Table Of ContentHuman Nutrition
Human Nutrition
Cu rrent Issues
and Controversies
EDITED BY
A. Neuberger T. H. Jukes
Lister I nstitute of Preventive Department of Biophysics
Medicine and Charing Cross and Medical Physics
Hospital Medical School, London Department of
Nutritiona~Sciences
University of California,
Berkeley
M~iLIMnw
International Medical Publishers
Published in UK by
MTP Press Limited
Falcon House
Lancaster, England
Copyright © 1982 MTP Press Limited
Softcover reprint of the hardcover 1st edition 1982
First published 1982
All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical.
photocopying, recording or otherwise, without prior
permission from the publishers.
British Library Cataloguing in Publication Data
Human nutrition: current issues and controversies.
1. Nutrition
I. Neuberger, Albert II. Jukes, T. H.
613.2 TX353
ISBN-13: 978-94-011-6260-9 e-ISBN-13: 978-94-011-6258-6
001: 10.1007/978-94-011-6258-6
Contents
List of contributors vii
Preface ix
1 Energy requirements in human beings 1
J. Garrow and S. Blaza
2 Fluoride and fluoridation of water 23
G. N. Jenkins
3 Nutritional status of North Americans 73
G. M. Owen and A. L. Owen
4 Nitrate, nitrite and N-nitroso compounds:
biochemistry, metabolism, toxicity and carcino-
genicity 87
L. C. Green, D. Ralt and S. R. Tannenbaum
5 Vitamin 0 141
H. F. Deluca
6 Vitamin A deficiency and blindness in children 185
S. G. Srikantia
7 Protein energy malnutrition (PEM) in children 197
S. G. Srikantia
8 Endemic pellagra 209
S. G. Srikantia
9 Nutritional eccentricities 217
J. H.Young
10 Laetrile, the bogus 'vitamin B 233
17'
T. H. Jukes
Index 243
v
List of Contributors
S BLAZA A NEUBERGER
Animal Studies Centre The Lister Institute of Preventive
Pedigree Petfoods Medicine
Freeby Lane, Walton-on-the-Wold Charing Cross Hospital Medical
Melton Mobray School
Leicestershire LE14 4RT The Reynolds' Building
England St Dunstan's Road
London W6 8P, England
H F DELUCA G MOWEN
Department of Biochemistry Bristol-Myers Company, International
University of Wisconsin-Madison Division
420 Henry Mall 345 Park Avenue
Madison, WI 53706, USA New York, NY 10154, USA
AL OWEN
Owen Associates Inc.
G S GARROW
251 Hilton Road
Clinical Research Centre
Westport, CT 06880, USA
Division of Clinical Investigation
Watford Road
D RALT
Harrow, Middlesex HA1 3UJ,
Department of Nutrition and Food
England
Science
Massachusetts Institute of
Technology
L GREEN 77 Massachusetts Avenue
Department of Nutrition and Food
Cambridge, MA 02139, USA
Science
Massachusetts Institute of S R TANNENBAUM
Technology Department of Nutrition and Food
77 Massachusetts Avenue Science
Cambridge, MA 02139, USA Massachusetts Institute of
Technology
77 Massachusetts Avenue
N JENKINS Cambridge, MA 02139, USA
Department of Oral Physiology
The Dental School S G SRIKANTIA
University of Newcastle-upon-Tyne Postgraduate Department of Food
Newcastle-upon-Tyne NE1 8ST, and Nutrition
England University of Mysore
Manasaga ngotri
Mysore 570012, India
T H JUKES
University of California J H YOUNG
Berkeley Department of History
RSSF, 1414 Harbour Way So. Emory University
Richmond, CA 94804, USA Atlanta, GA 30322, USA
vii
Preface
This new volume deals with a number of important and current topics in
human nutrition that we hope will be of general interest to those concerned
with this subject. We have first of all a chapter by J. S. Garrow and S. Blaza on
energy requirements, which has a direct bearing on the problem of obesity, and
which largely affects the populations of developed and afiluent countries. This
is followed by a chapter on fluoride and the fluoridation of water, under the
authorship of G. N. Jenkins. The addition of fluoride to drinking water has
given rise to a great deal ofd iscussion both amongst scientists and the public at
large, and the present account tries to give the scientific background and a
critical evaluation of established facts. The chapter by G. Owen on the
nutritional status of North Americans is also likely to be of interest to other
countries, as the techniques used and the problems encountered are similar to'
those encountered in other parts ofthe world. A chapter on nitrates, nitrites and
nitrosamines by S. R. Tannenbaum discusses a topic which again has
engendered widespread interest amongst a large number of people, and where a
balanced presentation of the relevant facts is particularly important. One of the
fields in which biochemistry, physiology and nutrition have made enormous
advances over the last few years is that of vitamin D and the new knowledge
acquired on control of the metabolism of calcium and phosphorus. This
information is critically discussed by H. DeLuca.
