Nutrient intakes of thirty-nine infants were determined by a combination dietary record/recall method at two, four, eight, and twelve weeks of age. Infants were grouped according to feeding method: Formula only formula plus solid foods, human milk only, and human milk plus solid foods. The contribution of various types of solid foods and milk to total energy and nutrient intakes within each feeding regimen was determined. The effect of feeding regimen upon renal concentrating capacity was assessed by determining plasma osmolality, sodium, and urea in blood samples drawn at four and eight weeks of age. Results indicate that milk was the major source of energy and of ten of the thirteen nutrients tabulated at all ages examined. Data also suggest that solid foods replace, rather than supplement, human milk or formula on a caloric basis. The feeding methods examined did not influence plasma osmolality and sodium levels, despite significant differences in dietary renal solute load observed between breast-fed and formula-fed infants. Plasma urea levels were positively correlated with protein intakes at eight weeks of age. Implications of the data for counseling parents are discussed.
PIP: An investigation was undertaken in a university community in Illinois to obtain quantitative data on the types and amounts of food consumed by full-term infants under 3 months of age, to determine the partitioning of energy and nutrient intakes between human milk or formula and other foods, and to determine the effect of feeding method on dietary renal solute load and osmolality, sodium, and urea. The 22 male and 17 female apparently healthy and full-term infants were born between August 1, 1977 and April 15, 1978. The mean age of the 39 mothers was 24.1 years (range, 16-36 years). Infant food intakes were obtained using a combination dietary record/recall method. The mothers kept 3-day dietary records for their infants at ages 2, 4, 8, and 12 weeks. The infants were followed longitudinally and were classified according to the feeding method used at each age. Energy and nutrient intakes (except chloride from solid foods) were tabulated using a computer program based on data provided by infant food manufacturers. 26 of the infants were formula fed; 13 were breast fed. By the age of 8 weeks, 83% of the formula fed infants were receiving solid foods, compared to 31% of the breast fed infants. Infant cereal (rice and oatmeal) was the type of solid food most often introduced first. Strained fruits were offered next most often as a 1st food. Vegetables and vegetable-meat combination dinners were not offered to infants in this investigation as the 1st solid foods. Milk was the major source of energy, protein, carbohydrate, fat, calcium, sodium, chloride, potassium, thiamin, riboflavin and pyridoxine for infants receiving formula only, formula plus solid foods, breast milk only, and breast milk plus solid foods. Solid foods and/or nutritional supplements provided significant amounts of iron, vitamin A, and ascorbic acid. Supplemental foods had the greatest impact on nutrient intakes of breast fed infants. Addition of solid foods and formula to diets of breast fed infants resulted in higher protein, sodium, and iron intakes and increased their dietary renal solute so that it was similar to that of the formula fed infants. The feeding regimens failed to influence plasma osmolality and sodium, despite the significantly higher renal solute load imposed by the diets of formula fed infants compared to totally breast fed infants at 4 and 8 weeks. Plasma urea levels reflected dietary protein at age 8 weeks. Most of the sodium ingested by the formula fed infants was provided by formula. The study findings support delaying solid foods until 5-6 months of age.