Should I take vitamin B12 supplements as I get older?

Vitamin B12 is an essential vitamin that the body cannot produce on its own and must be obtained through food or supplements. As people age, the risk of deficiency increases, even when they eat healthily. This is due to two mechanisms: first, the function of the protein 'amnionless' in the kidneys and intestines deteriorates with age, causing B12 to be absorbed and recycled less efficiently. Second, 10 to 15 percent of people over the age of 60 develop atrophic gastritis, a wearing down of the stomach lining in which less stomach acid and digestive enzymes are produced. As a result, B12 from food is released less effectively. Both processes occur gradually and are not dependent on how well a person eats.

The good news is that B12 from supplements or fortified foods is still well absorbed by people with atrophic gastritis, because this so-called 'crystalline' B12 does not require stomach acid to be released from food. Supplementation of 1000 micrograms per day was shown in studies to be just as effective as injections for correcting blood values such as haemoglobin and red blood cell size. The safety profile is good: B12 itself has no known side effects. There is one point of attention: in people with an existing but untreated B12 deficiency, a high intake of folic acid (through fortified foods) can worsen neurological damage. This is a reason to pay attention to B12 status, not to avoid B12 supplements.

On the question of whether B12 supplementation also prevents cognitive decline or dementia, the evidence is considerably less clear. There is an observational association between low B12 levels and cognitive problems, but this association disappears in some studies once corrections are made for age, education and other factors. Higher B12 intake on its own has not been demonstrably linked to a lower risk of dementia in large-scale research. When B12 is combined with other B vitamins (such as B6 and folic acid), a small but statistically significant effect has been found on slowing cognitive decline in non-demented older adults, averaging 0.15 points on a memory score, and only when used for longer than 12 months. No effect was found in people who already have dementia.

At the cellular level, laboratory studies suggest that B12 deficiency may contribute to DNA damage, impaired functioning of mitochondria (the 'power plants' of cells) and disrupted epigenetic regulation. In animal research, B12 supplementation protected rat kidneys against accelerated ageing damage. These findings are interesting but have not yet been translated into proven clinical effects in humans.

There is currently no official guideline prescribing routine screening of all older adults for B12 deficiency, partly because no fully standardised test exists. Nevertheless, experts advocate targeted screening, given the high prevalence of deficiencies, the gradual onset, and the safety and availability of supplements. The most reliable measure of deficiency is the blood protein methylmalonic acid (MMA), not just the standard B12 blood value.