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A bridge too near
By Alfred Sommer
Dr. Alfred Sommer is Professor and Dean at the School of Hygiene and Public
Health, Johns Hopkins University, Baltimore. He has been in the forefront of
research into vitamin A deficiency for almost 20 years, and led the two major
Indonesian studies described in this article.
For almost a decade, medical science ignored or rejected the evidence that
vitamin A could reduce child deaths by between a quarter and a third in many
countries of the developing world.
Today, the scepticism of the 1980s has been swept away by an avalanche of data.
And as the tables on the following pages show, most nations are now moving to
make this most cost-effective of all health interventions available to their
children.
If this effort succeeds, then we can expect to bring about a fall in child
deaths of somewhere between 1 million and 3 million per annum.
Discovered in 1913, vitamin A has taken almost a century to come into its
own. It has long been known that the lack of this particular vitamin could
cause stunting, infection, and blindness in animals. But it was 1974 before the
first report was published (by WHO) on vitamin A deficiency as a major cause of
blindness among the children of the developing world.
Missing the point
In that same year, a research project was launched in Indonesia to find out
more about vitamin A deficiency, and particularly about what levels of
deficiency were associated with xerophthalmia (the inflammation and drying of
the eye that can result in permanent blindness). Over a period of a year and a
half, 4,000 children were examined at three-month intervals.
By 1981 much useful information had been gleaned. But in looking only for
what we expected to see, we had missed what the data itself had revealed.
Unlooked-for and unseen amid the mass of figures was a much more dramatic
message.
One December evening almost a year later, while a particular set of figures
was being cross-tabulated, it became apparent that many xerophthalmic children
were missing from later cross-tabulations. Running the computer analysis in the
reverse direction revealed what the data had been waiting to tell us all along:
children with even mild xerophthalmia were dying at a far greater rate.
Any suggestion that the higher death rate was caused by malnutrition, of
which the lack of vitamin A was merely a symptom, was quickly dispelled.
Malnutrition clearly increases the risk of child death, but so does vitamin A
deficiency - even among adequately nourished children. In fact the Indonesian
study showed that malnourished children with adequate vitamin A were less
likely to die than well-nourished children who were deficient in vitamin A.
Preliminary calculations, soon to be revised upwards, showed that if
xerophthalmia could be prevented, then the death rate among children aged one
to six would fall by approximately 20%. Analysis also showed that the risk of
death was directly related to the degree of deficiency.
To test these extraordinary conclusions, a second Indonesian study was
launched. This time, vitamin A capsules were given every six months to approximately
20,000 young children in 450 randomly chosen villages. The result was a
one-third reduction in death rates, compared with villages where there had been
no intervention.
These findings were published in The Lancet and other medical
journals. The response was the long silence of disbelief.
With its vision fixed on the high-tech and high-cost frontiers of modern
medical care, the medical and research establishment found it difficult to
accept that something as simple and cheap as a 2-cent capsule of vitamin A
could represent such a break-through for human life and health. Perhaps in some
quarters, also, there was an innate and ideological dislike of `magic bullet'
solutions to health problems which do not directly address the underlying
problems of poverty.
Whatever the reason, a discovery that seemed to promise so much had caused
barely a ripple on the surface of medical interest.
It was at this point that a wise colleague pointed out that this was the
normal first reaction to any unexpected research finding. The next stage, he
advised, was to "bury them in data."
Knowing that measles often leads to vitamin A loss, we had begun to wonder
if Africa's high death rates from measles might also be connected with vitamin
A deficiency. To test this, children hospitalized with measles in Tanzania were
given vitamin A capsules. The measles death rate fell by half. It was at this
point that we discovered, to our astonishment, that a similar experiment had
been conducted 50 years earlier in a London hospital - with the same results:
medicine too has doors it did not enter, paths it did not take.
WHO and UNICEF now acted quickly to make vitamin A supplementation a routine
part of measles treatment. More broadly, the elimination of the deficiency
became one of the goals adopted by the World Summit for Children held at
UNICEF's instigation in the fall of 1990. The progress being made towards that
goal is shown in the following tables.
By 1992, the results were in from several large, community-based
investigations into vitamin A deficiency. Ghana, India, Indonesia, and Nepal
all yielded results in line with the one-third reduction in mortality rates
revealed by the original research in Indonesia.
At this point, the medical community accepted our conclusions as unanimously
as it had dismissed them a decade earlier. A colleague who had earlier written
a leader in The New England Journal of Medicine titled `Too good to be
true', now published a paper under the heading `Too good not to be true'.
With the scientific community in full agreement, ministries of health across
the world have now given the green light to vitamin A supplementation.
Unfortunately, official recommendations usually stress vitamin A
supplementation only where there is evidence of severe deficiency, whereas the
evidence suggests that supplementation can significantly reduce mortality even
among populations with mild vitamin A deficiency. Further studies are now
needed to quantify this effect.
Three ways
Increasing vitamin A intake can be achieved by three main methods -
improving diets, fortifying common foods, and distributing vitamin A capsules.
The politically correct method is dietary improvement through the addition
of green leafy vegetables or carrots. Of course diets should be improved. But
this is a slow and uncertain process, and there are doubts about whether it can
provide sufficient vitamin A even where dietary change is indeed achieved.
Certainly, more work is needed on the most effective dietary ways of beating
vitamin A deficiency.
Some countries, particularly in Central America, have fortified sugar with
vitamin A (the problem was solved in the industrialized world by adding vitamin
A to common foods such as milk, bread, and margarine). But in the developing
world as a whole, food fortification is only beginning to be explored.
In the meantime, at least two children are dying every minute for the lack
of the protection that vitamin A can bring.
The 2-cent capsules are therefore an essential weapon for the defence of
children. And the outreach systems which have been built or strengthened by the
immunization effort of the last decade have now made it possible to deliver
that protection to the great majority of children at risk.
There can be no excuse for further delay.
ALL
INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR
GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE
KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED
AS PROVIDING MEDICAL OR LEGAL ADVICE. THE DECISION WHETHER OR NOT TO
VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU
ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.