Inadequate levels of choline have been linked to an increased risk of heart disease due to this nutrient's effect on homocysteine levels in the blood. The complex interactions between choline and homocysteine and the full effect of homocysteine on heart disease remain under study. Fortunately, most people get enough of this nutrient through food, so supplements are rarely necessary.
Choline
Choline is an essential nutrient, though it isn't technically a vitamin or mineral. While the body can synthesize small amounts of choline, it isn't enough for survival. Choline can be found in every cell of the body, and it aids in fat metabolism, cell signaling, maintaining cell membranes and neurotransmitter activity. The adequate intake of choline for men over 19 is 550 mg a day, and for women it is 425 mg per day. Most people get between 730 and 1040 mg per day. The tolerable upper limit for choline is about 3500 mg per day -- far more than most people get.
Homocysteine
Homocysteine is a compound in the body that is associated with heart disease. High levels of homocysteine in the blood indicate an increased risk of heart disease. A February 2005 study in the "American Journal of Clinical Nutrition" found that deficiencies in choline were linked to higher levels of homocysteine in the blood. The rise in homocysteine levels can occur in as few as four hours when choline is removed entirely from the diet. Another study in the July issue of the "American Journal of Clinical Nutrition" found that 2.6 g of choline supplements daily for two weeks lowered homocysteine levels in otherwise healthy men.
Mechanism
Normally, homocysteine is cleared from the bloodstream after being converted to methionine. For this conversion to occur, some other compound must donate a methyl group to homocysteine. In the body, choline is converted into betaine, a powerful methyl donor that helps clear homocysteine from the body. Without enough choline, there is not enough betaine to lower homocysteine levels and reduce the risk of heart disease.
Sources
In food sources, choline is typically found in the form of phosphatidylcholine. Good dietary sources of choline include beef liver, wheat germ, eggs, fish, broccoli, Brussels sprouts, milk and peanut butter. Choline supplements are available, but they do not contain 100 percent choline. Instead, the choline in supplements is bound to other molecules, dropping the actual choline percentage in the pill to as low as 13 percent of the total weight.
References
- Linus Pauling Institute; Choline; Victoria J. Drake; January 2008
- Nutra Ingredients: Choline Impacts Heart Disease Risk Factor; February 2005
- "American Journal of Clinical Nutrition"; Choline Supplemented as Phosphatidylcholine Decreases Fasting and Postmethionine-loading Plasma Homocysteine Concentrations in Healthy Men; M. R. Olthof, et al.; July 2005
