The need for choline is likely to be increased during lactation because a substantial amount of choline is secreted in human milk, and mechanisms for conserving maternal choline status have not been identified. Lactating rats are more sensitive to choline deficiency than are nonlactating rats (Zeisel et al., 1995).

The AI for women during the first 6 months of lactation should be increased above that in the nonpregnant, nonlactating woman to cover the choline that is transferred into milk. For the assumption of an average volume production of 0.78 L/day (see Chapter 2) and an average choline content of milk of 156 mg/L (1.5 mmol/L), this increase is 125 mg/day (1.2 mmol/day). This increase is based on an assumption of 100 percent efficiency. It is not known whether de novo synthesis of choline increases during lactation. Women who are breastfeeding older infants who are also eating solid foods may need slightly less because of a lower volume of milk production.

Choline is widely distributed in foods, with most of it in the form of phosphatidylcholine in membranes. Foods that are especially rich in choline compounds are milk, liver, eggs, and peanuts. It is possible to consume a diet of normal foods that delivers 1 g/day of choline (Zeisel et al., 1980b). Lecithins added during food processing may increase the average daily per capita consumption of phosphatidylcholine by 1.5 mg/kg of body weight for adults (this corre-