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Choline is a nutrient required by the body. It does not meet the classic definition of a vitamin because the body makes some choline, but not enough to support health. The remainder must be acquired through diet. For practical purposes, choline is grouped with the B-complex vitamins because it is a water-soluble compound that performs some functions similar to these vitamins.
Choline has several functions in the body. It is incorporated into the fat (lipid)-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 neuro-transmitter that transfers information from nerves to muscles. Acetylcholine is also thought to be important to memory and learning in the brain. Finally, choline, like several other B vitamins, 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. When too much homocysteine
(Illustration by GGS Information Services/Thomson Gale.)
builds up, it appears to damage blood vessel walls and promote clot formation in blood vessels.
Well-designed, reproducible 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. Clinical trials are underway to investigate the effects of choline oh Alzeheimer”s disease, heart disease, and fetal exposure to alcohol.
Choline has not been the subject of as much research as many of the other micronutrients. Not until 1998 did the Food and Nutrition Board of the United States Institute of Medicine (IOM), a part of the National Academy of Sciences, declare choline to be an essential nutrient and establish dietary guidelines for it.
Normal choline requirements
The IOM has developed 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) defines the average daily amount of the nutrient needed to meet the health needs of
97–98% of the population. The Adequate Intake (AI) is an estimate set when there is not enough information to determine an RDA. The Tolerable Upper Intake Level (UL) is the average maximum amount that can be taken daily without risking negative side effects. The DRIs are calculated for children, adult men, adult women, pregnant women, and breastfeeding women.
- children birth–6 months: AI 125 mg; UL not established. All choline should come from breast milk and infant formula or infant food.
- children 7–12 months: AI 150 mg; UL not established. All choline should come from food, not dietary supplements.
- children 1–3 years: AI 200 mg; UL 1,000 mg
- children 4–8 years: AI 250 mg; UL 1,000 mg
- children 9–13 years: RDA 375 mg; UL 2,000 mg
- boys 14–18 years: IA 550 mg; UL 3,000 mg
- girls 14–18 years: IA 400 mg; UL 3,000 mg
- adult men age 19 and older: RDA 550 mg; UL 3,500 mg
- adult women age 19 and older: RDA 425 mg; UL 3,500 mg
- pregnant women all ages: RDA 450 mg; UL 3,500 mg
- breastfeeding women all ages: RDA 550 mg; UL 3,500 mg
Sources of choline
Research suggests that the body makes only between 10% and 20% of the choline it needs to maintain health. The rest comes from diet. 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. Much less information is available about the choline content of specific foods than is available for other nutrients. Most people can meet the AI levels of choline through their normal diet. Some foods that have been analyzed for choline are listed below.
- beef liver, 3 ounces fried: 355 mg
- wheat germ, 1 cup toasted: 172 mg
- egg, 1 large: 126 mg (choline is concentrated in the yolk)
- cod, 3 ounces cooked: 71 mg
- Brussels sprouts, 2 cup cooked: 63 mg
- broccoli, 1 cup cooked: 62 mg
- peanut butter, 2 Tablespoons: 20 mg
- milk chocolate, 1.5 ounces: 20 mg
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 for affected children later in life.
Large excesses (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).
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Linus Pauling Institute. Oregon State University, 571 Weniger Hall, Corvallis, OR 97331-6512. Telephone: (541) 717-5075. Fax: (541) 737-5077. Website: http://lpi.oregonstate.edu>
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Helen M. Davidson