The popular supplement acetyl l-carnitine made new headlines recently with a Stanford-led study connecting low levels of this nutrient with symptoms of clinical depression. Previous research with animals had made this connection, and also showed supplementing with the nutrient improved symptoms within days. This study is the first to show this association in humans, with the lowest levels of acetyl l-carnitine seen in the most depressed patients.(1)
While administering acetyl l-carnitine improved symptoms in animals, controlled trials in humans have not been conducted yet, so it is too soon to tell if the benefits could translate. However, this study is an important first step in understanding another piece of the biochemical puzzle for depression, especially for the significant group of patients who do not respond to current drug therapies. Its potential fast-acting effect also has hopeful implications, as many of these drugs can take weeks to reach therapeutic levels.
What Does Acetyl L-Carnitine Do?
L-carnitine transports fatty acids for energy to mitochondria in the cells throughout your body. The acetyl form appears to be the most effective form for the brain, where it also plays a protective role by preventing the overactivity of excitatory nerve cells in the frontal cortex and hippocampus.(1) Because of its crucial role in energy transport, it is understandable how negative symptoms could arise from low levels.
Your body can make acetyl l-carnitine from the amino acid lysine and methionine but genetic and other factors can affect its production, such as illness, vitamin C status or a strict vegan or vegetarian diet.(2) Blood levels of acetyl l-carnitine naturally decline with age as well. For this reason, it may be useful to supplement to help protect the brain and maintain cognitive health as we age.
Acetyl L-Carnitine and Overall Health
Depression is not the only area of interest for researchers regarding the potential uses of acetyl l-carnitine. Studies have investigated the possible role of acetyl l-carnitine for numerous health issues such as cognitive impairment, nerve pain, male fertility, chronic fatigue and much more. Because of its role in energy production and its neuroprotective properties, there is much potential to be helpful for a number of health concerns. Some of this research has proved inconclusive, in particular as a weight loss aid, but here are a few of the positive highlights:
- A 52-week study with over 1200 participants showed significant improvement in neuropathic pain symptoms associated with diabetes. Participants took 1000 mg daily.(3)
- A small study of 30 participants with mild dementia showed cognitive improvement at 2000 mg daily versus a placebo.(4)
- Several studies show acetyl l-carnitine is useful for general age related cognitive decline. One such clinical trial showed benefit after 45 days at 1500 mg daily, and the effects lasted an additional 30 days after supplementation ended. Participants showed improvement in memory, mood, and stress response.(6)
- A double-clinical trial using acetyl l-carnitine 2000 mg twice a day for three months showed that cirrhosis patients may see benefits in energy, cognitive, and neurological function. More studies are needed to investigate these possible benefits further.
- Acetyl L-Carnitine outperformed the drug amantadine in a small study with multiple sclerosis patients experiencing fatigue. Participants saw significantly more improvement in fatigue symptoms with 1000 mg acetyl l-carnitine twice daily vs 100 mg amantadine twice daily.(5)
In addition to these more specifically studied uses, acetyl l-carnitine is frequently used in sports and fitness to aid in muscle stamina and recovery. Besides its general role in fatty acid transport and energy for mitochondria, acetyl l-carnitine may play a role in delaying lactic acid buildup and the onset of muscle fatigue. Many athletes use it pre and or post-workout.
Using Acetyl L-Carnitine
Because acetyl l-carnitine can be produced by the body in healthy individuals, there is no suggested minimum daily intake as a supplement. However, in numerous studies, it has been taken safely with little or no side effects in dosages as high as 3000 mg daily. Those with hypothyroid conditions may want to avoid taking the supplement, as some evidence suggests it may interfere with thyroid medications. Those with seizure disorders should avoid acetyl l-carnitine as well. In excessive doses, stomach upset, sleeplessness, dry mouth and other side effects could occur. As with any supplement, it is always best to follow the dosage and serving guidelines on the label. Acetyl l-carnitine is often recommended to be taken in the morning or in divided doses in the morning and midday for best results. It may be too energy stimulating for some when taken at night.
The best advice for trying acetyl l-carnitine is to consult with a health practitioner who is familiar with its proper use and dosage. They may tailor a program including other complimentary supplements that best fit your specific needs. As always, choosing a professional quality, pure acetyl l-carnitine supplement is crucial as well.
There is a spectrum of quality of raw materials in the vitamin industry, so if a brand is significantly cheaper than others, it may be because they are using less potent ingredients from less reputable suppliers. This is an important point, both for product safety, but also to ensure the product is effective. This is especially true for cognitive supplements. Professional brands used by practitioners pay special attention to ingredient source for this reason.
References 1 Rasgon, Natalie. “Study links depression to low blood levels of acetyl l-carnitine”. July 30th, 2018. 2 Mawer, Rudy. “L-Carnitine- A review of benefits, side effects and dosage”. Aug. 20th, 2016. 3 Sima, AA et al. “Acetyl L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy”. Diabetes Care. Jan. 28th, 2005. 4 Passeri M, et al. “Acetyl l-carnitine in the treatment of mildly demented elderly patients”. Int. J Clin Pharm Res. 1990: 10:1-2. 75-9 5 Tomassini V, et al. “Comparison of the effects of acetyl L-carnitine and amantadine for the treatment of fatigue in multiple sclerosis:”. J Neurol Sci. Mar. 15, 2004. [/su_note] 6 https://www.uofmhealth.org/health-library/hn-2795007 Published on Web May 24th, 2015.
