The relationship weight change, protein turnover

between dietary nitrogen balance, in man1’ 2

M. Golden,3 B.Sc., M.B., B.Ch., B.A.O., J. C. Waterlow,4 M.D., Sc.D., F.R.C.P., and D. Picou,5 M.B., B.S., Ph.D.

ABSTRACT sis,

and

who

We have

protein

were

tabolism

recovering

level

of dietary

tions

between

balance, protein

and

in protein

breakdown, breakdown

and Over

protein the

5-fold.

breakdown not

1345-1348,

contribute

metabolism.

range

of

dietary

changes

being

least

to changes

turnover, nitrogen

protein balance

the

were

intake, in dietary

60

on an inadequate in nitrogen

dietary

to 270

intake

intake.

urea.

correla-

intake,

nitrogen

per

in small Changes

or body

meThe

significant cal/kg

resulted

balance

Protein

of urinary

highly

ad libitum

synthein children

.

the enrichment There

and

Large

and

protein-energy-malnutrition

measuring

synthesis

protein

change,

severe and

protein

between

weight

from

[“'N]glycine affect

with did

intake,

recovered

flux

increased

the relationships

dietary

not

change.

rate

of protein

J. Clin. Nutr. 30:

did

protein

weight

synthesis

had

by giving

protein both

and

and

was measured

M.R.C.P.,

examined

breakdown

intake, and

weight.

day,

the

changes in the

rate Am.

1977.

Both infection and trauma usually result in a negative nitrogen balance Because there is increased catabolism of amino acids from the amino acid pool, it has long been assumed that there is an increase in the rate of breakdown of body proteins; however, this is not necessarily the case The availability of amino acids for catabolism can be increased by either an increase in the breakdown rate or a decrease in the synthesis rate of whole body protein In infection the magnitude of this imbalance between synthesis and breakdown depends upon the severity of the illness, the amount of fever, the nutritional status, the immunological and hormonal responses, and the presence of anorexia (1). The infection results in loss of weight or cessation of growth. .

whether the long-assumed increase in the protein breakdown rate with an inadequate diet was the cause of the excessive nitrogen loss. Methods

.

.

In order to examine these determinants of the “catabolic response” individually, we have measured protein synthesis, breakdown, and flux in children recovering from protein-energy-malnutrition and related them to the ad libitum food intake (appetite), the nitrogen balance, and the rate of weight change. We wished to determine whether the rates of synthesis or breakdown were sensitive to dietary change and The American

Journal of Clinical Nutrition

30:

AUGUST

Downloaded from https://academic.oup.com/ajcn/article-abstract/30/8/1345/4650116 by University of Minnesota Law Library user on 27 May 2018

Variation

in protein

intake

Seventeen children who had recovered from severe malnutrition were studied. The diets of the high-pro(em and five of the low-protein group have been described previously (2). The other five in the low-protein group received 107 cal-and 1 .2 g of protein/kg per day. The very low-protein group received 0.6 g of protein and 95 cal/kg per day. Protein turnover was measured as previously described (2) with a [“'Njglycine constant infusion.

‘ From the Tropical Metabolism Research Unit, University of the West Indies, Mona, Kingston 7, Jamaica. 2 Address reprint requests to: Dr. D. Picou, Tropical Metabolism Research Unit, University of the West Indies, Mona, Kingston 7, Jamaica. Visiting Lecturer and Wellcome Trust Research Fellow, Tropical Metabolism Research Unit. Professor of Human Nutrition, Department of Human Nutrition, London School of Hygiene and Tropical Medicine, London, England. “Professor of Experimental Medicine and Director, Tropical Metabolism Research Unit.

1977,

pp.

1345-1348.

Printed

in U.S.A.

1345

1346

GOLDEN

Variation

in dietary

ET AL.

intake

Ii

:OO4Ox.19 r:093 pc000l

12

Five children were studied four or five times during and after recovery from severe malnutrition. Two children received a soybean-based formula and three received a cow’s milk-based formula.6 The diet supplied 3 1 g of protein/liter and 1 ,350 cal/liter. The children were all fed the diets ad libitum. Protein synthesis, breakdown, and flux were measured with a single dose o [“'Nglycine and determining the amount excreted in the urine (3). The proportion of the dose excreted is then equal to the proportion of the flux which is excreted. This technique gives values that are not significantly different from the constant infusion method (3).

10 PROTEIN FLUX gm kgday

8 6

12

y =0031x .1.9 r=0.87

10

p

The relationship between dietary intake, weight change, nitrogen balance, and protein turnover in man.

The relationship weight change, protein turnover between dietary nitrogen balance, in man1’ 2 M. Golden,3 B.Sc., M.B., B.Ch., B.A.O., J. C. Waterlow...
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