FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS	ESN:FAO/WHO/UNU EPR/81/17 August 1981
	WORLD HEALTH ORGANIZATION
	THE UNITED NATIONS UNIVERSITY

Provisional Agenda Item 2.4.2

Joint FAO/WHO/UNU Expert Consultation on Energy and Protein Requirements

Rome, 5 to 17 October 1981

COMMENTS ON THE 1973 JOINT FAO/WHO REPORT ON ENERGY AND PROTEIN REQUIREMENTS WITH PARTICULAR REFERENCE TO INFANTS, CHILDREN AND ADOLESCENTS

by

G.B. Forbes

Department of Pediatrics

Medical Center

University of Rochester

Rochester, N.Y.

Comments on other sections of the 1973 Bulletin page 10, section 2.2:

I question the reason for the difference in appraoch used for energy requirements and protein needs. The former is fully as important as the latter.

page 12, section 3.3:

The stature of the reference man and woman should be given. It is well known that weight is a function of height for adults as well as children, and the Table in the annex (p. 100) ought to include information on this.

page 12, section 3.5:

It is my hope that the calorie will be retained. There is no valid reason for coverting energy units to joules; indeed it seems to be an affectation!

page 14, section 3.9:

I am confused about the use of the term “protein utilization,” particularly as it is applied to adults. If one feeds an adult more nitrogen than is needed to cover obligatory losses, then the excess will be excreted. For example, if the obligatory N loss for an adult is 2.5 gm (Figure 2, p. 41), and intake is 5.0 gm, this does not mean that only 50 per cent of N from this dietary source is “utilized” by the body. The term “utilization” has meaning only in situations there is actual augmentation of body N, either by growth or recovery from malnutrition.

page 22, first sentence of 3rd paragraph:

The implication here is that 11–13% of calories from protein maybe too low. If so, this is unfortunate, since human milk supplies only 8% of calories from protein.

page 17, regarding minimal protein for adults:

One could cite an additional reference showing that 40 gm protein daily is sufficient for adult men. (F. Strieck, Ann. Intern. Med. 11, 643–650, 1937).

page 23, line 21–23:

Why select “arbitarily” for body size when there are good data available on actual size? The phrase “they have no other significance…” weakens your argument, and contravenes the use of the adjective “reference” as applied to adults. The word “reference” is equivalent to “standard” and will be so construed by many readers.

page 26, body composition:

Many more data are now available on lean weight and fat in both sexes, including the changes which occur with advancing age. The mean fat-free mass in U.S.A. and European males is 60–65 kg, and in females 40–43 kg.

page 31:

Table 3 omits consideration of body composition. The vast majority of 70 kg women, for example, will be moderately obese.

page 70, 71:

Table 23 is in Terms of N, while Table 25 lists protein. This is confusing to the casual reader; why not list protein in both?

Tables 7,8,26,27:

It seems rather strange that adolescent male requires no more calories than the “reference” 20–39 year old, whereas the adolescent female does require more than the young adult woman. Perhaps more recent data will clarify this paradox.

Table 10:

Why are females omitted?

Table 7,8:

Values for “energy per person per day” should be rounded off to the nearest 100 kcal; those for “per kg per day” to the nearest 5 kcal. As they now stand, more accuracy is implied than is warranted. Apparently the data published by Wait et al., (Am. Jour. Clin. Nutr., 22, 1383, 1969) were not used in constructing Table 7. In studying “well noursihed Chicago children” these observers recorded lower calorie intakes for girls 1–16 years than those listed in Table 7, lower intakes for boys 12 years and younger, but higher intakes for older boys.

Section 5.7.2 Growth (p. 37):

I don't see the revelance of including data from rats, nor do I see the point of using data from nitrogen balance in making these calculations. Growth in the infant and child involves fat as well as lean, as does recovery from malnutrition in the adult.

Table 8, page 35:

Since this merely presents data from Table 7 in condensed form, it should be omitted.

page 39:

Perhaps a note should be added to the effect that alocohol consumption by adolescents is increasing.

