Following are the subcommittee's research recommendations that concern mainly the nutrition of the lactating woman or of her breastfed infant.

• Research is needed to develop indicators of nutritional status for lactating women.

First, the identification of normative values for nutritional status should be based on observations of representative, healthy, lactating women in the United States. In addition, indicators are needed both of (1) risks of adverse outcomes related to the mother's dietary intake and (2) the potential of the mother or her nursing infant to benefit from interventions designed to improve their nutritional status or health.

• Research is needed to identify groups of lactating women in the United States who are at nutritional risk or who could benefit from nutrition intervention programs.

In general, it has been difficult to identify groups of mothers and infants in the United States with nutritional deficits that are severe enough to have measurable functional consequences. Priority should be given to the study of lactating women in subpopulations believed to be at risk of inadequate intake of certain nutrients, such as calcium (black women) and vitamin A (low-income women). The potential influence of culture-specific food beliefs on nutrient intake of lactating women should be included in any such investigations.

• Intervention studies of improved design and technical sophistication are needed to investigate the effects of maternal diet and nutritional status on milk volume; milk composition; infant nutritional status, growth, and health; and maternal health.

The nursing dyad (the mother and her infant) has seldom been the focus of studies. Thus, a key aspect of this recommendation is concurrent examination of the mother, the volume and composition of the milk, and the infant. The design of such research should be adequate for causal inference; thus, if possible, it should include random assignment of lactating subjects to treatment groups. Appropriate sampling and handling of milk for the valid assessment of energy density, nutrient concentration, and total milk volume are essential, as is accurate measurement of nutrient concentrations.