Choline is a very important compound found in both the human body and a majority of our common dietary sources. It is required for the synthesis of many vital compounds, including, acetylcholine, phosphatidylcholine and sphingomyelin. Choline also serves a methyl donor and is, therefore, an integral component in many biochemical reactions.
Choline’s primary role exists as a precursor for the formation of other compounds in the body. This underscores its essentiality in human physiology. For example, choline is needed to produce Acetylcholine; a vital neurotransmitter that provides for a multitude of functions throughout the body, thereby making choline indispensable in neural functioning. Choline is also a component of phosphatidylcholine, (commonly referred to as lecithin). Phosphatidylcholine is part of the membrane of cells and also acts as an essential component of bile, aiding the solubilization of cholesterol.
As mentioned, choline is necessary for neurological function and is recommended in higher doses for pregnant women to ensure proper development of the nervous system in fetuses. Emerging research is also emphasizing choline’s importance in cardiovascular and liver health, and may also play a role in cancer prevention. Because foods contain only trace amounts of free choline, supplementation of this nutrient may be critical for achieving enhancements in physiological functioning.
Choline can be found in various food sources, most notably lecithin, which is approximately 13% choline by weight. High concentrations of lecithin can be found in egg yolks, legumes, meat (especially liver), milk, soybeans and whole grain products. 
The treatment of conditions associated with memory impairments/deficits with choline has received some interest in clinical research. A double-blind, placebo-controlled study of patients with chronic cerebrovasculopathies was conducted in subjects receivning intramuscular injections of CDP-choline (cytidine diphosphate choline), at levels of 1000 milligrams per day, for two 4 week intervals.  Following the treatment period, the patients receiving CDP-choline were significantly improved over placebo in terms of attention, mnemonic and behavioral capabilities.
The treatment of Alzheimer's disease with choline therapy has been examined and continues to be studied. Research in animals has shown that choline acetyltransferase can actually pass through the blood brain barrier, entering neurons in the brain.  Treatment of a model of Alzheimer’s in these animals demonstrated improvements in memory and cognitive dysfunction.
Choline may be used for chronic blepharospasm, which is an unremitting condition that causes the involuntary closure of both eyelids. Eight patients with a severe case of this disorder received increasing doses of choline starting at 2.1 grams daily, until control of blepharospasm (involuntary winking) was observed, or when side effects proved unbearable.  Three of the patients experienced significant improvements in their symptoms, which were also confirmed objectively via motion picture visualization.
Other conditions for which choline may be useful include; ataxia associated with multiple sclerosis, cerebellar ataxia, and tardive dyskinesia. [5-8]
The dosage of choline may varies and is dependant upon the supplemental form being taken. A standard dosage of choline is 350 - 500 milligrams, administered three times daily.  However, for treatment of conditions like bipolar disorder, the dosage may be as high as 5000 milligrams. Generally, it is also recommended that choline supplements be taken prior to 4:00pm.
- Choline Bitartrate
- Choline Chloride
- Choline Citrate
It is important to note that the majority of these forms are considered limited in their effectiveness to supply the body with adequate amounts of choline. In fact, choline makes up only 13% of lecithin, and this fact must be taken into account when choosing a lecithin-containing supplement. The best supplemental form of choline appears to be phosphatidylcholine, which offers the highest bioavailability of all forms listed above.
Adequate intakes (AI) of choline are published by the Food and Nutrition Board of the Institute of Medicine of the National Academy of Sciences. AIs for age groups are outlined below :
|Age||Adequate intakes (AI)|
|Infants:||0-5 months, 125 mg/day or 8 mg/kg|
|6-11 months, 150 mg/day or 17 mg/kg.|
|Children:||1-3 years, 200 mg/day;|
|4-8 years, 250 mg/day;|
|9-13 years, 375 mg/day.|
|Teenage Males:||14-18 years, 550 mg/day;|
|Teenage Females:||14-18 years, 450 mg/day.|
|Men:||19 and older, 550 mg/day;|
|Women:||19 and older, 425 mg/day.|
|Pregnant Women:||450 mg/day.|
|Lactating Women :||550 mg/day.|
Choline supplementation may potentially cause depression.  One study showed that in patients with tardive dyskinesia, who were receiving 9 grams per day of choline, developed mild to moderate depression. Once choline therapy was discontinued, the depression improved. The authors noted that this may be an expected side effect of choline therapy, as there is clinical evidence suggesting that depression may be directly associated with cholinergic hyperactivity.
Common side effects attributed to elevated levels of choline in the body include increased salivation and nausea.  With higher doses of pure choline, patients may notice a fishy odor form the intestinal tract, caused by intestinal bacteria action on the excess choline. This can be avoided by taking choline in the phosphatidylcholine form.
Choline deficiency is unlikely, as it is obtained from the diet or from catabolism (breakdown) of phospholipids in the membrane of all cells. If choline is not readily available from either of these sources it can also be synthesized in the body from two different amino acids, either methionine or serine.  The biosynthesis of choline takes place in the liver.
However, lower levels of choline may be associated with fatty liver, gastric ulcers, kidney and liver impairments, cardiac symptoms, hypertension, and the inability to digest dietary fats. 
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