Under Section 5.8 (2), isn't the value of 1500 kcal a bit too high? I seem to recall that slightly built women can subsist on 1200 kcal, but I cannot give a reference for this.

Page 32: Of the 1973 Bulletin

5.5 Energy Requirements of Infants, Children and Adolescents

During the period of growth, energy requirements should be related to some measure of body size, and the most convenient measure is body weight. It should bo noted that, with the possible exception of the prematurely born infant, the energy “requirement” cannot be strictly defined; rather the information to follow is a reflection of energy intakes by healthy young persons. Growth requires energy, so the rate of growth in essence contitutes a biological assay of dietary adequacy: a diet replete with all other nutrients cannot support normal growth in the face of a poor caloric intake, so energy is the prime prerequisite.

Prematurely born infants. Although these tiny babies are few in number (no more than 10 percent of live babies in most societies) modern medicine now permits many of them to live. For the first few weeks of life their existence is a precarious one, and proper nutrition is essential to their health and well being. Tables A gives energy requirements. The proportion of energy used for growth is relatively high; and due to their rather high surface area: weight ratio (0.1 m²/kg for 1000 gm baby compared to the adult ratio of about 0.025) special attention must be given to environmental temperature. It is estimated that the metabolic rate of a small baby can be doubled when the ambient temperature is reduced, so a neutral thermal environment is essential.

Term infants. Energy needs during the first 6 months of life can be estimated from the observed intakes of normally growing infants. The data of Table 6 are derived from Fomon's ( ) observation on infants fed human milk and cow's milk formulas. (Note: this table is to be modified slightly). The two milks were comparable in promoting adequate growth; and studies have shown that milks based on processed soy flour are just as good (Fomon). The Table depicts the average energy intake; it is recognized that there is considerable intersubject variability as well as day-to-day variations in intake by the same infant. Both activity level and growth rate vary among infants. All of these factors preclude the setting of precise energy requirements.

It is now common practice to introduce solid foods (beikost) during the first few months of life, both in breast fed and bottle fed babies. Recent surveys (Fomon, 1975) in the U.S.A. show that by age 6 months milk provides only about half of the total energy intake, and at one year of age this has dropped to one-third. Rowland and Paul Found that supplementary foods were also given early in breast fed Gambian infants, and it has been shown that growth is improved in breast-fed Pakistani infants when solid foods were introduced prior to 5 months of age (Underwood, et al). It is obviously important that these non-milk foods be of good nutritional value.

Illness in infants is usually accompanied by cessation of weight gain, and often by weight loss. This means that satisfactory recovery demands a period of “catch-up” growth, with supernormal growth velocity, if the infant (or child for that matter) is ever to attain the growth status that would have occurred had the illness not spuervened. A good rule of thumb is to offer 1 ½–2 times the usual calories per kg, or to offer calories based on the basis of ideal body weight. Waterlow ( ) has emphasized the great need for adequate calories in recovery from malnutrition.

This illustrates one pitfall in the use of body weight as a basis for energy needs, since it guarantees that the large baby will be given more and the small baby less than the average amount; hence overnutrition is promoted in the former and undernutrition in the latter. A possible though not completely satisfactory solution is to feed every one on the basis of ideal body weight.

Children and adolescents. In recent years assays of body composition have been made on large numbers of children and adolescents, and it is now possible to construct growth curves for lean body mass and for body fat. Figure (to be supplied) shows such curves for U.S.A and German children and adolescents as determined by ⁴⁰K counting, and for Czech children and adolescents as determined by body density (note: I am attempting to find data for Japanese children).

The lean component of the body (LBM) accounts for almost all of the metabolic rate, so its size together with physical activity is of importance in determining the energy needs. The Figure shows that there is very little sex difference in LBM until puberty, when boys far surpass girls in LBM growth so that by age 18 the male: the female ratio is about 1.4: 1. This ratio is higher than that for height (1.07: 1) and for weight (1.15: 1). When the sex difference in physical activity is superimposed, it is evident that energy needs of adolescent boys far exceed that of adolescent girls.

