Diurnal and longitudinal variations in human milk sodium and potassium: implication for nutrition and physiology.

Human milk sodium ([Nal]) and potassium ([K)] concentrations were measured every 4 h for 24 h in 28 subjects 3.5 to 32 wk postpartum. A diurnal variation in milk Na was seen, which was reciprocal to K.

Chemical maturation in growing guinea pigs.

Twenty-seven guinea pigs were analyzed chemically for total body water (TBW), fat, nitrogen (N), calcium (Ca), and sodium (Na); 26 were analyzed for potassium (K). Body weights ranged between 82 and 877 g. The data were analyzed by regression analysis.

Comparison of measured and estimated fat-free weight, fat, potassium and nitrogen of growing guinea pigs.

Total body water (TBW), potassium (TBK), nitrogen (N), and fat were measured chemically on 27 guinea pigs ranging in weight from 82-849 g. Measured fat-free wet weight (FFWW) is the difference between body weight and fat extracted with ether. Estimated FFWW is either TBW or TBK divided by a measured or assumed concentration of either water or K in the FFWW.

Fasting and cognitive function.

The effects of short-term fasting (skipping breakfast) on the problem-solving performance of 9 to 11 yr old children were studied under the controlled conditions of a metabolic ward. The behavioral test battery included an assessment of IQ, the Matching Familiar Figure Test and Hagen Central Incidental Test. Glucose and insulin levels were measured in blood.

Total body sodium, calcium, and chloride measured chemically and by neutron activation in guinea pigs.

Body sodium (Na), calcium (Ca), and chloride (Cl) of guinea pigs weighing between 227 and 600 g were measured by total body neutron activation analysis (TBNAA) followed by chemical analysis (CA) on 12-17 animals. Paired t test was used to compare any differences in the results obtained by the two methods. There was no significant difference in the results for the three elements.

Appropriateness of milk use in international supplementary feeding programs.

Recognition of lactose intolerance, debate over the limitedness of dietary energy and protein in specific settings, and the appreciation for the uniqueness and appropriateness of human milk during the 1st yr of life have prompted reexamination of the use of milk in international feeding programs. Substantial proportions of preschool and school-age children from expected populations are lactose intolerant. However, studies in this county indicate that lactose intolerant preschool and early school-age children can tolerate amounts of milk usually consumed.

Human protein requirements: interrelationships between energy intake and nitrogen balance in young men consuming the 1973 FAO/WHO safe level of egg protein, with added non-essential amino acids.

Our recent studies have shown that the 1973 FAO/WHO "safe level of intake" of egg protein (0.57 g/kg/day) is inadequate for maintaining protein nutritional status in young men receiving generous energy intakes. Therefore, an experiment was conducted to determine nitrogen (N) balance and the energy intake needed to support it when supplementary N, equivalent to 0.

Human protein requirements: a long-term metabolic nitrogen balance study in young men to evaulate the 1973 FAO/WHO safe level of egg protein intake.

Six Caucasion male MIT students, age 19 to 23 years, were given a formula diet providing 0.59 g egg protein/kg body weight/day and energy intakes approximately 10% above their usual requirements. Four subjects continued on this diet for 81 to 89 days, but for the two the protein intake was increased after 50 and 59 days because of an excessive rise in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels.

Human protein requirements: the effect of variations in energy intake within the maintenance range.

Protein requirement studies in man generally avoid deficient dietary energy intakes because they decrease the efficiency of nitrogen utilization, but the opposite effect of excess dietary energy is usually overlooked. Four young men were fed the 1973 FAO/WHO safe level of egg protein (0.57 g/kg) at several levels of dietary energy.

Relationship of lactose intolerance to milk intolerance in young children.

The prevalence of lactose intolerance as revealed by the standard lactose tolerance test was compared with the occurrence of intolerance to graded amounts of milk in 69 black and 30 white children. Of the black children studied, 11% of those 4 to 5 years old, 50% of those 6 to 7 years old, and 72% of those 8 to 9 years old were found to be lactose-intolerant, yet no child was intolerant to 240 ml of milk. Symptom responses to greater amounts of milk did not suggest that the frequency of primary lactose intolerance might be a reason for limiting existing milk programs for young children.