of the
.eed to ingest a significant amount of protein at each meal,
or whether it is sufficient to consume protein in variable amounts
at different meals as long as the average daily intake meets or exceeds the recommended or safe protein intakes.
According to FAO/WHOIUNU (1 1), estimates of protein requirements refer to metabolic needs that persist over moderate
periods of time. Although protein and amino acid requirements are conventionally expressed as daily rates (of intake) there is no
implication that these amounts must be consumed each and every
day. Therefore, it is not essential, at least in adults, that daily
intakes of protein, or presumably of each indispensable amino acid, must equal or exceed the physiological requirement; it is
apparently sufficient for the average intake over a number of days to achieve this level. This pattern of intake would allow main
tenance of an adequate protein nutritional state.
There is a limited database that we can consult to make a definitive conclusion on the timing of consumption of comple
mentary proteins or of specific L-amino acid supplements for pro
teins that are deficient in one or more amino acids. Earlier work
in rapidly growing rats suggested that delaying the supplementation of a protein with its limiting amino acid reduces the value
of the supplement (35-38). Similarly, the frequency of feeding of diets supplemented with lysine in growing pigs affects the
overall efficiency of utilization of dietary protein (39, 40). There are few data available from human studies to assess the signifi
cance of these findings. However, the relevance of rat and pig
studies can be questioned in view of the profoundly different
qualitative and quantative characteristics of protein metabolism in rats and pigs compared with human subjects (41). Our studies in human adults showed that overall dietary protein utilization
was similar whether the daily protein intake was distributed
among two or three meals (42). However, the supplementary ef
fect in children of the addition of Phaseolus vulgaris to a maize
bean diet was somewhat less when the supplement was given at intervals of > 6 h (