A growing incidence of severe birth defects among Irish newborns is being linked to a reduction in the amounts of folic acid added by food manufacturers to their products. The increasing preference of Irish consumers for discount retailers, which stock few products fortified with folic acid, may also be contributing to the rise in children born with neural tube defects, researchers have found.
The number of fortified products in each food group has dropped sharply in the past decade, the study published in the Journal of Public Health found, even though the level of fortification has increased in those products to which folic acid is still added.
Breads, cereals, fruit juices, spreads and yogurts are among the products less likely to contain added folic acid, according to researchers from Dublin City University and University College Dublin. Products that are still fortified tend to be in the niche "super/mega/vitamin-enriched" category.
It has long been known that folic acid, when taken before and during pregnancy, prevents the occurrence of most forms of neural tube defects such as spina bifida. In more than 50 countries, governments oblige food manufacturers to fortify products but in other countries, including Ireland, the addition of folic acid is voluntary.
Ireland used to have more widespread voluntary fortification than other European countries, and the rate of birth defects fell up to 2008. However, it started rising again in 2009, with some researchers suggesting economic hardship caused by the recession had affected the quality of food bought by low-income families.
In the current study, scientists audited the folic acid content of common foodstuffs in 2004, 2008 and 2014. The proportion of breads that were fortified fell from 17 per cent in 2004 to 2 per cent last year; the figure for fruit juices dropped from 67 per cent to 24 per cent, while spreads declined from 50 per cent to 13 per cent.
There were also large differences in the number of fortified products in different supermarket chains. The study found only a "minimal selection" of such products in discount stores; two in Lidl and 17 in Aldi. This compares to more than 100 in other chains; these, however, sell a wider range of goods.
The Food Safety Authority has considered introducing a system of mandatory fortification but decided in 2013 that no additional benefits would accrue from such a policy.
Researcher Frances Kelly of DCU said the voluntary system for fortifying foods left it up to consumers to track their consumption by checking food labels. "The impact on women of reproductive age who do not actively take folic acid supplementation before and during the early stages of pregnancy is potentially immense in terms of birth outcomes."