Not having enough vitamin B12 can shrivel your brain. No, really.

Anyone ever told you that if you don't get your vitamins, your brain will shrink? No? Well they should. It turns out that having a vitamin B12 deficiency later in life is pretty bad for your grey matter. A group of researchers looked at over-65s from the South Side of Chicago, and measured the amount of vitamin B12 and B12-related metabolites in their blood, their cognitive skills, and took MRIs of them.

The subjects who had the markers for B12 deficiency also had lower scores on their cognitive tests and smaller total brain volume.

What's interesting is that the level of B12 itself in the blood wasn't linked to any loss of cognitive function, but the metabolites that mark its deficiencies were — which raises the question of whether it's as simple as diet and vitamin supplements to help prevent or reverse this change, or if there's a larger underlying issue.