sponds to 0.225 mg/kg of body weight of choline moiety) (SCOGS/ LSRO, 1979).

Choline intake is not reported in the Third National Health and Nutrition Examination Survey (Perloff et al., 1990), the Continuing Survey of Food Intake by Individuals (Perloff et al., 1990), or the Boston Nutritional Status Survey (Hartz et al., 1992), and the choline content of foods is not included in major nutrient databases. There are no reports on choline intake from Canada. Estimated average choline dietary intake in adults consuming a typical U.S. or Canadian diet (as free choline and the choline in phosphatidylcholine and other choline esters) is approximately 730 to 1,040 mg/day (7 to 10 mmol/day) (LSRO/FASEB, 1981; Zeisel, 1981). Calculations of dietary choline intake are based on estimates of the free choline and phosphatidylcholine content of foods (Engel, 1943; McIntire et al., 1944; Weihrauch and Son, 1983; Zeisel et al., 1986). Older assay procedures for choline were imprecise and did not always include glycerophosphocholine or phosphocholine content, making many of the available data unreliable. On the basis of a finding of decreased plasma choline and phosphatidylcholine concentrations when humans were switched from a diet of normal foods to a defined diet containing 500 mg/day of choline (Zeisel et al., 1991), the average dietary intake of choline probably exceeds this level in adults. Infant formulas contain approximately 240 mg/L (2.3 mmol/L) of choline in its various forms. (Holmes-McNary et al., 1996).

Choline is available as a dietary supplement as choline chloride or choline bitartrate and as lecithin, which usually contains approximately 25 percent phosphatidylcholine or 3 to 4 percent choline by weight. In the treatment of neurological diseases, large doses (5 to 30 g) of choline and phosphatidylcholine have been administered to humans (LSRO/FASEB, 1981). There are no reliable estimates of the frequency of use or amount of these dietary supplements consumed by individuals in the United States and Canada.