By Lucy Jones RD
Recent headlines have warned women that vitamin supplements in pregnancy are a “pointless waste of money” and have “no evidence they boost health,” seemingly discouraging micronutrient supplementation at this crucial time.
These were based on a review in the Journal Drug and Therapeutics Bulletin on vitamin supplementation in pregnancy1.
The study itself acknowledged that “ensuring a woman is well-nourished, both before and during pregnancy, is crucial for the health of the woman and that of the unborn child1.” They also acknowledge that “maternal deficiency in key nutrients has been linked to pre-eclampsia, restricted fetal growth, neural tube defects, skeletal deformity and low birth weight1.” Their argument against supplements was based on their report that “much of the evidence for vitamin supplementation in pregnancy comes from studies carried out in low-income countries, where women are more likely to be undernourished or malnourished than within the UK population1.” They concluded that “for most women who are planning to become pregnant or who are pregnant, complex multivitamin and mineral preparations promoted for use during pregnancy are unlikely to be needed and are an unnecessary expense.1”
It is important to note that the authors aren’t named and therefore we have no idea of their qualifications, links to different companies or indeed who paid for the article to be written. The “study” is actually a narrative or opinion based review, rather than a new piece of research. Since there was no detail on their reviewing methods, we don't know if the researchers assessed all of the available evidence on the supplements or whether they simply cherry picked ones that fit in with their recommendations. This means that the entire report needs to be interpreted with a level of caution. Unfortunately, none of the media reports picked up on this, reporting the study as though it was conclusive fact.
Micronutrient needs in pregnancy certainly warrant headlines – they are higher than usual and inadequate intakes can have far reaching implications. Whilst the UK government at present only recommends folic acid and vitamin D supplements in pregnancy2, this does not mean that other nutrients do not have an important role to play. For example, omega-3 fatty acids contribute to babies’ brain and eye development3 and to the maintenance of normal brain function4, iron supports blood formation and the immune system5, choline helps to prevent neural tube defects6 whilst iodine contributes to babies’ brain development7. A large UK study has shown that two thirds of pregnant women were iodine deficient with low levels in pregnancy reducing their children’s IQ and reading ability aged 8-98.
It is well known that uptake of supplements, even folic acid supplements, is poor in pregnancy, particularly among those from lower income families1. The authors acknowledged this and suggested that focus should turn to this, rather than multivitamin based supplements. A recent survey illustrated that less than a third (30.3%) of new mums were aware of the role that vitamin D has in pregnancy and breastfeeding, nor that supplements are recommended for this nutrient, let alone the lesser-known nutrients9. Unfortunately, the headlines that followed are only likely to perpetuate this low uptake with many more people deciding against all forms of supplements during pregnancy. But does this matter if we get everything we need from our food?
The authors state that the research demonstrating benefit of supplements is mostly from developing countries with higher rates of malnutrition than the UK. However, the National Diet and Nutrition Survey tells a different tale.
The latest findings from a national diet survey, the NDNS, show worryingly low intakes of a variety of nutrients in young women. Very low intakes (below the Lower Reference Nutrient Intake - the LRNI only meets 2.5% of the populations’ need) were found in a significant number of teenage girls for vitamin A, riboflavin and folate. Young women also had very low intake of riboflavin10.
Severe vitamin D deficiencies were found in no less than a quarter of teenage girls, whilst average iron intakes were inadequate for both women and teenage girls with 23% of women and 46% of teenage girls and young women having iron intakes below the LRNI10. Average intakes of calcium, zinc and iodine were also inadequate in teenage girls with about a fifth of them falling below the LRNI10.
Additional minerals consumed at inadequate levels included potassium, magnesium and selenium. In terms of food groups, less than a third of adults met the “five-a-day” recommendation for fruit and vegetables and the average intake of oily fish was under half a portion a week, completely inadequate for healthy omega-3 status10.
It’s important to note that in general, supplement takers had higher intakes of vitamins and minerals from food sources than those who did not take supplements but the contribution from supplements had little effect on the proportion of participants below the LRNI10, indicating that the people who really needed the weren’t taking them, much like the situation in pregnancy.
So this new review stated that there is no evidence to suggest a need for vitamin supplementation in well-nourished women. But according to the National Diet and Nutrition Survey, significant proportions of women are not well nourished and would therefore well benefit from supplements.
What should we learn from this?
Always check the story behind a headline – in this case, the “study” was actually a narrative review or opinion piece, rather than a well carried out piece of new research.
Supplements have an important role to play both in bridging the existing gaps between intakes and requirements for everyday life and also for meeting the higher needs of nutrients required in pregnancy, without the provision of excessive calories from additional food.
I doubt anyone would argue that eating a good, balanced diet during pregnancy, along with folic acid and vitamin D supplements ensures the best possible health for the mother and unborn child, however we need to acknowledge the role of a variety of nutrients at this special time. Doctors need to be aware of the crucial time that the first 1000 days of life is for nutrition for cementing whole life health risks and feel confident to advise women to supplement where dietary shortfalls may exist in addition to improving the diet.