A decade after Canada adopted a groundbreaking policy of fortifying flour-based products to prevent birth defects, the levels of folic acid purported to be in foods remain wildly inaccurate, new research reveals.
The study, published in the Canadian Journal of Public Health, shows that pasta, breads and cereals can contain anywhere between 90 per cent and 377 per cent of folic acid claimed on the product label.
"People expect that what's on the label is accurate, but it's not," said Deborah O'Connor, director of clinical of dietetics at the Hospital for Sick Children and principal author of the research.
She said that the high levels of folic acid found in food are "probably not causing people any health problems" and they may even be beneficial but insisted that there is an important principle at stake.
"When we add things to food, we should monitor them. Otherwise, you can't make good public-health decisions," Dr. O'Connor said.
In 1998, the federal government adopted a policy of mandatory fortification of white flour, enriched pasta and cornmeal, a program that has been copied in a number of other countries.
Since then, the incidence of neural tube defects such as spina bifida has dropped by more than half. Fortification (as well as supplementation with prenatal multivitamins) has also led to sharp reductions in heart defects and a form of childhood cancer called neuroblastoma.
There is now a move afoot to double the levels of folic acid added to foods, in a bid to further reduce these birth defects.
But before doing so, Dr. O'Connor said, it is essential to know how much folic acid is actually added to food now.
Her team is the first to conduct such an analysis in Canada. The Sick Kids researchers tested the 92 most commonly purchased folic-acid-fortified foods including breads, buns, cookies, crackers, cooked pasta, packaged desserts and ready-to-eat cereals.
On average, products contained about 50 per cent more folic acid than stated on product labels.
While the benefits of folic acid are many, there are some risks associated with ingesting too much of the vitamin. For example, excess folic acid can mask vitamin B12 deficiency, a common cause of anemia in the elderly, and it can interfere with drugs used to treat rheumatoid arthritis, psoriasis and malaria.
Dr. O'Connor said it is unlikely a person would consume too much folic acid from fortified foods alone, but many people also take supplements to bolster their levels.
It is recommended that all women of childbearing age take a daily prenatal multivitamin which contains between 0.4 and 1 mg. of folic acid.
That is because almost half of pregnancies are unplanned, and folic acid is essential in the first month after conception – when many women are not yet aware they are pregnant – as the neural tube (which later becomes the spinal cord) forms in the embryo.
Folate, or vitamin B9, is found in leafy green vegetables such as spinach, in legumes such as chickpeas and fruits such as oranges. The synthetic version, folic acid, is added to commercially prepared grain products and sold in the form of supplements.