The developing world, which comprises the majority of mankind, has
always had its special nutritional problems, and these vary from country to
country. The problems chosen by S. G. Srikantia appear to be of special
importance, and these are vitamin A deficiency, protein energy malnutrition,
and pellagra. Whilst more knowledge is still required on many of these topics,
the chief difficulty is in applying existing knowledge to the complex social,
economic and political realities of the various countries concerned. We have
a chapter by J. Harvey Young who deals with nutritional eccentricities, also
choosing entirely American examples. This account emphasizes the different
problems facing scientists and others who are concerned with putting sound
nutritional advice to the population at large. These difficulties emphasize the
fact that human beings are not entirely rational and irrational considerations
play a large part in attitudes adopted by individuals and groups to many
problems, but particularly with respect to the diet people wish (or are
persuaded) to consume. In the last contribution one of us (T. H.Jukes )discusses
ix
HUMAN NUTRITION
the widespread use oflaetrile, a substance which has received much publicity,
especially in the USA. Several important topics in nutrition have not been
covered, but we have tried to deal with the fields which are of particular
importance at the present time.
Thomas H. Jukes
Albert Neuberger
x
1
Energy requi rements inhuman bei ngs
J. GARROW AND S. BLAZA
INTRODUCTION
A dietary source of energy must occupy a central place in any nutrition
scheme, since energy requirements must be met even at the expense of protein
requirements. However, dietary energy requirements are difficult to define in
anyspecies;al1d particularly so in human beings. The nutritional objective of
livestock farmers -is clear: tliey llave fo rruse their animals as profitably as
possible. For a given strain of pig, for example, a certain ration can be shown to
be optimum to yield the most meat at least cost, but such criteria do not apply
in human nutrition. The human nutritionist cannot play safe and recommend
aminimumofene!,gyin the diet. Itis possibletodefine'enough;yjtamin C, and if
tKe requirement is exceeded not much harm is done, but the same lati{ude does
not apply to energy intake." Grossly excessive and" grossly deficient energy
intakes are both damaging to health.
At least in the short term, there is no need for energy intake to match
expenditure, since a temporary excess or deficit can be met by adjustment of
the energy stores of the body, chiefly in the form of fat. In the long term, of
course, intake must match output, but alterations in the energy stores of the
body are themselves associated with alterations in metabolic rate, and hence in
energy requirements. Therefore, to discuss energy requirements it is necessary
to consider in turn energy expenditure, energy stores, and then the adaptive
responses which tend to stabilize energy balance.
Energy units
Until the change to SI (Systeme Internationale) units, human energy intake
and expenditure was usually expressed as kilogramme calories (kcal). The SI
unit is the joule (J), and the conversion:
1 kcal = 4.18 kJ
Since direct calorimeters are usually calibrated with respect to electrical
standards, the rate of heat output by direct calorimetry is expressed as watts:
1 watt = 1JI s, so 1 kcaljmin = 70 watts.
