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Archived Comments for: Vitamin and mineral supplements in pregnancy and the risk of childhood acute lymphoblastic leukaemia: a case-control study

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  1. Population level folate supplementation

    Kenneth Campbell, Posted in private capacity

    9 August 2007

    Dockerty at. al. report findings differing from those of the Australian 2001 study which reported a protective effect of folate supplementation against childhood ALL. Dockerty and his co-authors point out several of the difficulties of retrospective case-control studies of factors such as dietary supplementation.

    In North America (USA and Canada) mandatory folate supplementation of a range of foodstuffs was introduced in the late 1990s. De Wals et al (1) report a reduction in incidence of neural tube defects in Canadian neonates following supplementation. The impact of folate supplementation strongly suggests that self-administration of folate during pregnancy was not occurring at high levels throughout the study population. A greater benefit was seen in populations with a higher baseline rate - this suggests a difference in baseline incidence relative to how folate replete that population was prior to supplementation.

    It may be informative to examine the incidence of childhood leukaemia in the North American populations prior to and subsequent to mandatory supplementation. Changes in rates of neural tube defects in the same populations would indicate whether pregnant women within these populations were folate replete prior to supplementation. If they were not and folate is protective, one might expect to see changes in the trend of childhood ALL incidence - given the gradual increase being observed in most populations, there may not be a decrease in incidence but a change in the slope of increase would be persuasive evidence.

    1. De Wals, P., Tairou, F., Van Allen, M. I., Uh, S.-H., Lowry, R. B., Sibbald, B., Evans, J. A., Van den Hof, M. C., Zimmer, P., Crowley, M., Fernandez, B., Lee, N. S., & Niyonsenga, T. 2007, "Reduction in neural-tube defects after folic acid fortification in Canada", NEJM, vol. 357, no. 2, pp. 135-142.

    Competing interests