Oral B12 supplements help correct a deficiency better than injections

A deficiency in vitamin B12 can cause some pretty serious health issues. Including problems with your cognition, your immune system, and even your heart.

And for a long time, doctors opted to give B12 injections to patients deficient in this key nutrient—rather than have them rely on oral supplementation, due to concerns that the human body doesn’t do a good job absorbing it orally.

But now, a new study has found that’s just not true. In fact, it turns out, B12 supplements work far better than injections to correct B12 deficiencies…if you use the right doses.

RDAs fail to prevent B12 deficiencies

The government’s Recommended Daily Allowances (RDAs) are supposed to make sure that no one suffers from a “frank” nutritional deficiency. Yet—deficiencies in B12 are still quite common. Especially among older people and people who follow vegan or vegetarian diets.

And there are two main reasons …

First, certain common medical conditions and prescription medications can cause B12 deficiencies. For example, metformin is the first-line prescription drug for Type II diabetes. It originally derives from a plant, but it can also cause a deficiency in B12.

Second, B12 (like all the B vitamins) is water-soluble—meaning, it doesn’t build up in your tissues, and you have to replace it daily.

Fortunately, you can add B12 into your diet by eating wholesome, healthy foods like eggs, red meat, and milk. But—as I explained earlier this week—millions of men and women still think they’re following doctor’s orders by limiting these nutritious foods. So, over time, these unhealthy restrictions can contribute to a serious B12 deficiency.

New thinking about B12 injections

The idea of relying on B12 injections to correct a deficiency dates back to the 1940s. Doctors saw it as a way of getting around the supposed problem of poor absorption of B12 in the gastrointestinal (GI) tract. But most of the early research studying oral B12 used doses that were way too small—only 6 to 160 micrograms (mcg). (Yet another case where doctors use doses of micronutrients that are far too small!)

So, when the doctors didn’t see the patients’ B12 blood levels rise after oral supplementation, they assumed it must all stem from poor absorption in the GI tract.

But that’s not the entire story.

Basic biochemistry still applies—regardless of absorption issues. In other words, if you don’t use a high enough oral dose of B12, the vitamin still won’t move from an area of higher concentration (in the GI tract) into an area of lower concentration (in the bloodstream).

Plus, we do have existing research to support the use of oral supplementation…

Back in 1968, Swedish researchers followed 64 patients with a clinical B12 deficiency who began taking 500 to 1,000 mcg of oral B12 daily. During the five-year study, 100 percent of the participants’ B12 levels normalized, including hemoglobin and hematocrit (which measure red blood cells).

As a result, Sweden adopted the widespread practice of administering sufficient oral doses of B12. But in the U.S., we kept giving deficient patients injections. (Side note: About 30 years ago, Sweden stopped the practice of fortifying foods with iron, in part, based on my research with Nobel laureate Baruch Blumberg and others. But I suppose you can’t be a prophet in your own land—although the Nobel Prize is awarded by Sweden.)

Then in 1998, U.S. researchers conducted a similar, but stronger study—with a control group—on 38 people with a B12 deficiency. This time, researchers randomly divided patients into two groups. The first group got 2,000 mcg of oral B12 daily for four months. The second group got 1,000 mcg of B12 as an intramuscular (IM) shot at the beginning of the study, and then once a month for four subsequent months.

It turns out, the people who took the oral supplement achieved B12 blood concentrations that were more than three times higher than those achieved with the repetitive IM shots.

A science-backed changing of ways

I remember during the 1960s and 1970s, my grandparents in France went dutifully to their doctor’s office regularly to get their vitamin B12 shots. They both lived long, healthy lives. In fact, my grandfather was a veteran of the French Navy in WW I and the Free French Resistance in WW II, and he died on the 50th anniversary of D-Day in 1994 at the age of 97. And his father (my great-grandfather) lived until the age of 98.

Maybe it was genetics. And maybe it was the B12.

But based on this new evidence, it seems to me that my grandparents probably could have just taken a high-quality, high-dose B12 supplement…rather than going through the hassle of taking shots.

Plus, even today, oral B12 is much less costly than IM shots—only a few dollars each month! And it’s certainly much easier on the patient to take a B12 supplement than getting a shot.

If you have a B12 deficiency, I suggest you speak with your doctor about the science-backed benefits of oral supplementation. And even if you don’t have a frank B12 deficiency, you should still supplement daily with a high-quality vitamin B complex. It will help support your sleep, your heart, and your neurological health. Subscribers can also search my archives for more clear benefits of B12. So if you haven’t already, become one today!


“Treating Vitamin B12 Deficiency: What Formulation Is Best?” Medscape, 3/9/20. (medscape.com/viewarticle/926301_2)