Which medications affect the absorption of vitamin B12?

Preventive Medicine Specialist David Katz, MD, explains which medications can affect the absorption of vitamin B12. Learn more information on preventive medicine and overall wellness.

Transcript

00:00

Aspirin is associated with erosions of the stomach or gastritis. And that inflammation of the stomach lining can be enough to interfere with B12 absorption.

00:15

B12 is complicated when it comes to getting it from food or from an oral supplement into our bloodstream. There's more going on there than with most nutrients.

00:24

For one thing, B12 comes bound to other proteins. And so the first thing we have to do is cleave it. And that's fairly common.

00:31

You have to break nutrients into smaller parts. But you need good stomach function to do that. You need a normal level of stomach acid.

00:38

And you need the stomach to behave normally. And then the other thing you need is another protein called intrinsic factor secreted

00:45

by the stomach to bind B12 and escorted into the bloodstream. That's unusual. So if any of that goes wrong, you

00:52

can't get B12 from food or supplement from your stomach into your bloodstream. So a number of drugs can interfere with that.

00:59

The obvious ones are medications that affect the stomach lining or stomach function. One of the most common is aspirin.

01:06

Aspirin is associated with erosions of the stomach or gastritis. And that inflammation of the stomach lining can be enough to interfere with B12 absorption.

01:15

Now, of course, this doesn't mean stop taking aspirin. You may be taking aspirin to reduce your risk of a heart attack. You don't want to just stop.

01:21

But if you have symptoms of B12 deficiency that you are overlooking and you're taking aspirin, well, you may have cause and effect there.

01:28

And extra B12, either orally or by injection, to get around the problem may be important. Another commonly used class of medication

01:35

that can interfere with B12 absorption is anything intended to reduce stomach acid production. That's the whole family of medications

01:42

for treating heartburn or GERD and for treating ulcers. And of course, most important on that list are the medications that do that job most potently,

01:50

the proton pump inhibitors. These are medications that really shut off the pump that puts acid into the stomach.

01:57

No stomach acid, can't absorb B12. B12 deficiency tends to be a problem. And these are medications that are commonly prescribed

02:04

and often taken for years. And then another one that is a culprit-- and this one's a little bit odd-- is metformin.

02:10

It's a diabetes medication marketed most commonly as glucophage. And here we don't entirely understand the mechanisms.

02:16

There's speculation in the literature that it's an effect of the medication on the intestines. Anyone who's taken glucophage knows

02:25

that the rate limiting side effect tends to be some gastrointestinal upset. So something about the mechanism on the intestine

02:31

is interfering with B12 absorption. That's less of a common problem, but it can occur. And then there are others, but they're more esoteric.

02:38

There are antibiotics that people are rarely prescribing these days. So the total list is long. But those are the ones on the top of the list.

02:45

They're commonly used. B12 deficiency is common. And so the overlap between use of these medications and B12

02:52

deficiency is also common. If you're taking these medications and are concerned about your B12 level, you should get it checked.