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www.thelancet.com/lancetgh Vol 3 September 2015 e
Vitamin A deﬁ ciency: slow progress towards elimination
Gretchen Stevens and colleagues’ study1 in The Lancet
Global Health analyses 134 reports from 83 countries
of population-representative data for serum retinol
concentration and shows several trends in vitamin A
deﬁ ciency. First, prevalence is diminishing in a statistically
signiﬁ cant way in east and southeast Asia and Oceania.
Second, Latin America and Caribbean nations might be
making progress. Third, prevalence remains unchanged
in sub-Saharan Africa and south Asia. Stevens and
colleagues’ most interesting conclusion is that this
“evidence for both prevalence and absolute burden of
vitamin A deﬁ ciency should be used to reconsider, and
possibly revise, the list of priority countries for high-dose
vitamin A supplementation”.
However, several caveats need to be considered,
including the use of cross-sectional data, exclusion of
children younger than 6 months, absence of clinical
vitamin A deﬁ ciency assessments, gaps in serum retinol
data for certain populations and for 55 countries, use
of mortality data from randomised controlled trials of
vitamin A supplementation for diarrhoea and malaria
rather than population-level data, the assumption
that all post-neonatal measles deaths occur in children
aged 6–59 months old, and use of serum retinol as the
biomarker of deﬁ ciency.
Nonetheless, we might need to focus on retinol
concentration not mortality to assess and guide
our eﬀ orts to eliminate vitamin A deﬁ ciency, as
recommended by WHO for population-level surveys,
even though this measure can be problematic in
individuals because of the well known eﬀ ects of acute
inﬂ ammation due to infection or injury on serum retinol
concentrations.2 Controlling for acute inﬂ ammation
by including biomarkers for it3 might not be necessary
at the population level, because adequate vitamin A
status might, by itself, diminish inﬂ ammation through
a reduction in the frequency or severity of infections in
Despite these limitations, the authors provide
important estimates, with uncertainty distributions,
for the prevalence of vitamin A deﬁ ciency, and a clear
picture of trends from 1991 to 2013. The association
between vitamin A deﬁ ciency and eye pathology and all-
cause mortality is well known, as is the contribution of
vitamin A deﬁ ciency to reduced resistance to infections,
especially diarrhoea and measles, and increased mortality
in children younger than 5 years.4 These beneﬁ ts have
driven the scale-up of vitamin A supplementation
programmes as preventative public health measures
around the world. However, the coverage of these
programmes has not been eﬃ cient in east or southern
Africa (67%) and south Asia (53%).5 Lagging coverage
and continued evidence of vitamin A deﬁ ciency is the
basis for the suggestion by Stevens and colleagues that
future eﬀ orts refocus on these regions. This suggestion
makes sense if we are conﬁ dent that progress elsewhere
would not be compromised as a result.
During the past two decades, mortality from
diarrhoeal disease has substantially decreased and
measles has been eliminated as a public health issue
wherever eﬀ ective immunisation programmes ﬂ ourish.
Continued eﬀ orts to control diarrhoeal disease and
enhance measles vaccine coverage per se suggest
that vitamin A supplementation programmes should
now focus on the reduction of deﬁ ciency rather than
diarrhoea or measles morbidity or mortality as the
What then should be done to accelerate progress
towards elimination of vitamin A deﬁ ciency in children?
Initiation of supplementation programmes where
they do not exist and strengthening of programmes
where coverage is poor is step one. However, high-dose
supplementation only provides protection from hypo-
retinolaemia for 2–3 months in children younger than
5 years and favourably shifts the distribution of serum
retinol for less than 2 months,6 indicating that biannual
supplementation is not suﬃ cient by itself to prevent
vitamin A deﬁ ciency. Improvement of dietary intake of
foods rich in vitamin A (eg, animal products) or beta-
carotene is a more sustainable solution, but high-cost,
access, and cultural dietary practices have restricted
its potential to alleviate vitamin A deﬁ ciency. Other
options have been tested or are under development,
such as fortiﬁ cation of centrally processed foods
(although these might not reach poor populations in
rural areas); addition of vitamin A sprinkles to food in
the home, day-care centres, and schools;7 promotion of
beta-carotene rich foods such as sweet potatoes;8 and
genetically engineered crops with high concentrations
of beta-carotene such as golden rice.9 By addressing
See Articles page e528
www.thelancet.com/lancetgh Vol 3 September 2015
gaps in vitamin A suﬃ ciency around the world,
redirecting attention to areas of the world struggling
to make progress while continuing to monitor other
regions through systematic population-representative
sampling of serum retinol, promotion of research into
sustainable dietary solutions including a campaign to
legitimise genetically modiﬁ ed crops high in vitamin A
or precursors, and alignment of all of these eﬀ orts with
Sustainable Development Goal 2 to “end hunger, achieve
food security and improved nutrition and promote
sustainable agriculture”,10 we can not only sustain the
favourable trends described by Stevens and colleagues
but also hasten progress in other parts of the world.
*Davidson H Hamer, Gerald T Keusch
Center for Global Health and Development, Boston University
School of Public Health (BUSPH), Boston, MA 02118, USA (DHH);
Department of Global Health, BUSPH, Boston, MA, USA (DHH);
Section of Infectious Diseases, Department of Medicine, Boston
Medical Center, Boston, MA, USA (DHH, GTK); Tufts University
Friedman School of Nutrition Science and Policy, Boston, MA, USA
(DHH); and National Emerging Infectious Diseases Laboratories,
Boston University School of Medicine, Boston, MA, USA (GTK)
We declare no competing interests.
Copyright © Hamer et al. Open Access article distributed under the terms of
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vitamin A deﬁ ciency in children in 138 low-income and middle-income
countries between 1991 and 2013: pooled analysis of population-based
surveys. Lancet Glob Health 2015; 3: e528–36.
2 Thurnham DI, McCabe GP, Northrop-Clewes CA, Nestel P. Eﬀ ects of
subclinical infection on plasma retinol concentrations and assessment of
prevalence of vitamin A deﬁ ciency: meta-analysis. Lancet 2003;
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traditional measures of micronutrient status in rural Zambian children
during a randomized, controlled feeding trial. J Nutr 2014; 144: 972–78.
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