December 5, 2023

expert reaction to study suggesting many pregnant women may not be getting essential nutrients they need from modern diets

A study published in PLOS Medicine looks at nutrient status in pregnant women. 

Dr Duane Mellor, Registered Dietitian and Senior Lecturer, Aston Medical School, Aston University, said:

“This is an interesting study which explores the effects of a nutritional supplement on blood levels in pregnancy in a randomised controlled study which recruited women in the UK, Singapore and New Zealand.

“It suggests that women and their babies might be at risk due to dropping levels of vitamins (especially vitamins B6, B12 and D) and minerals (especially iodine) during pregnancy, and although some of this drop might be explained by an increase in the amount of blood (plasma) which expands during pregnancy, the authors claim that the drop in levels may represent a level of deficiency. However, this paper does not actually report any health changes experienced during pregnancy or how healthy the babies were when they were born.

“It is also interesting that a number of the researchers were co-inventors with Nestle for the supplement used in the study, which contained not only B vitamins, vitamin D, zinc and iodine it also contained moo-inositol and probiotic bacteria. It might be seen as a potential conflict of interest that the researchers are co-inventors of the supplement with a large multi-national food company. This concern might be increased given unlike earlier studies of vitamin supplements which showed folic acid (folate) reduced the risk of spina bifida and neural tube defects, this study did not show any benefits for the mother or baby, this might be part of a later publication?

“It is important during pregnancy to eat a healthy and varied diet, it is generally recommended to seek sources of folate (especially during the first 12 weeks as it has been shown to reduce the risk of spina bifida and other defects of the neural tube), vitamin D and iodine. These can be obtained from foods which might be fortified or in supplements, but it is important not to take too much of any one vitamin or mineral as high doses of some can be potentially harmful, especially vitamin A. So, apart from folic acid (folate) which has recommended doses of 400 micrograms a day for most women, it is not recommended to take more than the recommended daily amount of any other vitamin or mineral.”

Prof Ian Givens, Professor of Food Chain Nutrition, Director, Institute for Food, Nutrition and Health, University of Reading, said:

“This study is very timely and should provide the impetus to reassess dietary provision of key nutrients before and during pregnancy. In UK omnivores, dairy foods, meat and fish provide about 80% of dietary vitamin B12 and meat, eggs and fish provide about 65% of dietary vitamin D although dietary supply only provides about 3 micrograms per day meaning that supplementary vitamin D is necessary. As the authors suggest, the current trend towards diets with animal-derived foods being at least partially replaced by plant-based foods will further increase the risk of sub-optimal status of vitamin B12 and D (and other nutrients) in women of childbearing age. This needs to be considered when such dietary transition is contemplated.”

‘Maternal B-vitamin and vitamin D status before, during, and after pregnancy and the influence of supplementation preconception and during pregnancy: Prespecified secondary analysis of the NiPPeR double blind randomized controlled trial’ by Keith M. Godfrey et al. was published in PLOS Medicine at 19:00 UK time on Tuesday 5 December 2023.

DOI: 10.1371/journal.pmed.1004260

Declared interests

Dr Duane Mellor: No COI’s.

Prof Ian Givens: I have no conflicts to report.