2008 review concluded that the combination of acetyl-L-carnitine and alpha-lipoic acid not only had neuroprotective properties, it also enhanced cognition. (11)
The bottom line
Acetyl-L-carnitine may provide a variety of health benefits from improved mood to enhanced energy to weight loss. It is often the preferred form of L-carnitine because of its higher absorption and ability to cross the blood-brain barrier.
If you are interested in trying acetyl-L-carnitine as a dietary supplement, please discuss it with your integrative healthcare practitioner first.
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- Levy, S. H. (2018). Integrative Medicine (Fourth Edition). Science Direct. https://www.sciencedirect.com/topics/neuroscience/acetylcarnitine
- Lopez-Maldonado, A., Pastoriza, S., & Rufian-Henares, J. A. (2021). Assessing the antioxidant and metabolic effect of an alpha-lipoic acid and acetyl-L-carnitine nutraceutical. Current Research in Food Science, 4, 336-344.
- Mendelson, S. D. (2008). Metabolic syndrome and psychiatric illness. Science Direct.
- McMackin, C. J., Widlansky, M. E., Hamburg, N. M., Huang, A. L., Weller, S., Holbrook, M., Gokce, N., Hagen, T. M., Keaney, J. F., & Vita, J. A. (2007). Effect of combined treatment with alpha lipoic acid and acetyl-L-carnitine on vascular function and blood pressure in coronary artery disease patients. J Clin Hypertens, 9(4), 249-255.
- National Institutes of Health. (2021, March 19). Carnitine: fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/
- Nie, L, Liang, J, Shan, F., Wang, B., Mu, Y., Zhou, X, & Xia, Q. (2021). Carnitine and acetyl-L-carnitine: potential novel biomarkers for major depressive disorder. Front Psychiatry, 12.
- Pennisi, M., Lanza, G., Cantone, M., D’Amico, E., Fisicaro, F., Puglisi, V., Vinciguerra, L., Bella, R., Vicari, E., & Malaguarnera, G. (2020). Acetyl-L-carnitine in dementia and other cognitive disorders: a critical update. Nutrients, 13, 1389.
- Pettegrew, J. W., Levine, J., & McClure, R. J. (2000). Acetyl-L-carnitine physical-chemical, metabolic, and therapeutic properties: relevance for its mode of action in Alzheimer’s disease and geriatric depression. Molecular Psychiatry, 5, 616-632.
- Pooyandjoo, M., Nouhi, M., Shab-Bidar, S., Djafarian, K., & Olyaeemanesh, A. (2016). Effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials. Obes Rev, 17(10), 970-6.
- Sima, A., Calvani, M., Mehra, M., & Amato, A. (2005). Acetyl-L-carnitine improves pain, nerve regeneration and vibratory perception in patients with chronic diabetic neuropathy. Diabetes Care, 28(1), 89-94.
- Soczynska, J. K., Kennedy, S. H., Chow, C., Woldeyohannes, H. O., Konarski, J. Z., & McIntyre, R. S. (2008). Acetyl-L-carnitine and alpha lipoic acid: possible neurotherapeutic agents for mood disorders. Expert Opinion on Investigational Drugs, 17(6), 827-843.
- Traina, G. (2016). The neurobiology of acetyl-L-carnitine. Frontiers in Bioscience-Landmark, 21(7), 1314-1329.