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Muscles do not contract of their own accord; they rely on messages from the brain via nerves to excite them so that they contract. Physiologists Cohen and Wurtman (1975)[1] believe Choline has a vital role in transmitting the message from the nerve ending to the muscle.

What is the function of Choline?

Choline is a vitamin-like compound that is an essential part of the human diet and is used by the body to produce acetylcholine. Without choline, acetylcholine cannot be produced, and the body cannot function normally. Choline is essential for the process of breaking down fat for energy.

How do nerves tell muscles to contract?

A signal is transmitted from the brain to the end of the nerve attached to the muscle that it wishes to contract. There is a small space between the end of the nerve and the muscle, and it is across this neuromuscular space that the nerve pushes small quantities of a chemical called acetylcholine. When sufficient acetylcholine attaches to the muscle cell's outer surface, the muscle cell contracts. Should you run out of acetylcholine, the muscles will not be able to contract, even if they are adequately stocked with energy (ATP).

Physiologists Cohen and Wurtman (1975)[1], reckon that acetylcholine is broken down inside the neuromuscular junctions during prolonged exercise. Nerve cells collect the choline floating in the blood to make new acetylcholine, and consequently, your blood choline levels start decreasing. If your choline levels fall too far, acetylcholine production cannot continue, and your nerve cells will refuse to stimulate your muscles.

Choline and the 'Wall'

The choline concentrations remain sufficient when you compete in a 5km, 10km or half-marathon. Your choline levels drop dramatically only when you exercise continuously for approximately two hours or more. Some exercise scientists believe that this drop-in Choline is behind the devastating fatigue that strikes near the end of a marathon - referred to, by many marathon runners, as the 'Wall'.

Some scientists reason that choline supplements, if taken at the right time and in the right amount, might help the nervous system stimulate muscle cells and keep you striving toward the marathon finish line at your desired pace.

Where does choline come from?

Choline is available in beetroot, liver, cauliflower, soybeans, spinach, lettuce, nuts, and eggs. A choline-rich natural diet may not prevent the drop-in blood choline levels after 20 miles or so of marathon running.

For a marathon, how much and when?

An appropriate amount is about 2.5grms, swallowed about an hour before your marathon begins. This additional dosage of choline in your blood may start to fall three hours after takeing it (e.g. two hours into your marathon), so it perhaps makes sense to take another 2.5-gram dose at the 10 to 13-mile point of your race.

Are there any side effects?

Choline is safe to take, but some side effects may make you unpopular. These include diarrhoea or foul flatulence.


  1. COHEN, E.L. and WURTMAN, R.J. (1975) Brain acetylcholine: Increase after systematic choline administration. Life Sciences, 16 (7), p. 1095-1102

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • MACKENZIE, B. (2000) Choline [WWW] Available from: [Accessed