Should I take vitamin B12 supplements as I get older?

The older you get, the greater your chance of a B12 deficiency -- even if you eat perfectly well. Two processes play a role in this. A small protein in the kidneys and intestines that absorbs and recycles B12 works less efficiently with age. In addition, 10 to 15 percent of people over 60 develop deterioration of the stomach lining, which causes less stomach acid to be produced. This makes it harder for B12 from food to be released properly. Both processes develop gradually and without obvious symptoms.

Good news if you are affected by that deteriorating stomach lining: B12 from supplements or fortified foods does not require stomach acid. That form is released directly. Studies show that 1000 micrograms per day works just as well as injections for restoring blood levels¹. No side effects are known. One caveat: if you already have an untreated deficiency, a high intake of folic acid through fortified foods can worsen neurological damage. That is a reason to check your B12 status, not to avoid supplements.

On the question of protection against memory problems, the picture is less clear. There is an association between low B12 levels and cognitive problems, but that association disappears in some studies once you correct for age and education. B12 alone is not demonstrably linked to a lower risk of dementia. When combined with B6 and folic acid, a small effect on memory scores has been found in older adults without dementia -- but only with use lasting longer than 12 months. In people who already have dementia, it does not work.

At the cellular level, laboratory studies suggest that a B12 deficiency contributes to DNA damage and poorer energy production in cells². In a mouse study, B12 supplementation protected the kidneys against age-related damage³. Interesting, but these findings have not yet been translated into proven effects in humans.

There is no official guideline that prescribes screening all older adults. Nevertheless, experts advocate for it, given the gradual onset and the safety of supplements. If you want to know whether you have a deficiency, do not only have your B12 blood level measured, but also your methylmalonic acid (MMA). That provides a more reliable picture.