The UK's Food Standards Agency recently decided not to recommend the fortification of flour with folic acid, citing the fact that there was insufficient evidence of the potentially adverse effects of such a move.
The move was broadly condemned by scientists, who stressed the mounting evidence of the benefits of folic acid, especially on preventing neural tube defects such as spina bifida.
It is perhaps ironic, therefore, that the latest evidence of the benefits of the B vitamin come from researchers in the UK itself. A team of researchers from the Royal Victoria Hospital in Belfast, Northern Ireland, led by Dr K Khosraviani, have discovered that folic acid could help reduce the risk of colorectal cancer.
Writing in the journal Gut, Dr Khosraviani's team said they had carried out a comparative trial over an 18-week period, focusing on 11 patients with recurrent adenomatous (benign) tumours in the colon.
The researchers took rectal biopsies at the start of the trial at 10 cm from the anal verge prior to folate supplementation, and were then repeated after four, 12, and 18 weeks. The team then calculated the number of actively dividing cells - the ones which have the potential to form polyps and become malignant.
Dr Khosraviani's team found that while there was no difference between the six patients supplemented daily with 2 mg of folic acid and the five given a placebo at the start of the trial, the number of proliferating cells fell considerably in the supplemented group. Six weeks after the end of supplementation, the cellular activity in the treatment group started to return to the levels seen before the trial started.
The researchers suggest that folate supplements may regulate colonic mucosa cell proliferation in patients with recurrent adenomatous polyps, a sub-group at high risk of colon cancer. They added that the doses of folic acid given to the patients in their study were far higher than those likely to be obtained through diet alone, and that such high doses could have an adverse effect on people who are vitamin B12 deficient, have advanced cancer or who are on medication for epilepsy.