Arbor Clinical Nutrition Updates

Brief Report

Can folate supplements be dangerous? - part 2

CJ. Piyathilake et al. Mandatory fortification with folic acid in the United States appears to have adverse effects on histone methylation in women with pre-cancer but not in women free of pre-cancer. Int J Women Health. 2010 Aug 9;1:131–7.

K. Wu et al. A randomized trial on folic acid supplementation and risk of recurrent colorectal adenoma. Am J Clin Nutr. 2009 Dec;90(6):1623–31.

R. Clarke et al. Effects of lowering homocysteine levels with B vitamins on cardiovascular disease, cancer, and cause-specific mortality: Meta-analysis of 8 randomized trials involving 37 485 individuals. Arch Intern Med. 2010 Oct 11;170(18):1622–31.

In a nutshell

Whilst adequate folate is protective against cancer, there are theoretical grounds and some clinical evidence to suggest that, in people with existing pre-cancerous or cancer cells, folate supplements could stimulate their growth.

However, more studies have failed to show this than have reported it, and so the hypothesis remains neither confirmed nor refuted. Until this matter is resolved, some caution is appropriate, particularly in those who may already have early stage tumour.