Choline is associated with the vitamin B complex; it is not an officially recognised vitamin. Choline is a component of phosphatidylcholine and an active constituent of dietary lecithin, but the two substances are not synonymous.
Choline is an essential nutrient for several mammalian organisms, but there is no agreement over its essentiality as a vitamin for humans. However, the US Food and Nutrition Board of the National Institute of Medicine has established a Dietary Reference Intake for adults of 550 mg a day for men and 425 mg a day for women, with lower amounts for children, together with an upper intake level of 3.5 g daily for adults over 18 years.
Estimated dietary intake in the UK is 250– 500 mg daily. Choline can also be synthesised in the body from phosphatidylethanolamine.
Choline serves as a source of labile methyl groups for transmethylation reactions. It functions as a component of other molecules such as the neurotransmitter acetylcholine, phosphatidylcholine (lecithin) and sphingomyelin, structural constituents of cell membranes and plasma lipoproteins, platelet activating factor and plasmalogen (a phospholipid found in highest concentrations in cardiac muscle membranes).
Lecithin and sphingomyelin participate in signal transduction, an essential process for cell growth, regulation and function. Animal studies suggest that choline or lecithin deficiency may interfere with this critical process and that alterations in signal transduction may lead to abnormalities such as cancer and Alzheimer’s disease.
Choline is widely distributed in foods (mainly in the form of lecithin). The richest sources of choline are brewer’s yeast, egg yolk, liver, wheatgerm, soya beans, kidney and brain. Oats, peanuts, beans and cauliflower contain signifi-cant amounts.
Some choline is absorbed intact, probably by a carrier-mediated mechanism; some is metabolised by the gastrointestinal flora to trimethylamine (which produces a fishy odour).
Choline is stored in the brain, kidney and liver, primarily as phosphatidylcholine (lecithin) and sphingomyelin.
Elimination of choline occurs mainly via the urine.
Dietary choline deficiency occurs in animals, and abnormal liver function, liver cirrhosis and fatty liver may be associated with choline deficiency in humans. Observations in patients on total parenteral nutrition (TPN) have shown a choline-deficient diet to result in fatty infiltration of the liver, hepatocellular damage and liver dysfunction.
As a precursor of acetylcholine, it has been suggested that choline could increase the concentration of acetylcholine in the brain. It has been suggested, therefore, that choline could be beneficial in patients with disease related to impaired cholinergic transmission (e.g. tardive dyskinesia, Huntington’s chorea, Alzheimer’s disease, Gilles de la Tourette, mania, memory impairment and ataxia). However, experimental evidence suggests that oral choline has no effect on choline metabolites in the brain.
Comparison of studies involving choline is often complicated by lack of standardisation of doses used. However, clinical trials with tardive dyskinesia patients using choline have met with some success.
Choline has also been suggested to improve performance in athletes. This idea arose because of findings that plasma choline concentrations were reduced in trained runners and athletes after sporting events. However, a double-blind crossover study in 20 cyclists showed that choline supplementation did not delay fatigue during brief or prolonged exercise.
Claims have been made for the value of choline in the prevention of CVD, including angina, atherosclerosis, hypertension, stroke and thrombosis. However, scientific evidence for these claims from RCTs is lacking. Interest has recently focused on the potential for choline (as a precursor of betaine) to reduce plasma homocysteine. One crossover study showed that phosphatidylcholine supplementation (2.6 g choline daily for 2 weeks) lowers fasting as well as post-methionine-loading plasma homocysteine concentrations in healthy men with mildly elevated homocysteine concentrations. Choline (in conjunction with carnitine) supplementation has also been shown to lower lipid peroxidation and promote conservation of antioxidants (e.g. retinol and alpha-tocopherol) in women.
Choline has also been claimed to prevent and/or treat Alzheimer’s disease, senile dementia and memory loss. A Cochrane review of 14 studies found some evidence that cytidine-diphosphocholine (CDP-choline) has a positive effect on memory and behaviour at least in the short to medium term, but evidence is limited by the quality of the studies.
No problems have been reported.
Pregnancy and breast-feeding
No problems have been reported.
Fishy odour; more severe symptoms relate to excessive cholinergic transmission (doses of 10 g daily or more) and include diarrhoea, nausea, dizziness, sweating, salivation, depression and a longer P-R interval in electrocardiograms.
Choline is available in the form of tablets and capsules.
The dose is not established. Dietary supplements generally provide 250–500 mg per dose (choline chloride provides 80% choline and choline tartrate 50% choline).
Research on choline supplementation is limited and studies are generally very poorly controlled. The limited research shows that choline does not appear to improve athletic performance. Very preliminary evidence suggests choline might be beneficial in poor memory and tardive dyskinesia, but evidence is not sufficient to recommend supplementation.
Dietary Supplements, Third Edition, by Pamela Mason, BSc, MSc, PhD, MRPharmS, published by Pharmaceutical Press, London, 2007.
Canty DJ, Zeisel SH. Lecithin and choline in human health and disease. Nutr Rev 1994; 52: 327–339.
Sheard NF, Tayek JA, Bistrian BR, Blackburn GL, Zeisel SH. Plasma choline concentration in humans fed parenterally. Am J Clin Nutr 1986; 43: 219–224.
Zeisel SH, DaCosta KA, Franklin PD. Choline, an essential nutrient for humans. FASEB J 1991; 5: 2093–2098.
Davis KL, Berger PA, Hollister LE. Choline for tardive dyskinesia. N Engl J Med 1975; 293: 152–153.
Gelenberg AJ, Doller-Wojcik JC, Growdon JH. Choline and lecithin in the treatment of tardive dyskinesia: preliminary results from a pilot study. Am J Psychiatr 1979; 136: 772–776.
Growdon JH, Hirsch MJ, Wurtman RJ, Wiener W. Oral choline administration to patients with tardive dyskinesia. N Engl J Med 1977; 297: 524–527.
Tamminga CA, Smith RC, Erickson SE, et al. Cholinergic influences in tardive dyskinesia. Am J Psychiatr 1977; 134: 769–774.
Conlay LA, Saboujian LA, Wurtman RJ. Exercise and neuromodulators: choline and acetylcholine in marathon runners. Int J Sports Med 1992; 13: S141–142.
Von Allworden HN, Horn S, Kahl J, et al. The influence of lecithin on plasma choline concentra-tions in triathletes and adolescent runners during exercise. Eur J Appl Physiol 1993; 67: 87–91.
Spector SA, Jackman MR, Sabounjian LA, et al. Effect of choline supplementation on fatigue in trained cyclists. Med Sci Sports Exerc 1995; 27: 668–673.
Olthof MR, Brink EJ, Katan MB, Verhoef P. Choline supplemented as phosphatidylcholine decreases fast-ing and postmethionine-loading plasma homocys-teine concentrations in healthy men. Am J Clin Nutr 2005; 82: 111–117.
Sachan DS, Hongu N, Johnsen M. Decreasing oxidative stress with choline and carnitine in women. J Am Coll Nutr 2005; 24: 172–176.
Fioravanti M, Yanagi M. Cytidinediphosphocholine (CDP-choline) for cognitive and behavioural disturbances associated with chronic cerebral disorders in the elderly. Cochrane database, issue 2, 2005. London: Macmillan.