South Asian Ethnicity Is Related to the Highest Risk of Vitamin B12 Deficiency in Pregnant Canadian Women

Abstract

Vitamin B12 (B12) adequacy during pregnancy is crucial for maternal health and optimal fetal development; however, suboptimal B12 status has been reported in pregnant Canadian women. Methylmalonic acid (MMA) is a sensitive indicator of B12 status. Since few studies have measured MMA during pregnancy in Canadian women, the objective of this study was to evaluate B12 status in pregnant women living in Metro Vancouver, using both plasma total B12 and MMA. We recruited a convenience sample of 320 pregnant women between 20 and 35 gestational weeks from local healthcare facilities. Plasma total B12 concentrations indicative of deficiency (<148 pmol/L) and suboptimal B12 status (148–220 pmol/L) were found in 18% and 33% of the women, respectively. Normal plasma MMA concentration (<210 nmol/L) was observed in 82% of all women. Gestational age was a strong predictor of plasma total B12 and MMA concentration, and South Asian ethnicity of B-12 deficiency and MMA concentrations. Overall, there was a high discrepancy between the prevalence of B12 inadequacy depending on the biomarker used. Independently, however, South Asian women were at particular risk for B12 deficiency, likely due to lower animal source food intake. Further study of this vulnerable group and performance testing of B12 biomarkers is warranted.

The Effects of Vegetarian and Vegan Diet during Pregnancy on the Health of Mothers and Offspring

“…Pre-pregnancy BMI was the strongest independent predictor of plasma total B12 concentration. One limitation of this data was the absence of a dietary assessment to quantify B12 intake, as this specific population promoted vegetarianism [69]. A study conducted in small sample of pregnant Indian women showed that hyperhomocystinemia leads to global DNA hypermethylation in vegetarian population due to low dietary intake of vitamin B-12 during pregnancy and that this could predispose to cardiovascular risk and obesity [70].…”

Pregnant women of South Asian ethnicity in Canada have substantially lower vitamin B12status compared with pregnant women of European ethnicity

“…The prevalence of B 12 deficiency, defined as serum total B 12 concentration <148 pmol/l, among reproductive-aged and pregnant women in Canada (25)(26)(27)(28)(29)(30) and the UK (31) was reported to range between 5 and 40 %. A recent cross-sectional study in pregnant women (20-35 weeks of gestation) residing in Vancouver, Canada, in which 18 % of the total sample had a total B 12 concentration <148 pmol/l, revealed a markedly higher prevalence among women whose self-identified ethnicity was South Asian (61•5 % (n 16/26)) compared with European (16 % (n 24/150)) (30) . Taken together, B 12 status Abbreviations: B 12 , vitamin B 12 ; holoTC, holotranscobalamin; MCA, 2-methylcitric acid; MMA, methylmalonic acid; tHcy, homocysteine.…”

“…Logistic challenges and cultural barriers have been identified limiting health research in South Asians ( 24 ) . The prevalence of B 12 deficiency, defined as serum total B 12 concentration<148 pmol/l, among reproductive-aged and pregnant women in Canada ( 25 – 30 ) and the UK ( 31 ) was reported to range between 5 and 40 %. A recent cross-sectional study in pregnant women (20–35 weeks of gestation) residing in Vancouver, Canada, in which 18 % of the total sample had a total B 12 concentration<148 pmol/l, revealed a markedly higher prevalence among women whose self-identified ethnicity was South Asian (61·5 % ( n 16/26)) compared with European (16 % ( n 24/150)) ( 30 ) .…”

Approaches to improving micronutrient status assessment at the population level

“…In late pregnancy, i.e. in second or third trimester, pregnant women of South Asian ethnicity had the highest risk of B 12 deficiency compared with women of other ethnicities ( 57 ) . Underlying causes may be differences in dietary B 12 intake and supplement use related to cultural habits and traditions, potentially higher prevalence of vegetarianism, and/or higher prevalence of genetic variants related to lower serum total B 12 concentrations ( 58 ) .…”