and comments on whether those gaps can be filled. Information on the derivation of the DRIs was included to help clarify research gaps.
No Estimated Average Requirements (EARs) were set for infants because of lack of appropriate data. Adequate Intakes (AIs) were set instead. Thus, methods are lacking to estimate the prevalence of inadequate intakes or to plan complementary feeding for infants. This poses a large problem in developing countries where there may be a need for fortified foods.
The AI for all the nutrients for infants in the first six months of age was obtained by multiplying the average daily volume of breast milk (780 mL) times the concentration of the nutrient in breast milk. One serious problem is the accuracy of the data on human milk composition. The reported nutrient values for human milk vary widely among and within different studies. Reasons include small numbers of subjects, changes in composition over the course of feeding and over the course of lactation, improper sampling, effects of supplement use and food fortification on milk composition, and analytical problems. All these problems could be overcome.
A few examples illustrate the nature and extent of the limitations of data on human milk composition. For iron, the average concentration is said to be 0.35 mg/L, but the literature provides values ranging from 0.20 to 0.88 mg/L. The 0.35-mg value is approximately in the middle of that range. One new study from Sweden (Domellof et al., 2004), which has a large sample size relative to other studies, reports a value of 0.29 mg of iron per liter of breast milk, which, in practice, is considerably lower than the 0.35-mg value in current use. For vitamin A, an average of 485 µg/L is the value chosen, but the values considered ranged from 314 µg/L to 640 µg/L. The situation is similar for vitamin B12, for which a value of 0.42 µg/L was chosen. The lowest reported value, 0.31 µg/L, was from vegans; the highest value, 0.91 µg/L, was from Brazilian women who received prenatal supplements. Folate analysis also has been very controversial. Dr. Allen emphasized that erroneous estimates of