The adequacy of the average diets of each group was estimated by comparing the amounts of the various constituents present with the amounts considered necessary for maintaining perfect health.

ANALYSIS OF THE DIETS.

The average diets of each group were analysed and the results have been summarised in Table VII. The analytical data were taken mainly from five sources:—Plimmer (38) for protein, fat, carbo­hydrate and calories ; Sherman (41), for calcium and phosphorus ; Peterson and Elvehjem (37) for iron; and (Faber and Norgaard) Fridericia (16) for vitamins. In the few cases where information could not be obtained from these sources, conversion figures compiled at Glasgow University or the Rowett Research Institute have been used.

Conversion is made in the conventional way directly from the figures of quantities of foods purchased at the shop, and in this conversion allowance is made for the inedible portions. Since no reliable data are available from which to estimate the average wastage of edible constituents either in preparation in the kitchen or at the table, no allowance has been made for this. The wastage, however, is likely to be greatest amongst those who can best afford it. Particular foodstuffs by their different natures will have different proportions of wastage in preparation. Thus, fruit and vegetables with peel will lose some of the edible portion in being peeled, while milk, which needs no preparation, will not lose any significent proportion.

The percentages of total mineral intake provided by different foodstuffs in each of the six groups have been summarised and are shown in Table 8. No reliable published data on mineral waste have been found, but from unpublished figures available it is clear that loss of calcium is negligible (probably less than 1 per cent.), while loss of phosphorus and of iron may vary from 5 to 25 per cent. A great part of the vitamin intake is derived from fruit and vegetables. Without complete information as to the relative quantities of different fruits and vegetables bought, it is impossible to do more than make very rough estimates of the vitamin supply per unit cost of either of these two commodities in each group and hence the figures (given in italics in Table 7) should be considered only as a rough conjecture. There is little doubt, however, that the trend of each is substantially correct.

STANDARDS  OF REQUIREMENTS.

Human requirements for the maintenance of perfect health have not yet been defined with any degree of accuracy. Intensive laboratory researches and dietary surveys have been made by Sherman and his co-workers, and from these a set of standards has been compiled by Stiebeling, of the Government Bureau of Home Economics, U.S.A. The quantities of constituents in the average diets of each group have been compared with the set of standards compiled by Stiebeling (44). These standards are based on the relative requirements of children, adolescents and adults, male and female, as shown in Table VI and weighted according to the distribution of these individual units in the total population.

Table 6
Individuals  by  age,  sex,  and activity groups.
Dietary  Allowance  in : —
Energy Value Protein Calcium Phosphorus Iron Vitamin A Vitamin C
Calories Grams Grams Grams Grams Sherman Units
Child under 4 years 1200 45 1.00 1.00 0.006-0.009 3000 75
Boy, 4-6; girl, 4-7 years 1500 55 1.00 1.00 0.008-0.011 3000 80
Boy, 7-8 ; girl, 8-10 years 2100 65 1.00 1.00 0.011-0.015 3500 85
Boy, 9-10 j girl, 11-13 years . 2400 75 1.00 1.20 0.012-0.015 4000 90
Moderately active woman;   boy 11-12 years; girl over 13 years.
2500 75 1.00 1.20 0.013-0.015 4000 95
Very active woman; active boy,13-15 years
3000 75 0.88 1.32 0.015 4000 100
Active boy over 15 years 3000-4000 75 0.88 1.32 0.015 4000 100
Moderately active man 3000 67 0.68 1.32 0.015 4000 100
Very active man 4500 67 0.68 1.32 0.015 4000 100
Average per head of the population 2810 68 0.9 1.23 0.013-0.014 3800 95

COMPARISON  OF THE DIETS WITH THE  STANDARDS.

For purposes of comparison, the degrees of adequacy of the different constituents have been calculated for each of the six groups as a percentage of the above standards, and these are shown in graph form on page 35.

Table 7
Group I Group II Group III Group IV Group V Group VI Standard reqirements per unit of population
grams % Grams % grams % Grams % grams % grams % Grams
Protein:
Plant 40.9 64.5 43.5 57.2 44.0 52.6 43.8 49.0 42.8 45.3 40.5 41.8
Animal 22.5 35.5 32.5 42.8 39.6 47.4 45.6 51.0 51.6 54.7 57.8
Total 63.4 100 76.0 100 83.6 100 89.4 100 94.4 100 98.3 100 68
Fat
Plant 20.9 29.2 17.9 18.1 14.5 13.2 13.2 13.3 12.2 9.4 11.1 7.9
Animal 50.7 70.8 80.9 81.9 95.1 86.8 107.3 89.0 118.3 90.6 130.4 92.1
Total 71.6 100 98.8 100 109.6 100 120.6 100 130.5 100 141.5 100 98
Carbohydrates 348 381 395 403 406 396
Minerals
Calcium 0.37 0.52 0.61 0.71 0.83 0.95 0.6* 0.9#
Phosphorus 0.81 1.04 1.17 1.28 1.42 1.54 1.23
Iron 0.008 0.0099 0.011 0.012 0.0127 0.0137 0.0115
Sherman Units International Units Sherman Units International Units Sherman Units International Units Sherman Units International Units Sherman Units International Units Sherman Units International Units Sherman Units International Units
Vitamin A 1548 774 2500 1250 3248 2015 4030 2210 4420 2210 5710 2875 3800 1900
Vitamin C 57 838 78 1134 90 1314 108 1577 126 1832 158 2323 95 1400
Calories 2317 2768 2962 3119 3249 3326 2810

 

Assuming the validity of the standards, it will be seen from these graphs, calculated from the figures in Table 7, that the average diet of group I is inadequate for perfect health in all the constituents considered; group II is adequate only in total proteins and total fat; group III is adequate in energy value, protein and fat, but below standard in minerals and vitamins; group IV is adequate in iron, phosphorus and vitamins, but probably below standard in calcium; group V has an ample margin of safety in everything with the possible exception of calcium; in group VI the standard requirements are exceeded in every case.

