science of us

Do You Need More Vitamin B12?

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Despite having reminded myself, several times over, that the vast majority of dietary supplements don’t really do much, and that most of us get most of what we need naturally, I still enjoy the occasional vitamin-related panic. B12, for instance. I remember prescribing myself vitamin B12 during a prolonged period of panic attacks in my mid-20s, and I don’t recall it doing much to help — but what if it did, and I forgot? Depending on whom you ask, B12 can reduce anxiety, boost your energy, and improve your skin. And because vitamin B12 is naturally found in animal products, some warn against vegan or vegetarian diets. To find out what vitamin B12 does, who (if anyone) needs more of it, how to get more of it, and how vegans and vegetarians are impacted, the Cut spoke to Despina Hyde Gandhi, a registered dietician and diabetes educator at NYU Langone Health.

I’m a vegetarian. Do I need to take a vitamin B12 supplement?

The best place to get vitamins is naturally from foods versus supplements, but if someone is deficient in vitamin B12, their levels can be restored with a supplement. But usually, people are getting enough B12 from their diet, even vegetarians. B12 is mostly found in animal products, but it is also in fortified foods like cereals and non-dairy milks. It’s in our foods in a fortified level, even when it’s not naturally occurring. If a vegetarian is open to eating eggs, they can get plenty of B12 from that, whereas someone who follows more of a vegan diet may be getting less B12, and may benefit from supplementation, but usually they’re able to get enough from the diet.

How do vegans get vitamin B12?

There are places where a vegan can get B12, like in fortified cereals and fortified nondairy milks. A lot of vegan patients may be using something called nutritional yeast to replace the flavor of cheese in their food, and that is also a source of B12. So definitely there are places in the diet where vegans and vegetarians can get B12.

Who should take a vitamin B12 supplement, if anyone?

B12 is absorbed through something called intrinsic factor that’s produced in the stomach. So if somebody had a gastric surgery, like a weight-loss surgery or something like that where their ability to make intrinsic factor is compromised, we may recommend B12 supplementation. The elderly or aging population may need additional B12 supplementation. But most adults are getting enough B12, even vegetarians.

What does vitamin B12 do for you? Is it important for my brain?

It does help with our nerve function, which plays a huge role with our brain function, but it also helps our body make DNA, which is super-important, and it helps with proper development of red blood cells. So you might hear B12 associated with certain types of anemia, like pernicious anemia. So if someone is feeling really tired, and [the cause] is related to pernicious anemia, B12 can be helpful.

Where it’s not helpful, and where there’s not a lot of good research, is in showing that B12 can increase energy levels in someone who already has normal B12 levels. I think a lot of times people think, “Oh, I need to get a B12 shot,” but it’s not really going to do much for the person who has normal levels of B12.

How much B12 should we be getting?

So for most adults, it’s 2.4 micrograms. It’s slightly increased in pregnant or lactating women — it might go up to 2.6 or 2.8. The supplements you’ll see are at levels of maybe 1,000 micrograms, because we can only absorb a small amount of the supplement. We’re not really absorbing all of it. [The National Institute of Health provides a handy, fascinating chart on the amount of B12 we get from various food items, like canned tuna, which provides 2.5 micrograms per serving, or a hard-boiled egg, which provides 0.6 micrograms.]

Is it possible to take too much B12?

B12 is a water-soluble vitamin, so we don’t store what we don’t use, so it just gets excreted in the urine. It’s a very, very low likelihood that you could take too much B12.

How do you know if you’re getting a good B12 supplement, since most dietary supplements aren’t FDA regulated?

It’s hard because we don’t have a lot of regulation, but sometimes patients like to do a food-based supplement, which means that it’s not a lot of different chemicals, it’s actually from real, powder-ized foods. Supplements are tricky, and you have to do your research. I work with a lot of weight-loss surgery patients who do need supplementation, so I’ll usually call the company and ask around about how things are manufactured. If you’re just taking regular, daily multivitamin, that might not be so much of a concern, but if you’re somebody that suffers from chronic, low B12 levels, you may want to spend some time researching the product you’re using.

It sounds like most people who need B12 supplements will be told so by their doctors, but is there another way to find out if you need more B12?

It’s actually a very easy test when you do blood work. A lot of times doctors automatically check vitamin D levels, so you could always ask to have B12 checked too. It’s pretty simple and inexpensive.

Do You Need More Vitamin B12?