F&N Bulletin Vol 23 No 1b - United Nations University

Special Article
Nuclear and isotopic techniques for addressing
nutritional problems, with special reference to current
applications in developing countries
Venkatesh Iyengar
Abstract
Nuclear and isotopic techniques are valuable tools in
human nutritional research studies. Isotopes, both radioactive
and nonradioactive, enable detailed evaluations of
nutrient intake, body composition, energy expenditure,
status of micronutrients, and nutrient bioavailability. In
recent times, isotopic methods have been widely used in
a number of coordinated research projects and technical
cooperation projects of the International Atomic Energy
Agency’s Nutrition Programme. The doubly labeled
water technique combines the use of the stable isotopes
oxygen-18 and hydrogen-2 (deuterium) to measure
total energy expenditure in free-living human subjects,
and to investigate the magnitude and causes of both
undernutrition and the emergence of obesity in developing
countries. The deuterium dilution technique is a
reliable tool to measure breastmilk intake and thereby
infant growth and development. In collaboration with
the World Health Organization’s Growth Monitoring
Program, this technique is being used to generate new
data on growth standards for children in developing
countries. This technique is also used in the measurement
of body composition by the estimation of lean body mass
and fat mass in individuals. Stable isotopes of iron and
zinc have been successfully used to assess the nutritional
impact of several nationwide food supplementationprograms
conducted on pregnant and lactating women
and children in both industrialized and developing
countries. Isotopic techniques are especially suitable
for monitoring changes in body composition, energy
metabolism, and mineral status (with particular reference
to osteoporosis) in the elderly. Nuclear methods have
also served to develop models for a physiological reference
man in Asia in support of radiological health and safety
issues, for establishing elemental composition of foods,
and for measurement of pollutants in the environment.
The author is the Head of Nutrition and Health Related
Environmental Studies at the International Atomic Energy
Agency in Vienna, Austria.
Global nutritional challenges
Hunger and undernutrition are among the most devastating
problems facing the majority of the world’s
poor and needy. Several United Nations conferences
on food and nutrition have highlighted this situation
and the need to eliminate poverty and undernutrition,
especially among women and children [1–3]. Each
year 30 million infants in the developing world are
born with intrauterine growth retardation, leading to
low weight at birth. This represents about 24% of the
births in these countries. Nearly 200 million children
(more than 150 million in Asia and about 27 million
in Africa) under five years of age are moderately to
severely undernourished, while 70 million are severely
undernourished. There are projections that about
one billion children will be growing up by 2020 with
impaired mental development [4, 5].
Around 243 million adults in developing countries
are reportedly undernourished (body mass index of
less than 18.5 kg/m 2 ), resulting in lowering of their
work capacity and resistance to infection. Maternal
anemia is pandemic, with a prevalence over 80% in
some countries, and is associated with very high rates
of maternal mortality. Evidence from both developing
and industrialized countries links maternal and early
childhood undernutrition to increased susceptibility to
diabetes, heart disease, and hypertension in adult life.
A fundamental link is emerging between maternal and
childhood malnutrition and the child’s subsequent
marked sensitivity to abdominal obesity, diabetes, high
blood pressure, and coronary heart disease [6]. Added
to this is the burden of overnutrition and obesity that
is rapidly emerging in the same developing countries,
affecting both children and adults.
Since the early 1990s, there has been a shift in concern
from overt clinical nutritional deficiencies (e.g.,
protein and energy malnutrition or extremely severe
vitamin deficiencies) to so-called hidden or silent
hunger or micronutrient malnutrition, a symbol of
persistent undernutrition [7]). According to global
estimates, some two billion people in more than 100
Food and Nutrition Bulletin, vol. 23, no. 1 © 2002, The United Nations University. 3