The research focused on 11 patients, all of whom had recurrent pre-cancerous growths (adenomatous polyps) in their bowel.
Six of the patients supplemented their diet with 2 mg folic acid tablets every day for 3 months. The rest were given a dummy or placebo tablet.
To identify if the folate supplements had any noticeable effect, biopsy tissue was taken from inside the rectum, before the trial began, and then at intervals of 4, 12, and 18 weeks.
The researchers were particularly interested in the effect on the crypts - cavities or pits along the lining of the bowel.
Each of these crypts was divided into 5 sections, running from the base to the surface.
The numbers of actively dividing cells, which have the potential to form polyps and become cancerous, were counted in each section.
| Folate reduced number of proliferating cells in the crypts of the bowel lining.
At the start of the trial, there was no difference between the 2 groups.
However, over the course of the trial, the number of proliferating cells fell significantly in the crypts of those given the folate supplement.
After supplementation had been discontinued for 6 weeks, the cellular activity started to return to the levels seen before the trial started.
The researchers note that the doses of folic acid given were considerably higher than would be expected in the average daily diet.
Also, in people who are B12 deficient, who have advanced cancer, or who are taking drugs for epilepsy, folate may be harmful.
However, they say their findings suggest that folate supplements may enhance the repair of cellular DNA after it has been damaged, so reducing the risk of cancer in susceptible people.