Choline

Choline is a nutrient required by the body. It does not meet the classic definition of a vitamin—a nutrient that the body needs in small amounts to remain healthy but cannot manufacture for itself—because the body makes some choline, but it does not make enough. The remainder must be acquired through diet. Choline is often grouped with the B-complex vitamins because it is a water-soluble compound that performs some similar functions to these vitamins.

Choline has several actions in the body. It is incorporated into the fat-containing structures in cell membranes and is necessary for the formation of certain signaling chemicals made by cells to activate other molecules. Choline is also necessary for the formation of acetylcholine. Acetylcholine is a neurotransmitter that transfers information from nerves to muscles. Acetylcholine is thought to be important to memory and learning in the brain.

Choline

SOURCE: Office of Dietary Supplements. National Institutes of Health. “Choline: Fact Sheet for Health Professionals.” https://ods.od.nih.gov/factsheets/Choline-HealthProfessional (accessed April 1, 2018).

Like several of the B vitamins, choline is active in the metabolic pathway that breaks down homocysteine and removes it from the body. Homocysteine is an amino acid that circulates in the blood. Research has shown that people who have high levels of homocysteine in the blood are more likely to develop cardiovascular diseases such as coronary artery disease and stroke, and too much homocysteine may also adversely affect fetal health and development.

Choline has not been studied as much as many of the other micronutrients, and it was not declared to be an essential nutrient until 1998. Research suggests that the body makes only between 10% and 20% of the choline it needs to maintain health, so the rest must come from diet.

The Food and Nutrition Board of the United States Institute of Medicine (IOM), a part of the National Academy of Sciences, develops values called Dietary Reference Intakes (DRIs) for many vitamins, minerals, and essential micronutrients. The DRIs consist of three sets of numbers: the recommended dietary allowance (RDA), which defines the average daily amount of the nutrient needed to meet the health needs of 97%–98% of the population; adequate intake (AI), an estimate set when there is not enough information to determine an RDA; and tolerable upper intake levels (UL), the average maximum amounts that can be taken daily without risking negative side effects. The DRIs are calculated for children, adults, and pregnant and breastfeeding women.

The IOM has not set RDAs for choline because of the scarcity of large, long-term dietary studies on this micronutrient. Instead, AI levels have been established for all age groups based on the best research information available. For choline, the AI level was established as the average daily amount needed to prevent the development of a condition called fatty liver, and it may not be the amount needed for other conditions. A 2008 study on Mexican American men found that higher levels were needed to accommodate rises in homocysteine. The IOM's recommended AI and UL levels of choline for each age group (in milligrams) are:

Choline for children younger than 12 months should come from breast milk and infant formula or food and never from dietary supplements.

Foods rich in choline include beef liver, egg yolks, peanuts, and soybeans. Most choline in foods is in the form of phosphatidylcholine, which is also known as lecithin. Most people can meet the AI levels of choline through their normal diet. Sources of choline include:

Choline chloride and choline bitartrate are also sold as a dietary supplements. Choline is also found in dietary supplements marketed as lecithin. Soybeans are the most common source for lethicin in dietary supplements. These supplements contain a much smaller and more variable amount of choline than choline chloride or choline bitartrate supplements. Consumers should read the lethicin labels carefully. Some children's multivitamins also contain choline.

Moderate choline deficiency is associated with an increase in the blood levels of homocysteine. High levels of this molecule are known to increase the risk of cardiovascular disease. Extreme choline deficiency can result in a condition called fatty liver. Fat accumulates in liver cells where, in the absence of choline, it cannot be packaged and transported through the body. As a result, fats in the blood called triglycerides increase, creating an increased risk of heart disease and other health problems. Choline deficiency in pregnant women appears to have a negative effect on the development of the fetal brain and may cause learning, memory, and attention problems later in life.

Large excesses,.35 oz. (10 g) or more, of choline can cause nausea and extreme sweating. However, the most noticeable symptom of excess is the development of a highly unpleasant fishy body odor that results from the excretion of a choline breakdown product from the skin, urine, and breath. Large doses of choline dietary supplements do not appear to improve either physical or mental performance, nor do they appear to confer any specific health benefits.

Methotrexate, a drug used to treat cancer, psoriasis, and rheumatoid arthritis, causes choline deficiency in laboratory animals. Individuals taking this drug should discuss possible side effects with their physician. Choline also is involved in many of the same metabolic pathways as other B-complex vitamins. Deficiencies or excesses of any of these B vitamins may potentially alter choline metabolism.

No complications are expected when choline is taken in amounts equal to or exceeding the AI level. Doses much higher than the UL level have been tolerated without any obvious serious negative side effects (but also without any observed benefits). Adequate levels of choline are obtained through a healthy diet, and supplementation is not needed unless recommended by a physician.

Animal studies suggest that choline has a positive effect in stimulating the developing brain of the fetus and that choline supplements given after birth may offset some of the effects of fetal alcohol exposure. Some dietary supplement sellers have exaggerated these results, calling choline a “miracle brain supplement.” Pregnant and breastfeeding women do need to eat a diet that provides adequate intake of choline, as choline deficiency may adversely affect brain development. However, there is no evidence that choline supplements will produce the opposite effect and increase an infant's intelligence.

See also Detoxification diets ; Dietary reference intakes (DRIs) ; Dietary supplements ; Vitamins .