"A meta-analysis of 12 studies suggests that the nutrient acetyl-l-carnitine (ALC), when taken as a nutritional supplement, has antidepressant effects. The meta-analysis by researcher Nicola Veronese and colleagues appeared in the journal Psychosomatic Medicine in 2017. Veronese and colleagues found that in nine randomized controlled trials, ALC reduced depressive symptoms significantly compared to placebo. In three randomized controlled trials that compared ALC with established antidepressants, ALC showed similar effectiveness at reducing depressive symptoms while producing 79% fewer side effects. Doses of ALC ranged from 1 to 4 grams per day, and higher doses led to greater improvement.In the comparisons with antidepressants, the other treatments included fluoxetine (Prozac), duloxetine (Cymbalta), and amisulpride (which is not approved by the US Food and Drug Administration).Low ALC has been linked to depression. According to Veronese and colleagues, ALC deficiency can dysregulate the transport of fatty acids across the inner membrane of mitochondria. The researchers suggest several ways that ALC might contribute to an improvement in depression. One is that is seems to promote neuroplasticity in cerebral regions implicated in depression, such as the hippocampus. It could also work by increasing brain-derived neurotrophic factor (BDNF), which protects neurons and is important for learning and memory. ALC decreases release of the neurotransmitter glutamate by increasing the production of the inhibitory metabotrophic glutamate receptor (mGluR-2) on presynaptic glutamate neurons . Another way ALC might work is by normalizing lipid metabolism. Or it could modulate neurotransmitters, increasing serotonin and dopamine and protecting against stress.In the meta-analysis, ALC produced more improvement in older patients than in younger ones. The researchers stressed the need for better treatments for older people, which may experience falls, cardiovascular disease, or increased mortality from antidepressants.ALC also seems to improve pain syndromes, making it a good option for patients with both depression and pain symptoms.Veronese and colleagues cited another meta-analysis that found that taking ALC in addition to an antidepressant led to lower rates of adverse events than the antidepressants alone, which helped patients adhere to their drug regimen.