Wednesday, December 15, 2004

Folate and breast cancer

'Cancer danger of folic acid', reports the UK Daily Express, following a study published in the British Medical Journal (BMJ). Between 1966 and 1967, about 3,000 pregnant women from the Aberdeen area were given low or high doses of folate, or a placebo. (Folic acid is the form in which folate is taken as a supplement.) The new study re-examined their medical records in 2002 to find out what had happened to them. In all, 210 had died, 31 of them from breast cancer. The rate of breast cancer among those taking a placebo (that is, not taking folate) was around half that of women on the highest dose.

Women, both in pregnancy and prior to pregnancy, are strongly urged to take folate to avoid birth defects like spina bifida. So headlines like the one in the Express can be pretty alarming. However, this study goes nowhere near proving a link between folic acid supplements and cancer.

For one thing, the fact that less than 10 per cent of the women concerned had died almost 40 years after taking part in the study suggests that any effect is likely to be weak. This view is strengthened by how few died from breast cancer - about one per cent. Moreover, this work contradicts other studies which suggest no effect, or even a protective effect, from folate in relation to cancer. In a commentary in the BMJ published with the study, Godfrey Oakley and Jack Mandel argued that 'the most likely explanation for the reported association is chance', noting that the results were not statistically significant.

The only purpose for publishing a weak study like this would be as a general note to other researchers. It certainly doesn't warrant the attention of the general public. The fact that it was given considerable coverage indicates that in a society obsessed with vulnerability, pregnancy is the biggest concern of all. Women are advised to avoid a whole host of foods and activities on the basis that any risk to the gestating fetus must be avoided at all costs - an utterly bizarre state of affairs as infant mortality is at an all-time low in the West.

This obsession with vulnerability at times becomes contradictory, as plainly illustrated here. If this study were correct, where would that leave us? Take folate, avoid birth defects. Don't take folate, avoid breast cancer. Damned if you, damned if you don't. Fortunately, the risks either way are, at worst, small - but the combination of inadequate research and newspaper scare stories does nobody any favours.

'Cancer danger of folic acid', Daily Express, 10 December 2004

Taking folate in pregnancy and risk of maternal breast cancer, British Medical Journal, 14 December 2004

0 Comments:

Post a Comment

<< Home