Acetylcholine is the most abundant neurotransmitter in the human body, primarily found in the hippocampus. It's integral for memory, mood, muscle control, and other nervous system and brain functions.
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If you've never heard of acetylcholine, you've likely heard of choline. Choline, found in many animal products, is the precursor to acetylcholine that's synthesized through a chemical reaction where acetic acid is esterified from acetyl-CoA and choline. Having sufficient amounts of choline is necessary for the production of acetylcholine. Adult women need 425 milligrams per day while adult men need 550 milligrams per day.
An August 2017 paper published in Nutrients examined the neuroprotective qualities of choline and found that the nutrient is essential for brain development, cognitive performance and resistance to cognitive decline associated with aging and neurodegenerative diseases. While acetylcholine cannot be ingested through dietary sources, choline is found in food sources and can be synthesized to acetylcholine in the body. Rich sources of dietary choline include:
- Egg yolks
- Green split peas
- Mung beans
Because acetylcholine is an important neurotransmitter involved in both brain function and health, low levels have been associated with neurological dysfunction. A small clinical trial published in May 2019 in BMC Neurology showed that acetylcholine may slow down the pathogenesis of Alzheimer's disease while a November 2018 study pubished in the journal of Aging Clinical and Experimental Research found that low levels of acetylcholine in elderly individuals was a contributor to postoperative delirium, marked by notable changes in consciousness, inattention and disordered thinking.
Contrastingly, a December 2015 human imaging study published in the journal of Current Opinion in Neurobiology, suggested that individuals major depressive disorder or bipolar disorder have higher levels of acetylcholine throughout multiple regions of the brain in comparison to healthy subjects.
Accumulation of acetylcholine can cause cramping, increased salivation, exessive tear production, weak muscles, paralysis, diarrhea and blurry vision. The mechanisms behind acetylcholine imbalances are not well understood and continue to be studied.
Other effects of high levels of acetylcholine have been reported after the use of acetylcholinesterase inhibitors, medications that block the breakdown of acetylcholine. In fact, a July 2016 paper published in BioMed Research International documented the use of acetylcholinesterase inhibitors as a protocol for the symptomatic treatment of Alzheimer's — showing promise for the neurotransmitter.
While eating foods rich in choline doesn't have adverse reactions, using supplements to boost acetylcholine production is not indicated nor is it safe for everyone. In fact, it may even do more harm than good when contraindications are present. All diagnosing of acetylcholine deficiency or toxicity and subsequent supplementation should only be done under the care of a qualified healthcare provider.
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- Nutrients: "Neuroprotective Actions of Dietary Choline"
- USDA Food Composition Databases: "Nutrient List, Choline"
- Aging Clinical and Experimental Research: "Postoperative Delirium in the Elderly: the Potential Neuropathogenesis"
- Current Opinion in Neurobiology: "Neuromodulation by Acetylcholine: Examples from Schizophrenia and Depression"
- BioMed Research International: "Therapies for Prevention and Treatment of Alzheimer's Disease"