Expert calls for the review of B-vitamin guidelines during pregnancy
This was the key message from a presentation given by professor Kristina Pentieva from Ulster University, during the Nutrition Society’s Summer Conference earlier this month.
She drew attention to the guidelines published by the Department of Health and the European Food Safety Authority (EFSA) for B-vitamin intakes during pregnancy, which she said were outdated with increments based on little evidence.
She pointed out that recent studies conducted by her team have noted that supplementation with folic acid and riboflavin throughout pregnancy resulted in significantly improved cognitive performance in the children, when compared to control groups.
Physiological changes during pregnancy
“Maternal nutrition is incredibly important, not only for the successful outcome of pregnancy, but also for the future health of the offspring and mother,” Pentieva stressed.
She explained how many different physiological and metabolic changes take place during pregnancy, which are mostly driven by increases in oestrogen and progesterone resulting in increases in plasma virome and total body water.
She emphasised that a resultant drop in albumin causes many B-vitamins to be in their free-from and thus, are more prone to destruction. Furthermore, increases in the gastric acid pH during pregnancy reduces the vitamin’s bioavailability.
Yet, there are heightened requirements for B-vitamins during pregnancy due to an increase in red blood cell count, which further reduces maternal levels.
She emphasised: “With the progression of pregnancy there is the considerable reduction of B-vitamins in the circulation. For example, folate decreases by around 50%.”
Dietary interventions
Despite this well recognised drop in B-vitamin levels during pregnancy, Pentieva said that there is still a lack of specific criteria for the assessment of its status during pregnancy.
She explained: “The usual response is ‘Oh, there is a physiological fall in B-vitamins during pregnancy, so it is pretty normal’, but how much is normal? And when is there a deficiency?”
She highlighted that current recommendations for pregnant women do not include additional increments of intake for B12 or B6.
“The most important point as that the recommendations are based on very little research. There is more on folate, but it is very limited for the other B-vitamins.
“More research is needed into this area to ensure the successful outcome of pregnancy without compromising the health of the mother,” she urged.
B-vitamin supplementation
She describes the well-documented evidence highlighting the effectiveness of folate supplementation before pregnancy to prevent against neural tube defects in infants.
Yet, she questions whether folate supplementation should extend throughout the duration of pregnancy, with observational studies suggesting it may improve cognitive scores in children.
She explained a subsequent RCT conducted by her team, investigating the effects of 400 μg/d of folic acid or a placebo from the 14th gestational week until the end of pregnancy in 119 mothers. Cognitive performance of the children was measured at 3 years and 7 years of age.
“For the cognitive domain, the folic acid supplemented children scored higher in comparison to the children from the placebo group,” she stressed, adding that a similar outcome was observed for language scores.
She added that a follow up study measuring the brain activities in the children, using magnetoncephalographic (MEG) brain imaging, concluded that the continued folic acid supplementation resulted in more efficient semantic processing of language.
“Obviously there is a positive impact of folic acid supplementation on cognitive performance,” regarding the addition of the objective evidence to support previous conclusions.
In addition, she added that her on-going, unpublished study has found that riboflavin supplementation during pregnancy may reduce the risk of hypertension and anaemia; conditions she said can lead to adverse, and event fatal, outcomes in pregnancy.
The science
She explained that folate and vitamin B12 are both involved in DNA synthesis, genomic stability, cell division and tissue growth, and different methylation reactions.
“Riboflavin is involved mainly in energy generating interactions, so oxidation-reduction interactions, in intermediatory metabolism, glutathione reductase cycle which is the most powerful antioxidant in the body,” she said.
She continued to describe the importance of all B-vitamins within one-carbon metabolism; an essential process for the synthesis of DNA, amino acids, and phospholipids. Therefore, she stresses that these vitamins, particularly B6, B12 and riboflavin, should be provided in balanced quantities to ensure these vital pathways function correctly.
