Nutrition Research Reviews (1998), 11, 115-131
Nutrition intervention strategies to combat zinc
deficiency in developing countries
Rosalind S. Gibson and Elaine L. Ferguson
Department of Human Nutrition, University of Otago, Dunedin, New Zealand
Widespread zinc deficiency is likely to exist in developing countries where staple
diets are predominantly plant based and intakes of animal tissues are low. The
severe negative consequences of zinc deficiency on human health in developing
countries, however, have only recently been recognized. An integrated approach
employing targeted supplementation, fortification and dietary strategies must be
used to maximize the likelihood of eliminating zinc deficiency at a national level
in developing countries. Supplementation is appropriate only for populations
whose zinc status must be improved over a relatively short time period, and when
requirements cannot be met from habitual dietary sources. As well, the health
system must be capable of providing consistent supply, distribution, delivery and
consumption of the zinc supplement to the targeted groups. Uncertainties still exist
about the type, frequency, and level of supplemental zinc required for prevention
and treatment of zinc deficiency. Salts that are readily absorbed and at levels that
will not induce antagonistic nutrient interactions must be used. At a national level,
fortification with multiple micronutrients could be a cost effective method for
improving micronutrient status, including zinc, provided that a suitable food
vehicle which is centrally processed is available. Alternatively, fortification could
be targeted for certain high risk groups (e.g. complementary foods for infants).
Efforts should be made to develop protected fortificants for zinc, so that potent
inhibitors of zinc absorption (e.g. phytate) present either in the food vehicle and/or
indigenous meals do not compromise zinc absorption. Fortification does not
require any changes in the existing food beliefs and practices for the consumer and,
unlike supplementation, does not impose a burden on the health sector. A quality
assurance programme is required, however, to ensure the quality of the fortified
food product from production to consumption. In the future, dietary modifica-
tion/diversification, although long term, may be the preferred strategy because it is
more sustainable, economically feasible, culturally acceptable, and equitable, and
can be used to alleviate several micronutrient deficiencies simultaneously, without
danger of inducing antagonistic micronutrient interactions. Appropriate dietary
strategies include consumption of zinc-dense foods and those known to enhance
zinc absorption, reducing the phytic acid content of plant based staples via enzymic
hydrolysis induced by germination/fermentation or nonenzymic hydrolysis by
soaking or thermal processing. All the strategies outlined above should be
integrated with ongoing national food, nutrition and health education programmes,
to enhance their effectiveness and sustainability, and implemented using nutrition
education and social marketing techniques. Ultimately the success of any approach
for combating zinc deficiency depends on strong advocacy, top level commitment,
a stable infrastructure, long term financial support and the capacity to control
Rosalind S. Gibson and Elaine L. Ferguson
quality and monitor and enforce compliance at the national or regional level. To be
cost effective, costs for these strategies must be shared by industry, government,
donors and consumers.
Micronutrient deficiencies are a widespread public health concern. Dietary inadequacies of
iodine, vitamin A, and iron are presently estimated to adversely affect the health, mental and
physical function, and survival of more than 2 billion people in the world, even though such
inadequacies have been documented for more than a decade. In contrast, the severe negative
effects of zinc deficiency on human health in developing countries have only recently been
recognized by the United Nations. Zinc was omitted from the United Nations (1991) micro-
nutrient priority list, in part because of a lack of awareness of the importance of zinc in human
nutrition; the nonspecific clinical features of zinc deficiency (i.e. impaired growth and immune
function, poor appetite and taste acuity); lack of a recognized sensitive and specific index of
zinc status; and finally a lack of data on the zinc and antinutrient content of local staple foods in
developing countries. In retrospect the omission of zinc from the United Nations micronutrient
priority list was very unfortunate because zinc deficiency in developing countries is likely to be
as prevalent as nutritional iron deficiency.
The first cases of human zinc deficiency, described in the 1960s, were male adolescents
from the Middle East consuming plant based diets containing high levels of antinutrients,
known to inhibit zinc absorption: intakes of flesh foods were low (Prasad ef al. 1963). This
dietary pattern is common not only in the Middle East but in many other developing countries.
During childhood, zinc deficiency causes stunting and impaired cognitive function and
increases the incidence and severity of acute and persistent diarrhoea, acute lower respiratory
infections, and possibly the incidence of malaria caused by Plasmodium falciparum (Ham-
bidge, 1997). In pregnancy, zinc deficiency may contribute to complications and low birth
weight (Tamura & Goldenberg, 1996). Additionally, some non-nutritional factors may
exacerbate any deficiency of zinc, and at the same time compromise iron status. These include
chronic intestinal blood loss through parasite infections such as hookworm (Stoltzfus ef al.
