Folate supplement-cancer link: study raises new concerns
27 November 2009
More evidence has emerged linking folic acid supplementation with an increased risk of cancer.
A combined analysis of 2 Norwegian studies has found people with ischaemic heart disease who received 0.8 mg per day of folic acid plus 0.4 mg per day of vitamin B12 had an 18 per cent increased risk of death from any cause compared with controls (JAMA 2009; 302: 2119-26).
Deaths were primarily due to an increase in lung cancer, the authors said.
However, people receiving folic acid and vitamin B12 had a 21 per cent increased risk of being diagnosed with any form of cancer. The 2 randomised trials included 6837 participants.
In Australia, expert opinion is divided on the risk-benefit analysis of folate supplementation, with some media reports down-playing the findings.
An editorial accompanying the paper said the dosage in the trials was above average supplementation in most countries. However, Dr Mark Lawrence of the school of exercise and nutrition sciences at Deakin University said the findings added to a developing trend linking folate supplementation with cancer incidence.
“This study, it must be remembered, is in patients with ischaemic heart disease, so it’s a defined group, but it’s a large sample and it’s randomised, and collected in a non-contaminated population – one that hasn’t been exposed to folate fortification.”
Professor Lawrence said the editorial was being “a bit naïve about dosage in accepting at face value what the regulations say. What’s been shown in the US is that many manufacturers include more that the minimum dose in their products, they over-fortify.”
Australia began fortifying bread-making flour with folate in September 2009.
Creswell Eastman, clinical professor of medicine at the University of Sydney, said while the results might have little or no relevance to mandatory fortification, they were important given the number of people taking folate supplements.
“It is of concern because it is now a common practice for middle-aged men and women to take high-dose folate supplements in the belief that it is protective against coronary heart disease,” said Professor Eastman, a member of an expert panel which recommended mandatory folate and iodine fortification in 2005.
“Are we trading off one disease to get another?”
Last Reviewed: 27 November 2009
- 1. Ebbing M, Bonaa KH, Nygard O, et al. Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12. JAMA 2009; 302: 2119-2126
