Today’s study in the Journal of the American Medical Association followed up a group of Norwegian people with cardiovascular disease, given either folic acid (800mcg) with B12 and some with B6 versus placebo over 6 years. Norway hasn’t fortified food so this is a good population to study. They found that 10% of those receiving folic acid were diagnosed with cancer, compared to 8.4%. That is a relative increased risk of 24% although an absolute increased risk of 1.6%. The relative risk of dying from cancer was 38% higher in those taking folic acid and the absolute increase in risk was 1.1%. These are not great increases but they were statistically significant.
However, contrary to logic, there was no statistically significant increase in risk for colo-rectal cancer, as was predicted. Most of the increased cancer risk was due to deaths from lung cancer, primarily among smokers and those with a variation in the gene that makes a key methylation enzyme (MTHFR -677T). Roughly 10% of the population have this gene variation and many smoke so this study, the only one so far in a country that hasn't fortified food with folic acid, does suggest that fortification is going to lead to more cancer deaths. However, if you don't smoke and don't have this gene variation the concern of these findings becomes less.
Folic acid in supplements, and in fortification, is slightly different to what is found in food, which is called folate (tetrahydrofolate) and has an additional methyl group. There is some conjecture as to whether having too much circulating folic acid, as opposed to folate may be part of the problem.
Folic acid has many benefits which I’ve discussed in my article ‘Why folic acid fortification may not be good news’ in the January newsletter last year. My advice is not to supplement too much – above 400mcg – unless you know your homocysteine level which can be tested on a home-test kit. The reason for saying this is that, by all accounts, having a high homocysteine level is bad news as far as health and cancer risk is concerned. A high homocysteine level is a reliable indicator that you are not receiving either enough B6, B12 or folic acid. By increasing these and lowering your homocysteine level you are likely to reduce risk.
Also, bear in mind that this is a study of people with cardiovascular disease and, since most of the increased risk relates to lung cancer, most of those affected are also smokers. So, if you do not smoke and don’t have cardiovascular disease this small potential increase in risk may not apply to you. Also, if you are following my overall advice the chances are your immune system is stronger than that of a smoker with cardiovascular disease, and may be more able to eliminate cancer cells.
However, in principle, this study provides yet more reason not to tackle spina bifida risk with mass supplementation of folic acid via food fortification before we know more. We are all different and it is best to assess your needs either with my on-line 100% Health Programme or by seeing a nutritional therapistand, at least, by knowing your homocysteine level. It certainly adds to concerns about taking high dose folic acid if you have cancer or a precancerous condition.