TORONTO — Most Canadians have adequate blood levels of folic acid, and in fact some of us may be getting too much of the B vitamin through diet and supplements, researchers suggest.
In a study based on a sample of more than 5,200 Canadians aged six to 79, researchers found that less than one per cent of the population is deficient in folic acid, while 40 per cent have high folate concentrations.
But the study, published Monday in the Canadian Medical Association Journal, also discovered that 22 per cent of women of child-bearing age had folate concentrations below what’s considered optimal for preventing neural tube defects as spina bifida in newborns.
Folic acid, which has been added to flour and other grain products since 1998, is also believed to play a role in preventing congenital heart disease and cleft palates in children.
“Now that we have this data, we know that very few Canadians are deficient; in fact, now we’re having this shift towards high levels,” said lead author Cynthia Colapinto, a PhD candidate in population health at Children’s Hospital of Eastern Ontario Research Institute, which conducted the study with researchers at Toronto’s Hospital for Sick Children.
“It causes some questions (about) our policies related to fortifying grain products with folic acid, supplement recommendations, the amount contained in supplements and that type of thing,” she said Monday from Ottawa. “So we want to understand who this population is that’s above . . . and what kind of changes possibly need to be made.”
To decrease the incidence of birth defects, some medical groups have suggested that government should consider mandating a doubling of folic-acid fortification in staple foods like bread and cereal.
However, the authors said ramping up folic-acid fortification in food with the hope of increasing levels in women of child-bearing age would also expose the rest of the population to amounts they may not need and that could be dangerous in the long term.
That’s because there’s been speculation that excessive intake of folic acid may be linked to the development of colorectal cancer and possibly other diseases.
“The reason we have fortification of foods is to specifically target these women,” said Colapinto. “They’re the ones who we say need a folic acid supplement and should be eating folate-rich foods.”
In addition to following Canada’s Food Guide, women who might get pregnant or plan to get pregnant are advised to take a 400-mcg supplement of folic acid daily in order to minimize the risk of birth defects in their babies.
“When it comes to neural tube defects, we have very good evidence that fortification with folic acid — so taking more folic acid and not being folic-acid deficient — has been a very successful strategy. We’ve had a 46 per cent decrease in neural tube defects since fortification was implemented in 1998.”
But she said the new data suggest that increasing fortification in foods eaten by the entire population may not be the best idea.
“There is very little folate deficiency in Canada, so we are getting enough folate. The general population — so men, children — don’t necessarily need extra folic acid outside of their diet, so if they are taking supplements, they should be aware how much they are taking.”
However, knowing how much one should take is problematic, Colapinto conceded, as no recommended optimal amounts have been decided beyond that for women of child-bearing age.
The new data, collected between March 2007 and February 2009, should help health organizations and government policy makers refine their recommendations related to folic acid intake, she said.
Dr. Gideon Koren, head of the Motherisk program at Toronto’s Hospital for Sick Children, was not involved in the study. But he said its finding that more than one in five Canadian women of child-bearing age is deficient in folic acid underscores the need to target this group specifically.