Choline is a water-soluble component of several vital chemicals in the body. It is one of the essential nutrients in the body, although it is not by strict definition considered to be a vitamin.
Choline is required to be consumed in the diet in order to maintain a healthy body, because of the fact that only small amounts of choline can be synthesized by humans. The majority of choline in the body is found in phospholipids, which is a specialized fat molecule, the most common of which is called lecithin or phosphatidylcholine.
Biological Functions of Choline
Choline, as well as the other compounds derived from it such as metabolites, have numerous significant biological functions that include:
- Nerve impulse transmission. Choline is a precursor for acetylcholine, which is a vital neurotransmitter that is involved in the control of muscles, memory, and other bodily functions.
- Cell signalling. Sphingomyelin and phosphatidylcholine, which are choline-containing phospholipids that are precursors for ceramide and diacylglycerol, known as the intracellular messenger molecules. The sphingophosphorylcholine as well as the platelet activating factor (PAF) are two other choline metabolites that are also known to be cell-signaling molecules.
- Structural integrity of cell membranes. Choline is used in the synthesis of the phospholipids, sphingomyelin and phosphatidylcholine, which are primarily the human cell membranes structural components.
- Lipid transport and metabolism. Cholesterol and fat consumed in the diet are transported by the lipoproteins, known as chylomicrons, to the liver. Both the cholesterol and fat are packaged by the liver into lipoproteins and these form very low density lipoproteins (VLDL); these can be transported through the blood to the tissues that are in need of them.
Another choline derivative, betaine, is also essential due to its role in the contribution of methyl groups to homocysteine for the formation of methionine.
Choline and folate are metabolically interrelated. The reduced availability of folate can increase the demand for choline as a methyl donor. Decreased choline availability will increase the demand for folate methyl groups.
Choline Deficiency Symptoms
Individual who have insufficient intake of choline can develop a condition known as “fatty liver”, and can also show signs of liver damage. Since choline is required for the formation of phosphatidylcholine portion of very low density lipoprotein (VLDL) particles, inadequate supply of choline can lead to liver damage, as the VLDL particles cannot be synthesized.
Choline deficiency can also lead to reduced blood levels of LDL cholesterol because LDL particles are formed from VLDL particles.
Males who have an adequate intake of vitamin B12 and folate, but have a choline-deficient diet, can develop elevated blood levels of the liver enzyme, alanine aminotransferase (ALT). Having an elevated level of ALT enzyme is one of the signs of having damage in the liver.
Choline RDA
The Food and Nutrition Board (FNB) of the Institute of Medicine established a dietary reference intake (DRI) for choline. The Adequate Intake (AI) for choline is:
|
AGE |
FEMALE (mg/day) |
MALE (mg/day) |
| 0 to 6 months | 125 | 125 |
| 7 to 12 months | 150 | 150 |
| 1 to 3 years | 200 | 200 |
| 4 to 8 years | 250 | 250 |
| 9 to 13 years | 375 | 375 |
| 14 to 18 years | 400 | 550 |
| 19 years and older | 425 | 550 |
| Pregnancy all ages | 450 | – |
| Lactating all ages | 550 | – |
Choline Rich Foods
Some of the significant food sources of choline include eggs; cheese; whole milk; fortified milk; yogurt; fresh basil; mustard; spices such as cloves, cinnamon, curry, ginger, garlic, onion, oregano, paprika, pepper, and turmeric; cereal; oatmeal; canola oil; vegetable oil; fish; chicken and turkey.
References
LPI; USDA; The Franklin Institute; University of Utah Health Care.