March 21, 2018

expert reaction to low maternal vitamin D levels in rats and neurodevelopment and social behaviours in male offspring

A new study, published in Journal of Endocrinology, examines vitamin D consumption during pregnancy and breast feeding and potential development of autism-like behaviour.

A Before the Headlines analysis accompanied this roundup.

Prof Martin Hewison, Society for Endocrinology member, & Professor of Molecular Endocrinology, University of Birmingham said:

“This is not the first study to show that vitamin D-deficiency during pregnancy can influence the health and behaviour of offspring and, although it is conducted in rats, it does provide a clearer picture of how this occurs. Specifically, the authors demonstrate effects of vitamin D deficiency on both mother and child. They show that the vitamin D-deficient mothers spent less time grooming their pups than vitamin D-sufficient mothers. Likewise, in the male pups, they describe profound changes in brain development that result in behaviour consistent with autism spectrum disorder. The overall conclusion from this study is that vitamin D deficiency early in pregnancy may have a detrimental impact on the health of children.

“Of course the rats used in this study had received no vitamin D for several weeks before mating, so their levels of vitamin D during pregnancy were very low. However, low levels of vitamin D are increasingly reported for pregnant women, particularly in northern countries such as the UK. Further work is now required to determine if vitamin D supplementation during pregnancy can ‘rescue’ offspring health. At the moment, vitamin D supplementation in humans is usually not started until the end of the first trimester of pregnancy (approximately week 12). However, this may be too late to reverse the offspring brain development changes observed in the current paper. Future studies will also need to determine how much vitamin D supplementation is required during pregnancy. At present the UK Science Advisory Council on Nutrition (SACN) recommendations for pregnant women are 400 IU/day (10 micrograms/day), but it is unclear whether this will have any benefits for the neurological and behavioural changes described by Yates et al in the current Journal of Endocrinology paper.”

Prof Dorothy Bishop, Professor of Developmental Neuropsychology, University of Oxford, said:

“Contrary to the title of the press release, this study is not about autism in children. The experiment was designed to consider the impact on the offspring of vitamin D deficiency in pregnant rats. An enormous number of measures were taken: of behaviour of mothers and offspring, of gene expression, and brain regions. When doing a study with so many outcomes, it is essential to control for the number of statistical comparisons to avoid obtaining spurious effects. Unfortunately this was not done. Furthermore, the reporting of data was not sufficiently detailed to be clear what was done, but there appear to have been some basic errors in statistical analysis, treating multiple measures on individual rats as if they were independent. This, coupled with data dredging in a large dataset, makes me lack confidence in the results in rats, let alone the extrapolation of the findings to humans.”

* ‘Vitamin D is crucial for maternal care and offspring social behavior in rats’ by Yates et al. published in Journal of Endocrinology on Wednesday 21 March.

Declared interests

Prof Martin Hewison: No conflicts of interest

Prof Dorothy Bishop: “I declare I have no conflict of interest”