Science stacks up for B vitamins and pregnancy
may have detrimental knock-on effects to the offspring, suggests a
new Dutch that reports higher risk of heart problems.
A combination of low vitamin B12 levels and certain genotypes for the methionine synthase reductase (MTRR) and transcobalamin II (TC) genes were found to increase the risk of CHD by about 35 and 100 per cent, respectively, report the researchers in the journal Molecular Genetics and Metabolism. "Therefore, it might be favorable to advise women to use a diet rich in vitamin B12 and eventually a vitamin B12 supplement in addition to a folic acid supplement in the periconception period to achieve an optimal vitamin B12 status," wrote Anna Verkleij-Hagoort from Erasmus MC, University Medical Center in Rotterdam. The importance of B vitamins, particularly folate, in foetal development is well established. The new study expands our understanding of the potential of pre-conception diets to influence the health of offspring. The research builds on reports from epidemiological studies that increased levels of the amino acid homocysteine may lead to an increased risk of cardiovascular disease (CVD). Moreover, high levels of the amino acids in mothers has been associated with congenital heart defects (CHDs) in the offspring, state the authors in background information in the article. Verkleij-Hagoort and co-workers studied 230 children with a CHD and 251 health control children and their parents. Current and peri-conception maternal dietary and supplement intakes were assessed using a validated semiquantitative food frequency questionnaire (FFQ). Blood samples were taken in order to determine the MTRR A66G and TC C776G genotypes in the families. Consideration of the MTRR and TC genotypes alone was found to have no effect on CHD risk. However, low blood levels of vitamin B12 in the mothers and in combination the maternal or child's MTRR 66 GG genotype were found to increase the risk be 40 and 30 per cent, respectively. Furthermore, a TC 776 GG genotype in mothers and children and low maternal vitamin B12 levels increased the risks of CHD by 120 and 90 per cent, respectively, wrote the authors. "In conclusion, MTRR 66 GG and TC 776 GG genotypes in mothers and children may contribute to the risk of CHDs, particularly when the maternal vitamin B12 status is low," wrote Verkleij-Hagoort. "Future research may focus on other polymorphisms in the MTRR and TC genes, their functional and biochemical effects and the implications of lifestyle factors in order to gain insight into the role of vitamin B12 in the pathogenesis of CHDs," concluded the researchers. Currently, supplementation with folate and folic acid - the synthetic, bioavailable form of folate - is recommended to all women of child-bearing age since most neural tube defects (NTDs), including spina bifida and anencephaly, occur within the first 22 to 28 days of pregnancy, when the mother-to-be is not aware she is even pregnant. Folic acid supplements after this time are too late to prevent neural tube defects and therefore fail to benefit women with unplanned pregnancies - more than half of all pregnancies in the US. This connection between folate deficiency in early pregnancy and an increased risk of NTDs led to the 1998 introduction of public health measures in the US and Canada, where all grain products are fortified with folic acid. While preliminary evidence indicates that the measure is having an effect with a reported 15 to 50 per cent reduction in NTD incidence, parallel measures in European countries, including the UK and Ireland, are still on the table. Earlier this year an epidemiological study report that high levels of vitamin B6 prior to falling pregnant may boost conception rates and reduce the odds of losing the baby during early pregnancy (American Journal of Epidemiology, Vol. 166, pp 304-312). Additionally, a recent study with sheep, published in the prestigious journal Proceedings of the National Academy of Sciences, indicated that mothers with low B vitamin levels before conceiving tend to have fatter male offspring at greater risk of high blood pressure. The findings were deemed to be important for species with two legs, since the pre- and post-natal development of sheep is approximately the same as humans. Source: Molecular Genetics and Metabolism (Elsevier) Published online ahead of print 15 January 2008, doi:10.1016/j.ymgme.2007.12.002 "Genetic and lifestyle factors related to the periconception vitamin B12 status and congenital heart defects: A Dutch case-control study" Authors: A.C. Verkleij-Hagoort, L.M.J.W. van Driel, J. Lindemans, A. Isaacs, E.A.P. Steegers, W.A. Helbing, A.G. Uitterlinden and R.P.M. Steegers-Theunissen