CALORIC AND PROTEIN INTAKES OF CHILDREN BETWEEN 1 AND 18 YEARS OF AGE
Authors: Burke Bertha S. , Reed Robert B. , Berg Anna S. van den , Stuart Harold C. 
Published: December 2021

The cross-sectional distributions of the data on total caloric and protein intakes for the 64 girls and 61 boys in the Maturity Series from 1 to 18 years are presented in Figure 1 and Table I, and the findings are discussed. Wide variation with age and sex are evident.

The accompanying graphs present the types and amounts of difference and similarity found in individual curves within a given pattern in contrast to those in other patterns. For example, caloric intakes of boys in the "consistently high," "consistently medium" and "consistently low" groups generally conform to the cross-sectional norm for the boys in the Maturity Series with regard to rate of change in intake from year to year. However, very wide differences are shown among these groups in overall level of intake. See, for example, Boys 270 (HHH), 253 (MMM) and 196 (LLL).

The boys in the other pattern groups, in contrast, change their levels of caloric intake appreciably from one age interval to another in relation to the norm. There are marked inter-pattern differences in direction of change, for example, see Case 140 (MLL) in the "early drop" group in contrast to Case 32 (LHH) in the "early rise" group. There are also marked inter-pattern differences in the timing of these changes, for example, see Case 30 (MHH) in the "early rise" group and Case 283 (MMH) in the "late rise" group.

The "late drop" group, see Case 220 (MML), can be similarly compared to the "early drop" group for difference in timing of change and to the "late rise" group for difference in direction of change.

[See Fig. 3. in Source Pdf]

These graphs call attention to the fact that two distinct patterns of intake, not identified among the boys, are encountered among the girls, i.e., intake patterns manifesting a "consistent rise" and patterns manifesting a "consistent drop" in intake in relation to the norm. Because so few cases fell within these patterns, they are presented together. Girls 10 and 118 show a low caloric intake in the early age interval in relation to the Maturity Series distribution, but change their levels to rank medium in the middle, and high in the last, age interval. The intakes of Cases 239 and 240 are opposite in direction of change.

The "early rise and late drop" and "early drop and late rise" categories serve to illustrate further inter-pattern differences as well as similarities. Cases 163 (LHL) and 180 (MLM) typify the differences between these two pattern groups.

It is also interesting to note that cases falling in different pattern categories may still show certain similarities. For example, compare Case 201 (HHM) in the "late drop" group with Case 206 (MHL) in the "early rise and late drop" group.

[See Fig. 4. in Source Pdf]

In addition to comparisons between patterns, the Figures also permit clear recognition of differences and similarities among individuals classified in the same pattern group. In the "consistently low" group for protein intake, for example, Boys 178 and 140 although lowest and next to lowest, respectively, in overall protein intake and "consistently low" in intake in relation to the Maturity Series distribution, differed at various ages in the rate at which their intakes increased, with the result that Boy 140 had slightly but consistently higher intakes up to age 10, while Boy 178 had the higher intake after age 12. Case 111 in the same pattern group shows a slightly higher overall protein intake, but similarly to Cases 178 and 140, proceeds with varying changes in rate from a low intake in the early years to a maximum between 17 and 18 years. Boys 59 and 31, on the other hand, showing a relatively accelerated rate to a maximum at 14 years, followed by a definite drop in intake, demonstrate a different type of variation in protein intake curves within the range of variability permissible for this pattern.

Another type of intra-pattern difference is illustrated by Cases 182 (MMH) and 188 (MMH). They are both in the "late rise" category, both show considerable rise in intake, but this change is achieved abruptly by Case 182 and gradually by Case 188.

[See Fig. 5. in Source Pdf]

The variety and shadings of individual differences and the gradual transition from one pattern to another should be noted. In the "consistently medium" category the protein pattern of Girl 157 conforms closely to the curve of the cross-sectional averages for the girls in the Maturity Series. The curve of Case 163, on the other hand, shows a relatively rapid increase to an early maximum followed by a comparatively rapid decrease in intake. Case 136 (MMM) in the "consistently medium" group shows a gradual drop in rank during the 17-year period. A comparison of this case with Case 18 (MML) in the "late drop" group points to the fact that the change from one pattern to another is gradual, often with no definite line of demarcation. A similar comparison can be made between Case 163 (MMM) and Case 269 (MHM) in the "early rise and late drop" group.

Short term fluctuations in intake are clearly illustrated in Case 240 (HMM) in the "early drop" group. Her cumulative intakes for both the 6 to 12 and 12 to 18-year periods fell in the medium category although she showed wide variations in the level of intake, with a clearly distinguishable maximum intake during each period.

[See Fig. 6. in Source Pdf]

A comparison of the present findings with the National Research Council's Recommended Allowances (1958) shows that except for the caloric intakes of the girls, the average values for intakes found in this study (especially for protein, and more so for boys than for girls) tend to be higher than the Council's Allowances.

The most marked differences between the present findings and those of certain other selected studies (shown in Figure 2) are found to be the higher level and the higher rate of increase in the protein intakes of the boys in this study.

Enormous differences between individuals of the same age and sex are equally obvious in the findings. At every age, for both sexes, and for both calories and protein, there was at least one child whose intake was approximately twice as high as that of one or more other children of the same age and sex. In fact, it would appear that a cross-sectional mean is of limited value for prescribing the intake of calories or protein for an individual child at any age. Even with longitudinal material, cross-sectional analyses do not allow determination of the different ways in which individuals change their dietary intakes from one age period to another. In the Maturity Series it was evident that many children varied widely from the average pattern in both level and rate of change in intake from year to year.

In order to present the caloric and protein intakes of the boys and girls in the Maturity Series over the entire 17-year period, their individual intakes were classified into pattern groups by a procedure described in the text, using values for cumulative intake within specified age intervals. The frequency of occurrence of these individual longitudinal patterns of protein and caloric intake is shown in Table IV. Figures 3-6 present the curves of data on individual intake of selected cases to represent differences between, as well as within, the various pattern groups for each sex and for both total caloric and total protein intakes.

The values for cumulative intake allow placement and study of each individual child in this series in relation to every other child of the same sex for a given interval of time. The patterns allow a comparison of the intakes of the individual children over whole childhoods in relation to a standard, for example, to the Recommended Allowances of the National Research Council.

Most importantly, these longitudinal patterns of intake can be studied in relation to the manifestations of health and development of the children.