The data in Table 7 are based surveys of food consumption by children in the U.S.A and the U.K. These are average values, and there is considerable individual variation, due to no doubt to a) variation in growth rate (the pubescent growth spurt varies in intensity and timing; for example the standard deviation of age at menarche is about years); b) activity level; c) selfimposed dietary regimes, such as the modern tendency for some adolescent girls to limit weight gain by dietary restriction,

In making recommendations for energy needs one should not discount the role of appetite. It is apparent that body weight is regulated in infants and children as well as in adults, so in normal individuals appetite is a good guide to energy needs.

The beneficial role of physical activity should be stressed. This generates a need for more calories without a documented need for larger amounts of other nutrients; hence exercise tends to protect the individual against nutrient deficiencies.

Page 37 of the 1973 bulletin:

5.7.2 Growth.

The energy cost of growth can be estimated from data obtained on infants recovering from malnutrition and from adolescent girls recovering from anorexia nervosa. Assuming that maintenance energy requirement is 1.5 × BMR, the recorded cost is in the range of      to      kcal per gram of tissue gain.

5.7.3 The Requirements for Maintenance and Growth Compared with Observed Intakes.

Table 10 shows energy needs for maintenance and growth of boys and girls at different ages. (Note: ? add girls; was maintenance need caluculated from BMR? If so, it should be stated). Worthy of note is the conclusion that except for the infant the amount of energy needed for growth is less than five percent of the total. The difference between estimates of maintenance plus growth needs and the observed intakes represents the amount of energy potentially available for activity. While there are no satisfactory direct estimates of the energy costs of activities in infants and children, in adults the energy available for activity calculated by this method is in reasonable agreement with direct estimates of energy expenditures.

Section 7.2.3 Energy Requirements of Children and Adolescents:

(I have great difficulty in understanding this section and Tables 26 and 27. It would appear that the assumptions inherent in the various calculations are most imprecise; the age structure varies among populations, and the fraction of the population engaged in “activities other than moderate” is most difficult to determine. This section needs to be re-written).

References

Underwood, B.A., Van Arsdell, H., Blumenstiel, E., and Scrimshaw, N.S., Implication of available information on breast-feeding worldwide, in Infant and Child Feeding, J.T. Bond et al., eds., N.Y. Academic Press, 1981, pp. 77–96.

Fomon, S.J., Infant Nutrition, 2nd ed., Phil., W.B. Saunders, 1974.

Fomon, S.J., What are infants fed in the United States? Pedicatrics 56, 350 - , 1975.

Waterlow, J.C., Jour. Trop. Pediat. 7, 16 - , 1961.

Barac-Nieto, M., Spurr, G.B., Lotero, H., Maksud, M.G., and Dahms, H.W., Body composition during nutritional repletion of severely undernourished men. Am. Jour. Clin. Nutrition 32, 981–991, 1979.
(males weighing 43kg gained weight but not lean on diet providing 2240 calories and 26 gm protein (52 cal, 0.6 gm/kg), then gained lean-weight on same calories with 2.2 gm protein/kg).

Sinclair, L.C., Drsicoll, J.M., Jr., Heird, W.C., and Winters, R.W., Supportive management of the sick neonate: parenteral calories, water, and electrolytes. Pediat. Clin. No. America 17, 863 - , 1970.

Forbes, G.B., Body composition in adolescence, in Human Growth, ed. by F. Falkmer and J. Tanner, N.Y. Plenum Press, Vol II, pp. 239–272.

Rowland, M.G.M., and Paul, A.A., Factors affecting lactation capacity: Implications for developing countries, in Infant and Child Feeding, J.T. Bond et al., eds., N.Y., Academic Press, 1981, pp. 63–75.

Burmeister, W., and Bingert, A., Die Quantitativen Veränderungen der menschlichen Zellmasse zwischen dem 8 und 90 Lebensjahr. Klin. Wochenschr. 45, 490 - , 1967.

Parizkova, J., Body Fat and Physical Fitness, The Hague, M. Nijhoff, 1977

Cheek, D.B., Human Growth, Phil., Lea & Febiger, 1968.

Forbes, G.B., The adult decline in lean body mass. Hum. Biology 48, 161 - , 1976.