The value of food fortification as a public health intervention

The Editorial by Harvey and Diug1 on the value of food fortification as a public health intervention was prompted by demonstration of the effectiveness of mandatory iodine fortification in reducing iodine deficiency.2 Mandatory fortification of wheat flour for bread making was introduced in Australia at the same time to prevent neural tube defects. Harvey and Diug state that the two are conceptually different, as the former addresses a population iodine deficiency, whereas folic acid fortification is to compensate a presumed genetic defect that cannot be individually recognised, thus raising ethical questions about exposing the many for the benefit of the few. However, this is the case in almost all public health interventions. Using an example of Harvey and Diug, we expose the whole population to the mandatory fortification of flour with thiamine to prevent Wernicke–Korsakoff syndrome, a condition largely confined to people with a chronic alcohol problem.

The concern they raise about mandatory folic acid fortification1 is exposure to unmetabolised folic acid, proposed as possibly increasing adverse effects, but which have not been clearly or conclusively shown. They refer to an Irish study reporting that seven of the 68 children in the study had detectable levels of unmetabolised folic acid in their blood.3 Ireland does not have mandatory folic acid fortification; the main sources of folic acid were voluntarily fortified breakfast cereals and fortified milk — products that are fortified with relatively high levels of folic acid. In Australia, breakfast cereals and other food products are also permitted to be fortified voluntarily — breakfast cereals often contain around 200–300 μg of added folic acid per 100 g (or about 100 μg per serve). This compares with mandatory fortification of flour of 200–300 μg per 100 g flour, or about 40 μg folic acid per slice of bread. While either source could lead to circulating unmetabolised folic acid, the higher doses in voluntarily fortified products are more likely to do so. With the introduction of mandatory fortification, there was a reduction in neural tube defects.4 Importantly, there has been a 68% reduction in previously higher rates of neural tube defects in Indigenous people.5 Mandatory fortification provides a more equitable, consistent and cheaper source of folic acid to the population than voluntary fortification. Let’s leave mandatory folic acid fortification preventing neural tube defects in our population.