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Why You Might Need More B12 and D3 Vitamins

Two dietary supplements that may make sense for older adults

photo of a gold colored chewable vitamin d three supplement and a dissolvable vitamin b twelve supplement

Jamie Chung

En español | You already know you should eat a wide array of fruits and vegetables, topping them off with a moderate amount of healthy oils, whole grains, lean meats and dairy.

But even if you're eating a perfect diet, you may still be coming up short in two essential nutrients: vitamin B12 and vitamin D3. And you may want to consider supplements.

Now, it's true that most vitamin supplements fail to deliver a measurable benefit. “When you take things out of the food matrix and you put a single ingredient into a pill, it doesn't have the same effect,” says Katherine Tucker, director of the Center for Population Health at the University of Massachusetts Lowell. The U.S. Preventive Services Task Force says there isn't enough evidence to support even a daily multivitamin to prevent cancer and heart disease. That's why it's better to think plants, not pills.


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But B12 and D3 are different, for two reasons. First, you can't really get them from plants. And second, as we get older, we begin to develop difficulty absorbing them in their natural form.

Understanding B12

This vitamin plays an essential role in nerve function; a shortfall of B12 is associated with depression, dementia and decreased cognitive function, as well as anemia.

Unless you're a vegan, getting enough dietary B12 isn't a problem, because burgers, steaks, chicken, eggs, dairy and other animal products are rich in it. But as we get older, our ability to absorb B12 is hindered by changes in our digestive systems, as our stomachs naturally begin to produce less stomach acid. Antacids and diabetes medications can exacerbate the problem. Digestive issues such as celiac disease also can hinder our ability to access B12. The general term for these issues is “malabsorption.”

"Malabsorption issues can arise at different ages. But generally, people should start paying attention to this after age 50,” Tucker says. By age 65, as many as 4 in 10 adults may have gastric issues that hinder B12 absorption.

The federal dietary guidelines call for a daily intake of 2.4 micrograms of B12 for all adults. But discuss your diet and your underlying health issues with your doctor before deciding on a B12 supplement. You can buy pills that deliver up to 1,000 micrograms per dose, but does it make sense to pay more for a megadose your body doesn't need?

The details on D3

As little as 10 to 15 minutes in the direct sun a few days a week can give us most of the vitamin D our bodies need to maintain a healthy immune system, bones and muscles while protecting us from cognitive decline. So what's the problem? Well, our ability to turn sunlight into vitamin D declines as we age.

That's partly because the precursors to vitamin D production found in the skin are reduced. By age 70, our ability to produce vitamin D is about half of what it was at age 20. And unlike B12, D is in scarce supply in our regular diets. Most milk and some juices, milk alternatives and cereals are fortified with D, but other dietary sources — fatty fish like mackerel and sardines, and some mushrooms — aren't exactly a staple in most diets. As a result, nearly 1 in 4 people in the U.S. have inadequate blood levels of vitamin D.

That's a problem: As vitamin D levels decline, the risk of Parkinson's, Alzheimer's and cognitive impairment rises. Vitamin D also serves as an air traffic controller for calcium, essential for bone health. In one study of adults 50 and older, all of whom had recently fractured bones, 43 percent were deficient in both calcium and vitamin D.

Before you pick up a vitamin D supplement, it makes sense to have a conversation with your doctor. Vitamin D can interact with heart medications, including statins and diuretics. Dietary guidelines call for 600 international units (IUs) daily of vitamin D (and at least 800 after age 70). So that's a solid place to start. Look for vitamin D3, which is more efficiently utilized by the body than D2.

AARP Executive Editor Stephen Perrine is author of the forthcoming AARP book The Whole Body Reset.

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