Further evidence of the harmful effects of folate deficiency during pregnancy are revealed as scientists at the Institute of Cancer Research report a possible link between levels of folic acid available to the baby in the womb and leukaemia in children.
Women are already advised to take supplements of folic acid while trying to conceive and throughout pregnancy to help avoid the risk to the foetus of brain damage and spina bifida. Deficiency of folic acid is known to lead to breaks in DNA, and low dietary intake of folic acid has been associated with increased risk of some cancers in adults, including colon and breast cancer.
This latest research, part of the UK Childhood Cancer Study funded by the Leukaemia Research Fund and led by Professor Mel Greaves at The Institute of Cancer Research, suggests that children exposed to higher levels of folic acid in the womb have a significantly lower risk of developing leukaemia.
The scientists examined British children diagnosed with leukaemia from 1992 until 1998 and compared them with healthy children.
Commenting on the findings Professor Greaves said: "We know that many cases of childhood cancer are initiated before birth by chromosome damage, so we wanted to find out if folic acid levels in cells in the developing foetus might influence risk. The active levels of folate in the cell are determined both by dietary intake, via the pregnant mother, and by genetic variations that determine how individuals process folate."
One of the key enzymes central to the processing of folic acid, breaking it down and reducing its levels, is called MTHFR. Some individuals inherit a variant MTHFR gene - c677T, which renders MTHFR inactive and so preserves higher levels of folic acid in cells for maintaining intact DNA. Children who had inherited the inactive enzyme were found to have a significantly lower risk of leukaemia, which is presumed to be due to a reduced likelihood of chromosome damage in the womb.
A recent epidemiological study carried out at the Cancer Foundation of Western Australia endorses this explanation. The scientists found that use of folic acid during pregnancy almost halved the risk to children of developing leukaemia.
Dr David Grant, Leukaemia Research Fund scientific director, said: "About one in 2,000 children will be diagnosed with leukaemia, most between two and four years of age. Professor Greaves' work at the Institute of Cancer Research is showing that some of these children are almost certainly born with defective blood cells which go on to become leukaemic cells.
"The realisation that damage to the DNA in these cells can be reduced with folate supplements in pregnancy is extremely exciting and could help to reduce the number of cases of this terrible disease in children. This is a very interesting lead and we look forward to the results of further studies."
Professor Peter Rigby, chief executive of the Institute of Cancer Research, added: "This research has given us a clearer understanding of the role of folic acid. We hope that further research will shed more light on this in relation to childhood cancer, and provide the evidence that is needed for a more radical health policy, and longer term to a reduction in childhood cancers."