HUMAN NUTRITION
When energy expenditure is measured by indirect calorimetry, the heat
equivalent of the respiratory exchange can be calculated using the Weir
formula 1• However, a fundamental limitation of the accuracy of indirect
calorimetry is that the mixture of expired gases does not necessarily reflect the
metabolic mixture being produced in the tissues. CO may be stored in the
2
tissues, so the apparent RQ may not equal the metabolic RQ. For this reason it
is prudent to report the results obtained in indirect calorimetry in terms of
oxygen uptake, rather than converting to heat production using an assumed
value for the heat equivalent of oxygen which may not be correct. However, to
provide the reader with an easy conversion of oxygen uptake to energy
expenditure the following equation will suffice:
Oxygen uptake (mljmin) x 7 = kcal/day.
ENERGY EXPENDITURE
Techniques for measurement of energy expenditure
(a) Direct calorimetry
The classical studies on human energy expenditure were performed by
Atwater and Benedice with a direct calorimeter. This was a copper box 2.15 m
long, 1.22 m wide, and 1.93 m high. The subject entered through an aperture
49 em wide and 79 em high; the aperture was then sealed with a sheet of plate
glass embedded in molten beeswax. Great care was taken to ensure that there
was no heat gradient across the walls of the calorimeter, and the heat produced
but the imprisoned subject was exactly removed by careful regulation of the
flow of cold water through pipes inside the chamber. In the ensuing 70 years
there have been considerable advances3•4•s making calorimetry less arduous
for both the subject and the investigators, but the accuracy of the original
apparatus has not been surpassed. The great advantage of direct calorimetry is
its accuracy and ease of calibration. An electrical heat source, or a lamp
burning ethyl alcohol or butane, can be used as a reference standard, and the
observed heat production should agree with the theoretical value within 1 %6.
The qisadvantages of direct calorimetry are that it is expensive, laborious and
slow. The design of a relatively simple direct calorimeter?, which was
constructed by the Division of Bioengineering at the Clinical Research Centre
in 1976, is shown in Figure 1.
The calorimeter chamber (2m wide by 1.7m deep by 2m high) is
constructed of slabs of expanded polystyrene (P) 20em thick, faced on the
inner and outer surfaces with sheet aluminium. Access to the chamber is by a
door in which there is a pass-through hatch (H), with clear plastic panels
hinged in the inner and outer faces; this also provides a window. The chamber
is furnished with a bed, chair, table, small television set and radio-tape
recorder. The great majority of patients admitted to our metabolic unit are
quite willing to spend a period of 26 hours in this chamber on several
occasions.
The air inside the chamber (volume approximately 6m3) is circulated by an
axial fan (F) along a duct into a plenum chamber lOem deep covering the
2
ENERGY REQUIREMENTS
Figure 1 Diagram of the direct calorimeter at the Clinical Research Centre, Harrow. For
description see text
whole area of the right-hand wall of the chamber. The inner wall of this
chamber is made from perforated hardboard, so the air escapes into the
chamber and flows in a laminar fashion from right to left across the chamber
and enters a similar plenum chamber on the left-hand wall. From here it is
sucked down to the duct, where part of the stream of air passes through a heat
exchanger (X), and part bypasses the heat exchanger. The proportion of the
circulating air which is cooled in the heat exchanger is determined by the
position of the shutter (S), which is driven by a servo motor which is sensitive
to the temperature gradient across the walls of the chamber. Thus, if the
thermistors mounted on the inner and outer aluminium skins of the chamber
detect a new outward flow of heat across the walls, the servo motor is
instructed to move the shutter so a larger proportion of the circulating air is
cooled, and if the net movement of heat through the walls is inward the shutter
moves in the opposite direction to reduce the amount of heat extracted from
the circulating air. In this way the heat flow across the walls is kept close to
zero over any long period, so any heat produced by the subject in the
calorimeter is quantitatively extracted in the heat exchanger. Heat loss by
convection and evaporation is not separately measured, since evaporative heat
3
