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expert reaction to pilot study on inositol plus folic acid in pregnancy, and neural tube defects

Publishing in the British Journal of Nutrition a group of scientists have examined the effect of inositol on using folic to prevent neural tube defects.


Title, Date of Publication & Journal

‘Inositol for prevention of neural tube defects: a pilot randomised controlled trial’ by Nicholas D. E. Greene et al published in the British Journal of Nutrition at 00:01 UK time on Friday 5 February 2016.


Study’s main claims – and are they supported by the data

This paper cannot prove that inositol when taken alongside folic acid in pregnancy is beneficial in preventing neural tube defects (NTDs) in babies, and the study is not able to support the suggestion in the press release that women may benefit from taking inositol, because the numbers are very small and there was no statistically significant difference in outcomes of women taking just folic acid or taking folic acid plus inositol.

The aim of the study, as clearly stated in the paper, was as a pilot study to investigate how difficult it may be to recruit participants to a further study, and to look at the safety of the supplement.




The sample size of the study is very small – 99 women were eligible, but only 47 were randomised.  So only 47 women took part in a randomised trial.

The event rate (number of cases of NTDs) was also very small – one in the randomised section of the study, and two in the non-randomised section.

Page 19 of the study notes that urine assays of inositol concentration revealed high inter-subject variability, which the authors attribute to non-compliance with the study protocol.  This makes the study even less conclusive.


The study was designed to establish how feasible it is to recruit pregnant women to these trials, to get an idea of how large a future trial would need to be, and to determine whether inositol is safe and whether it is associated with any side effects. The study has certainly reported some interesting findings in those respects, including that it may be difficult to recruit women to a randomised study in this area. The study also reported no adverse effects of the supplementation protocol.



NTDs = neural tube defects.


‘Inositol for prevention of neural tube defects: a pilot randomised controlled trial’ Nicholas D. E. Greene et al. published in the British Journal of Nutrition on Friday 5 February 2015. 


Before The Headlines is a service provided to the SMC by volunteer statisticians: members of the Royal Statistical Society (RSS), Statisticians in the Pharmaceutical Industry (PSI) and experienced statisticians in academia and research. A list of contributors, including affiliations, is available here.

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