1997), chronic haemolysis induced by malaria and schistosomiasis (Williams & Naraqi, 1979),
and for women of child-bearing age, menstruation and frequent reproduction cycling (Halberg,
1992). Interactions with other micronutrients may result in zinc deficiency exacerbating other
micronutrient deficiency states (e.g. vitamin A ) (Udomkesmalee et al. 1990).
With the recognition of the impact of zinc deficiency on human health comes the need to
develop programmes to combat this deficiency, preferably by incorporating zinc into pre-
existing micronutrient intervention strategies. This review examines possible intervention
strategies to combat zinc deficiency in developing countries.
Three nutrition intervention strategies have been used with varying success to combat
deficiencies of vitamin A, iron and iodine: supplementation, fortification and dietary diversi-
fication/modification. These same strategies can also be designed to simultaneously alleviate
zinc deficiency with only a modest addition to the overall costs of the programme. Imple-
mentation of these strategies in developing countries requires the combined resources of
government, industry, public health educators, donors, scientists, nongovernmental organiza-
tions and consumers.
Zinc nutrition intervention strategies
In developing countries, supplementation programmes are expensive short term strategies that
rely heavily on donor support and individual compliance. They are only appropriate for
populations where the micronutrient status, such as the zinc status, must be improved over a
relatively short time period. Supplementation is appropriate when the requirements cannot be
met from habitual dietary sources (e.g. pregnant women, low birthweight infants, infants and
children with acute or persistent diarrhoea and those recovering from severe malnutrition).
Furthermore, a health system capable of providing a consistent supply, distribution, delivery
and consumption of the zinc supplement to the targeted group(s) is also required. All too often
supplementation programmes have failed because of poor compliance, poor coverage, absence
of commitment at the national and community levels and poorly designed communication
messages. Increased burden to already overloaded health care delivery systems may also be a
contributing factor (Gillespie et al. 1991).
More qualitative research is required to understand the complex reasons for poor com-
pliance in supplementation programmes. In iron supplementation programmes, poor com-
pliance has often been linked with the onset of side effects. However, behavioural barriers are
also implicated, especially during pregnancy when long term medication is thought to be
harmful to the baby or result in a bigger baby and therefore delivery difficulties (Galloway &
Zinc supplements can be given alone or as a component of multimicronutrient supplements
such as prenatal iron and folate. Care must be taken when formulating these multimicronutrient
supplements to use salts that are readily absorbed, and levels that will not induce antagonistic
interactions among major and trace elements. For zinc, possible interactions between zinc and
calcium (Wood & Zheng, 1997), zinc and non-haem iron (Solomons, 1986) and zinc and
copper (Yadrick et al. 1989; Fischer et al. 1984) should be considered.
When given alone, zinc supplements should be administered in the fasting or post-
absorptive state to avoid any dietary components interfering with zinc absorption (Oelshlegel &
Brewer, 1977). In contrast, multimicronutrient supplements should be consumed with food
because the presence of the ligands in food appears to minimize the inhibitory effect of non-
haem iron on zinc absorption (Valberg et al. 1984; Sandstrom et al. 1985; Walsh et al. 1994)
and vice versa (Crofton et al. 1989; Yadrick et al. 1989; Brown et al. 1997).
There are currently three major barriers to effective zinc supplementation programmes.
The first is the high frequency of the dose required. Most of the zinc in the human body exists in
nonlabile pools (e.g. muscle and bone) and is not normally released during zinc deprivation
(Aggett & Comerford, 1995). Furthermore, daily rather than intermittent doses of zinc were
required to produce a body growth response that fully compensated for a previously deficient
zinc intake in rats (MomciloviG, 1995). Hence, unlike iron supplements, weekly or twice
weekly doses may not be as effective as smaller doses given daily. Bates et al. (1993) gave
70 mg zinc as zinc sulphate twice weekly for 1.25 years in a double-blind zinc supplementation
study of Gambian infants but did not observe any significant effect of the zinc supplement on
biochemical indices of zinc status. Small changes in arm circumference, an improvement in
urinary 1actulose:creatinine molar ratio (an index of intestinal permeability) and a trend
towards fewer malaria episodes were observed.
Secondly, uncertainty still exists about the best type of zinc salt to use in relation to
bioavailability and side effects. Both salt-solubility-dissolution and intragastric pH are known
to influence oral zinc absorption (Sturniolo et al. 1991). Human studies of zinc absorption from
zinc ascorbate, methionine, histidine, citrate, gluconate, picolinate, oxide and aminoate, mea-
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