I was in a café the other day when I heard a woman say she’d been diagnosed as B12-deficient.
“Really?” I said. “Me, too!”
I’m a meat eater, but it’s often vegans who are afflicted since B12 is only found in animal products. But on further exploration I learned two things: first, there’s disagreement over who’s deficient and what that means. And second, you can’t talk about B12 without dragging in folic acid, since the vitamin is needed for folate to metabolize.
Except now, reports are linking too much folic acid and B12 to cancer. This is a bitch, because adequate levels of folate and B12 may regulate levels of homocysteine, an amino acid associated with heart disease and stroke. And folic acid deficiency is associated with neural tube defects in utero it’s recommended that pregnant women take doses as high as 5 mg daily. As a bonus, B12 may also play a similar protective role.
What’s going on?
What the experts say
“Both maternal and post-weaning folic acid supplementation in rat pups increased the risk of breast cancer in the offspring about twofold. Also, a Scottish study showed mothers given folic acid during pregnancy had, in 20 to 30 years, an increase in cancer deaths. But this study was methodologically flawed. Once a tumour is initiated, folic acid can promote a full-blown cancer before a tumour is initiated, folic acid can prevent initial transformation. A 2009 study looked at people at risk for cardiovascular disease who were put on folic acid and B12 it found mortality went up with supplementation. B12 studies have been limited. We need to be careful about mothers and women of reproductive age. What is recommended is 400 mcg of folic acid per day.”
YOUNG-IN KIM, staff gastroenterologist, St. Michael’s Hospital, Toronto
“Evidence from the 80s suggests that higher levels of B12 than those considered normal are important for brain health. B12 and other Bs are depleted by stress. B12 and folic acid work together there’s nothing folic acid is needed for that B12 isn’t needed for as well. But the balance in multivitamins is way off – there’s a lot more folic acid than B12. B12 is an orphan as far as research is concerned. Manufacturers aren’t aware that they need to balance their B12 and folic acid. All Bs are needed in balance. Folic acid helps cells divide, as does B12. But the two aren’t fussy about which cells they divide, so if you have micro-tumours and cancer cells, it will help them divide the same as healthy cells.”
AILEEN BURFORD-MASON, immunologist, nutritionist, Toronto
“The connection between B12 and neural tube defects is less clear than the use of folic acid for prevention of neural tube defects. A number of studies show that women who have low B12 status when they get pregnant are at increased risk for having babies with defects, and others don’t show an association. But there are no clinical trials. And since B12 is usually given in a multivitamin, you have the issue of whether it’s the B12, the folic acid or something else that’s producing the beneficial effect. We’re still sorting that out. People of childbearing age rarely become B12-deficient if they have B12 in their diet. B12 deficiency can cause anaemia and, in severe forms, neurologic damage.”
JAMES MILLS, senior investigator, epidemiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland
“The rate of shrinkage of the brain in normal elderly is influenced by a person’s B12 status: those with low-normal B12 show twice the rate of shrinkage (atrophy) of those with high-normal levels. These effects occur well above the cutoff level normally used to define B12 deficiency. We did a randomized clinical trial in which we gave high doses of B12, folic acid and B6 to the elderly with mild cognitive impairment (MCI): the treatment reduced the rate of brain shrinkage by between 30 and 50 per cent. So the message is: if you want to protect your brain as you get older, make sure your B12 status is very good.”
DAVID SMITH, professor emeritus of pharmacology, U of Oxford, founding director, Oxford Project to Investigate Memory and Ageing (OPTIMA)
