Using modern sophisticated stable isotope techniques, Mishaan et al have
clearly demonstrated bioavailability of iron and zinc from a multiple
micronutrient-fortified beverage in 6- to 9-year-old Peruvian children.1
Absorption of iron was in the range of 10% whether the beverage was ingested
with food or between meals, and absorption of zinc was ~23% independent of the
concurrent ingestion of food. The results of the study are important because
this fortified beverage provides another option for preventing iron and zinc
deficiencies.
The international focus on prevention of iron deficiency is not surprising2;
iron deficiency is the most prevalent nutritional deficiency in the world today,
and through its impact on the myelination of the developing central nervous
system, infants and young children with iron deficiency are likely to manifest
impaired motor, cognitive and socio-emotional development. When these children
enter school, they are more likely to fail grades and manifest behavioral
problems. Moreover, the economic impact in adults, due to cognitive losses in
childhood, is not trivial when considering the challenges faced by many
developing countries. In fact, recently published estimates of the worldwide
economic impact of childhood iron deficiency suggest a reduction of 4.5% of GDP
through reduced learning and ultimately poorer paying jobs.3
In many developing countries, the prevalence of iron deficiency is as high as
80%, therefore the biologic, social, and economic impacts are immense.
Although the extent of zinc deficiency is harder to quantify, it is likely
found in combination with iron deficiency and affects the body’s immunologic
defenses. Zinc supplementation in children with zinc deficiency decreases the
morbidity associated with diarrheal diseases and pneumonia.4
Because of the biologic importance of these two micronutrients, there is both
national and international emphasis in prevention of deficiencies.2
From a public health perspective, there are four potentially successful
approaches for the prevention of micronutrient deficiencies. These include
recommendations for dietary diversification to increase the intake of foods
containing bioavailable sources of iron (eg, red meat, fish, and poultry),
fortification of commodity-type foods (eg, wheat flour), use of dietary
supplements, and targeted fortification. In Canada and the United States, we use
a combination of strategies. For example, the food pyramid recommends the
ingestion of a mix of foods from food groups including meat and poultry (both
good sources of iron), wheat flour and products made from wheat flour (eg,
pasta) that are fortified, breakfast cereals that are highly fortified, and
targeted foods for infants (eg, infant cereals and formulas) that are highly
fortified at levels designed to meet their specific micronutrient needs. In the
developing world, however, especially for infants and young children, most of
these options are not feasible. Meat, poultry, and fish are among the most
expensive foods to purchase, so for the majority of at-risk families, this
intervention is not an option. Although the fortification of food commodities
like wheat flour is inexpensive, it too is unlikely to work with infants and
children because the level of fortification is aimed at an adult population and
the amount of food children eat is simply too small (compared with adults) to
make an impact. Finally, targeted fortification (such as the use of infant
cereals and fortified formula) is not successful because breast-feeding is
recommended and practiced (appropriately) in most developing country settings
and commercial infant foods are both too expensive and culturally unacceptable.
Thus, from a public health perspective, one has to turn to nontraditional
sources of micronutrients, like fortified beverages or home-fortification.5
Although Mishaan et al clearly demonstrate the biologic availability of the
micronutrients from the fortified beverage, a more important practical issue
that was not adequately addressed was the potential use of this new fortified
commercial product in populations at highest risk for iron and zinc deficiency.
Children between the ages 6 and 9 years are not at high risk because growth (and
growth in blood volume) is not particularly rapid. For example, had the authors
completed this study in adolescent females, a high-risk population, the results
would have been even more important. In the pediatric age range, infants 6 to 24
months of age and adolescent girls are at greatest risk of deficiency. Infants
in the developing world are at risk for a number of reasons: (1) many are born
with low stores because of maternal anemia; (2) early cord clamping impacts on
iron endowment; (3) blood volume doubles in the second 6 months of life; (4)
prolonged exclusive breast-feeding fails to meet iron and zinc needs; (5)
chronic infection impacts food intake, parasitic infections lead to blood loss
in stool; and (6) typical home-made complementary foods are poor sources of
iron. Adolescent girls are at risk because of rapid growth (and increase in
blood volume), menstrual blood loss, parasitic infection (with gastrointestinal
blood loss) and iron-poor diets. But children between 6 and 9 years old do not
fall into either of these high-risk categories.
The availability of medicinal or food products to solve the problem of iron
and zinc deficiency is not really the issue. For example, iron drops are
inexpensive and have been widely available for the past 150 years. Yet there is
no documentation of successful, long-lasting iron deficiency prevention programs
associated with their use. There are a number of reasons they have not been
successfully used, including their strong medicinal taste, the staining of an
infant’s teeth with their use, and difficulty in measurement of doses. The real
issue is finding a supplement or fortified food that is both efficacious and
effective, meaning that it works to prevent the deficiency, is affordable,
acceptable, and sustainable. Although Mishaan et al have clearly demonstrated
the bioavailability of the minerals in the multimicronutrient beverage, the next
step is the real challenge. If it is going to be used in populations at risk,
such as adolescent girls or women in the childbearing age, how will it be
distributed? And will those really in need choose to buy it and be able to
afford it? Certainly a protein-free sugar drink, even one with micronutrients
would not be appropriate for young infants. For adolescents, a sweet
noncarbonated multimicronutrient fortified beverage would likely be quite
acceptable. However, with very limited spending money, would an adolescent
choose to buy it? Probably not.
Iron deficiency has been characterized by the World Health Organization as
one of the top 10 serious health problems in the modern world.2
Zinc deficiency, too, is a major contributor to childhood morbidity and
mortality. The solution to these massive problems will have to be creative,
comprehensive and sustainable, and where possible, based on good science.
Mishaan et al have provided the good science. Who will provide the
rest?
