L-carnitine is a naturally occurring compound that plays a key role in energy production in the body.
Some research suggests it may enhance cognitive function, but does it really work as a nootropic or “smart drug” in healthy people?
Key Facts:
- L-carnitine is made in the body and obtained from food sources like meat. It helps transport fatty acids into mitochondria to produce cellular energy.
- Some studies show L-carnitine improves cognition in people with cognitive impairment. It’s theorized it may work by enhancing acetylcholine levels and energy production in the brain.
- Only 2 small studies have looked at L-carnitine for cognitive enhancement in healthy people. Both found no significant benefit for reaction time, attention, memory or other measures.
- More research is needed on larger samples over longer periods to determine if L-carnitine has any nootropic effects in normal healthy individuals.
What is L-Carnitine and How Might it Enhance Cognition?
L-carnitine is a naturally occurring compound that plays an essential role in energy metabolism.
It transports long-chain fatty acids into mitochondria, where they can be oxidized to produce ATP, the cell’s energy currency.
The human body can produce L-carnitine from the amino acids lysine and methionine.
It can also be obtained from food sources like red meat, fish, poultry, dairy products and some plant foods.
L-carnitine is concentrated in tissues that use a lot of energy, like skeletal and cardiac muscle.
It also readily crosses the blood-brain barrier and is present at high levels in the brain.
Research shows L-carnitine administration can improve cognitive function in some conditions associated with cognitive decline, including Alzheimer’s disease, hepatic encephalopathy, alcoholism and Parkinson’s.
It’s thought L-carnitine may enhance cognition through several mechanisms:
- Increasing energy production in the brain
- Promoting acetylcholine synthesis
- Reducing oxidative stress
- Improving neuron health and function
Acetylcholine is a neurotransmitter involved in learning, memory and attention.
Oxidative stress can damage neurons and impair signalling.
By counteracting these processes, L-carnitine may theoretically prevent or slow cognitive decline.
This has led to interest in L-carnitine as a nootropic or cognitive enhancer – a supplement taken to boost brainpower in normal healthy individuals.
But does it really work for this purpose?
The Evidence for L-Carnitine as a Cognitive Enhancer
To evaluate the potential of L-carnitine as a nootropic supplement, researchers in China conducted a systematic review of studies on L-carnitine for cognitive enhancement in people without cognitive impairment.
The 2016 review only found 2 small trials that met the inclusion criteria:
- A study on 400 healthy young women tested the effects of L-carnitine versus placebo over 3 days.
- Another small crossover trial examined a single dose of L-carnitine on cognitive performance in 18 healthy young adults.
In both studies, there was no significant difference between L-carnitine supplementation and placebo for any cognitive measure.
These included reaction time, attention, short-term memory and other domains.
The women’s study also found no difference in minor side effects between the L-carnitine and placebo groups.
The single-dose trial did not report on adverse effects.
Limitations and Need for Further Study
The researchers concluded there is currently very little evidence L-carnitine enhances cognition in healthy individuals.
However, they note several limitations of the data:
- Only 2 very small trials were available, with short treatment duration.
- Trial methods and reporting quality were suboptimal.
- Wide confidence intervals mean the true effect remains uncertain.
- Differences in tests and outcomes limited data synthesis.
- Publication bias cannot be excluded.
They stress the need for larger, better-designed trials with longer treatment and follow-up periods to properly evaluate the nootropic potential of L-carnitine supplements in people without cognitive impairment.
Other Cognitive Enhancer Candidates Being Investigated
While L-carnitine’s effects are still inconclusive, research continues on other compounds that may enhance cognition in healthy individuals:
Omega-3 fatty acids: Found in fish, omega-3s may boost brain cell health, neuroplasticity, blood flow and neuron signalling. Studies are mixed but suggest possible small benefits for attention, processing speed and executive function.
Caffeine: Aside from the well-known stimulant effect, caffeine influences neurotransmitters and may enhance vigilance, alertness, reaction time and memory consolidation. But effects are modest and tolerance can develop.
Bacopa monnieri: Traditionally used in Ayurvedic medicine, this herb contains antioxidants that may protect brain cells from damage. Some evidence it can improve memory and processing speed.
Ginkgo biloba: Ginkgo is theorized to increase blood circulation and neuron health in the brain. Reviews conclude it may provide a small benefit for memory and executive function.
While these supplements generally appear safe, their cognitive benefits are typically small or inconsistent.
More research is underway, but no particular nootropic seems stand out as highly effective yet.
What to know about L-carnitine…
- L-carnitine plays an important role in cellular energy metabolism and is present at high levels in the brain.
- In theory, L-carnitine could enhance cognition by improving energy supply, acetylcholine synthesis, and neuron health in the brain.
- Studies show potential benefit for L-carnitine in cognitive disorders, but evidence in normal healthy people is still scarce.
- Only two small, short-term trials have examined L-carnitine’s effects on cognition in the healthy, and neither found benefits compared to placebo.
- Larger, longer trials of L-carnitine are needed to know if it has any nootropic effects in people without cognitive deficits.
- Research continues on other supplements like omega-3s, caffeine, bacopa and ginkgo biloba as cognitive enhancers, but evidence is still limited.
The Bottom Line: L-carnitine for cognition
While L-carnitine is important for energy metabolism in the body and brain, there is currently very little evidence from human trials that it enhances cognitive function in healthy people.
More research is needed to determine if L-carnitine has any benefits as a nootropic supplement.
Given the lack of proven effects on cognition, healthy individuals looking to optimize brain performance may want to focus on lifestyle strategies like getting enough sleep, exercise and mental stimulation rather than unproven supplements.
But future research could change the outlook for nootropic candidates like L-carnitine.
References
- Study: L-carnitine for cognitive enhancement in people without cognitive impairment
- Authors: Ning Chen et al. (2017)
