Discussion (summarized by A.M. Prentice)

Initially, the discussion focused on the energy density of breast milk. Butte expressed general agreement with the suggestion that the energy density of suckled breast milk may be 70 kcal/100 mL, i.e., lower than previously assumed, but she did not advocate the use of the doubly-labelled water method for the determination of the energy content of human milk. Based on 24-hour expression and bomb calorimetry, the average gross energy at 4-16 weeks was 64 kcal/100 mL. When challenged that 'unphysiological' expression may increase the energy content, both Butte and Dewey responded that there was an inverse correlation between volume expressed and energy density which would tend to refute this suggestion.

Dewey expressed surprise at the high milk volumes (850 mL/d) predicted by the isotope method in the Lucas study. These were higher than in her own studies (760 mL/d) and higher than the generally accepted norm for well-nourished women (around 750 mL/d). If, for any reason, the intake had been overestimated this would obviously lower the estimate of energy density. It was agreed that some fine-tuning may be needed, but that there was substantial agreement between Houston, Davis and Cambridge that the energy intakes of breast-fed babies appeared to be considerably lower than had hitherto been assumed.

The WHO/FAO/UNU 1985 recommendations were defended against implied criticisms. Most of the food intake data used as the basis of the requirements came from formula-fed infants, and may well still be appropriate for such children. It seems important to determine why formula-fed children consume more and whether their level of intake may be harmful in view of reports that they have to dissipate most of the energy.