Nutrient intake by income

It will be noted that calcium has been calculated on two bases: 1 minimum requirement for maintenance of a positive balance, and 2 the same plus a 50 per cent, safety allowance.   The true position for the calcium curve lies probably between these two.   No allowance has been made for the calcium intake from drinking-water.  In some areas this may amount to from 5 to 10 per cent, of the total intake.  Taking   this  into   account, group IV diet  is probably adequate.

The quality of the protein is important, especially for children, and it will be seen from Table 7 that the percentages of protein and fat of animal origin, which are of higher biological value than those of plant origin, increase from group to group. Hence, not only does the intake of the several constituents increase with expenditure on food but the quality of the diet also improves. This improvement is not only in protein and fat but also in mineral elements.

The percentages of total iron, phosphorus and calcium intakes derived from different foodstuffs in the six income groups are shown in Table 8. As a source of easily assimilable calcium and phosphorus, milk ranks above all other foodstuffs. The percentage of total phosphorus from milk rises from 16.5 in group I to 29.8 in group VI, while the percentage of calcium rises from 44.4 in group I to 58.6 in group VI, and in all groups over 60 per cent, of the calcium intake is derived from milk and cheese. Another point of interest is the high percentage of iron derived from bread and flour and potatoes.

It should be kept in view that the standards with which the above comparisons are made are those compiled for the maintenance of perfect health, which is a standard very different from the average health of the community. The fact that the average diets of the lower income groups are inadequate according to these standards does not mean that these people are starving or even suffering from such a degree of ill-health as is recognised in the term disease. These diets may be sufficient to maintain life and a certain degree of activity, and yet be inadequate for the maintenance of the fullest degree of health which a perfectly adequate diet would make possible.

Table 8
Group Total Iron intake per day mg Liquid Milk Condensed milk Cheese Total Bread and Flour Meat Potatoes Vegetables excluding potatoes Fruit Eggs Fish Syrup and jam Total % of total Fe from these foodstuffs
I 8.0 1.4 0.5 1.2 3.1 30.9 24.3 18.8 7.3 6.7 3.7 1.2 0.5 93.4 96.5
II 9.9 2.0 0.3 1.3 3.6 25.9 26.6 16.2 8.4 9.3 4.2 1.9 0.6 93.1 96.7
III 11.0 2.3 0.3 1.6 4.2 25.3 26.6 14.8 8.6 10.3 4.7 2.3 0.5 92.7 96.9
IV 12.0 2.6 0.2 1.7 4.5 21.6 28.7 13.5 9.0 11.2 5.2 2.8 0.5 92.5 97.0
V 12.7 3.3 0.2 1.6 5.1 20.8 29.2 12.8 9.6 10.3 5.6 2.5 0.6 91.4 96.5
VI 13.7 4.1 0.1 1.0 5.2 18.4 29.6 11.2 10.5 12.5 6.4 3.2 0.4 92.2 97.4
Total Phosphorus intake per day g Eggs Fruit % of total P from these foodstuffs
I 0.81 10.9 5.6 5.8 22.3 30.6 17.3 13.0 5.5 2.6 2.5 2.3 0.18 73.98 96.3
II 1.04 16.1 3.9 6.3 26.3 24.6 18.2 10.7 6.1 3.0 3.4 3.7 0.14 69.84 96.1
II 1.17 17.8 3.1 7.0 27.9 21.9 19.1 9.7 6.3 3.2 3.7 4.9 0.12 68.92 96.8
IV 1.28 19.2 2.2 7.3 28.7 20.2 19.4 8.8 6.6 3.7 3.6 5.6 0.11 68.01 96.7
V 1.42 23.6 1.8 6.6 32.0 18.6 18.8 7.9 6.9 3.7 3.0 5.9 0.10 64.90 96.9
VI 1.54 28.8 1.0 4.5 34.3 16.4 19.0 7.0 7.6 4.3 2.8 6.1 0.09 63.29 97.6
Total Calcium intake per day g Vegetables excluding potatoes Potatoes Fruit Eggs Meat Syrup and jam % of total Ca from these foodstuffs
I 0.37 29.2 15.2 17.5 61.9 14.7 7.2 6.7 2.8 2.2 2.1 0.5 36.2 98.1
II 0.52 39.2 9.3 17.0 65.5 10.6 8.3 5.0 3.6 2.2 1.9 0.4 32.0 97.5
III 0.61 41.0 7.2 18.1 66.3 9.0 9.3 4.3 4.0 2.3 1.9 0.3 31.3 97.4
IV 0.71 42.5 6.0 18.1 66.6 7.9 10.6 3.7 3.8 2.4 1.9 0.3 30.6 97.2
V 0.83 49.1 3.9 15.4 68.4 6.8 11.5 3.2 3.3 2.3 1.7 0.3 29.1 97.5
VI 0.95 56.5 2.1 9.8 68.4 5.8 12.9 2.7 3.6 2.6 1.6 0.2 29.4 97.8

 

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