Vitamin B₁₂status in women of childbearing age in the UK and its relationship with national nutrient intake guidelines: results from two National Diet and Nutrition Surveys

Abstract

ObjectiveTo assess serum B12, folate and the associated homocysteine (Hcy) levels among women of childbearing age in the UK and examine their association with dietary intake in relation to the UK Recommended Nutrient Intakes (RNIs) for B12 and folate.DesignCross-sectional study.SettingData from two publicly available National Diet and Nutrition Surveys (NDNS 2000/2001 and 2008/2012) were used. These were population-based surveys of randomly selected samples of adults which were carried out in their households.ParticipantsWomen of childbearing age (aged 19–39 years), representative of the UK population. Those who were pregnant or breastfeeding were excluded.Outcome measuresThe associations between micronutrient intakes and blood levels of B12, folate and Hcy were assessed by correlation and stepwise linear regression. B12 intake was divided into quintiles and plotted against blood B12 and Hcy concentrations to determine the threshold of any associations.Results299 women from the first NDNS cohort had complete intake and biomarker data. The prevalence of serum vitamin B12 (≤150 pmol/L) and serum folate (≤10 nmol/L) deficiency and hyperhomocysteinemia (≥12 µmol/L) was 12.4%, 6.4% and 21.2%, respectively, despite seemingly adequate B12 intakes (median 3.8 μg/day, 96% consumed more than the UK RNI of 1.5 μg/day). B12 concentrations increased across all quintiles of intake with serum levels in quintiles 4 and 5 (median intake 4.9 and 7.1 μg/day, respectively) significantly higher than quintile 1. However, Hcy concentrations levelled off between quintiles 4 and 5. Comparison of micronutrient intake between the two surveys found that folate intake has reduced in the more recent cohort.ConclusionsThe UK RNI for B12 intake should be increased for women of childbearing age with intakes of around 5–7 μg/day likely to be associated with stable biomarker levels. B12 levels should also be measured in women preconceptionally or in early pregnancy given the high rates of deficiency.

Mosaic chromosome Y loss is associated with alterations in blood cell counts in UK Biobank men

“…And the most common causes for macrocytic anemia were vitamin B12 and folate deficiency 70 . A report in 2016 on National Diet and Nutrition Surveys found that 12.4% and 6.4% women in childbearing age were deficient in serum vitamin B12 and folate despite 96% consumption of adequate B12 in UK 71 suggesting that the current recommended intake of vitamin B12 and folate might require adjustment to accommodate difference in life style or genetic background which may influence bioavailability. The intake and deficiency of vitamin B12 and folate among men was under-studied.…”

Vitamin B12 Status among Pregnant Women in the UK and Its Association with Obesity and Gestational Diabetes

“…Low B12 can have an impact on fetal birthweight by influencing placental development [17], although evidence for association with low birthweight (LBW) is equivocal [18,19,20]. At the other end of the spectrum, maternal obesity and insulin resistance are well-known to be associated with higher fetal birthweight [21,22].…”

Effects of a 3-month dietary intervention with a lacto-ovo-vegetarian diet on vitamin B12 levels in a group of omnivores: results from the CARDIVEG (Cardiovascular Prevention with Vegetarian Diet) study

“…In our dietary intervention study, despite baseline dietary intake of vitamin B 12 similar to that observed in the general adult population (21,22) , the exclusion of meat and fish during the VD period resulted in a reduction in vitamin B 12 intake and a consequent decrease of circulating levels. Although clinically irrelevant and within the normal range, probably due to the limited duration of the intervention, this reduction confirms that switching from an omnivorous to a VD may result in a reduction in the levels of circulating vitamin B 12 .…”