EVERY woman who’s trying to get pregnant knows, or at least is supposed to
know, that folic acid supplements are a good idea. They will protect her baby
from developing spina bifida and other neural tube defects—rare diseases,
but ones that can cause devastating disability.
Now a study from Sweden has found that folic acid tablets have a curious
side-effect: they appear to make women more likely than usual to have twins
(see “Acid test”).
This may not seem important, until you realise that twins have an
increased risk of developing cerebral palsy and of dying in the womb or in the
months after birth. The researchers conclude that in some countries, especially
those where spina bifida is rare, the health risks of taking folic acid tablets
may be greater than those of not taking them.
Their suggestion comes three years after the US government made folic acid a
compulsory additive in foods such as cereals and wholemeal bread. The British
government is about to decide whether to fortify wheat flour with folic
acid.
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Many people balk at the idea of adding chemicals to water and
food—witness the distaste for adding fluoride to water. But researchers
argue that folic acid shouldn’t be so controversial. It is an essential vitamin
and there’s little evidence that folic acid supplements cause major health
problems. On the contrary, we could all benefit from taking more of it. Studies
suggest that we’re all deficient in the vitamin and this could be a factor in
cardiovascular disease.
But then up pops a link with extra twin births. The case has still to be
proved. The effect could come from some unseen confounding factor—and no
one is suggesting that would-be mothers should stop taking folic acid. In many
countries, even if the link is confirmed, the vitamin’s benefits will still
outweigh its disadvantages. But the study on twinning should remind us of a
hazard of preventive medicine: harm lurks in unexpected places. The implications
of the Swedish findings need swift investigation. If governments are going to
enforce the addition of chemicals to food, they must not relax their search for
harmful consequences.
