pregnant, nonlactating women gives an EAR for niacin for lactation of 13.4 mg, rounded down to 13.

The data in Table 6-1 suggest a CV for the niacin requirement that is greater than 10 percent. The wide variation in the efficiency of converting tryptophan to niacin may contribute to the larger apparent variation. Thus, a CV of 15 percent is used because information is not available on the standard deviation of the requirement during lactation; the RDA is defined as equal to the EAR plus twice the CV to cover the needs of 97 to 98 percent of the individuals in the group (therefore, for niacin the RDA is 130 percent of the EAR).

The RDAs given above are not expected to be sufficient to meet the needs of persons with Hartnup’s disease, liver cirrhosis, or carcinoid syndrome or of those on long-term isoniazid treatment. As for other B vitamins, extra niacin may be required by persons treated with hemodialysis or peritoneal dialysis, those with malabsorption syndrome, pregnant women bearing multiple fetuses, and women breastfeeding more than one infant.

Data obtained from the 1995 Continuing Survey of Food Intakes by Individuals indicate that the greatest contribution to the niacin intake of the U.S. adult population comes from mixed dishes high in meat, fish, or poultry; poultry as an entree; enriched and wholegrain breads and bread products; and fortified ready-to-eat cereals