Common Lack of Vitamin B12 Linked to Depression and Memory Loss

Vitamin deficiencies are supposed to be a thing of the past. But a lack of vitamin B12 may be surprisingly common.

Most people don’t think twice about this nutrient, also known as cobalamin. Vitamins B, C and D are sexier and get more attention. But inadequate levels of vitamin B12 can have devastating consequences, including depression and memory loss.

One reader wrote:

“I want to warn your readers about my experience with tetracycline. This antibiotic was prescribed by a dermatologist to keep my skin clear and I took it for years.

“Gradually I began having difficulties such as burning, tingling and numbness in my fingers and feet. I lost a lot of hair, which was once my best feature. Even worse, my short-term memory became very poor. I am an attorney and this affected my work.

“I was having trouble walking when I noticed a poster in the pharmacy describing the symptoms of vitamin B12 deficiency. I realized that I had all of them. When I was tested, the doctors were astonished that my B12 levels were so low.

“They started vitamin B12 injections twice a week and then gradually changed me to twice a month. My hair has grown back and my nerve problems are much better, though not perfect. The tetracycline was the culprit.”

It took a long time for this woman’s problem to be diagnosed. Her doctors had not considered the possibility that her many symptoms could be due to a drug-induced lack of cobalamin.

Symptoms of Low Levels of Cobalamin Include:

anemia, nerve damage (burning, tingling, weakness or numbness in hands and feet), difficulty in sensing vibration, unsteadiness and psychological side effects. Depression, confusion and poor memory may be mistaken for early onset of Alzheimer’s disease.

This vitamin deficiency often appears very gradually. Patients may describe complaints such as mental fuzziness or poor coordination for months before a proper diagnosis is made.

Medications That Can Trigger a Lack of Vitamin B12:

Few people realize that certain medications can interfere with the absorption of this crucial nutrient. Acid in the stomach is essential for this function, so long-term use of strong acid-suppressing medications such as Aciphex (rabeprazole), Nexium (esomeprazole), Prevacid (lansoprazole), Prilosec (omeprazole), or Protonix (pantoprazole) may contribute to a problem for some individuals, especially when taken for a long period of time. We recently received a query from a reader concerned about depression and memory deficits associated with one of these drugs.

Could PPIs Deplete the body of Vitamin B12?

Q. I am taking Prilosec daily for Barrett’s esophagus. The doctor who prescribed it told me this would be for the rest of my life to prevent cancer. I have read that there is a risk of triggering depression and some memory issues. I am concerned about both.

A. Studies that have assessed the cognitive effects of proton pump inhibitors (PPIs) like omeprazole have produced contradictory results (International Journal of Molecular Sciences, Nov. 29, 2024).  If PPIs deplete vitamin B12 levels, though, that could negatively affect both memory and mood. The official prescribing information does mention depression under the “Postmarketing Experience” listing.

Other Drugs That Affect Vitamin B12:

The diabetes medicine Glucophage (metformin) can also lead to problems with vitamin B12. Anyone taking this drug should be monitored very carefully and supplementation may be necessary. Potassium supplements such as Slow-K, Micro-K, Kaon Cl, K-Tab and Klor-Con can also wreak havoc with cobalamin levels.

Using both metformin and a PPI, as many people do, can exacerbate the lack of vitamin B12 (Diseases, Oct. 10, 2025). The researchers noted that serious problems resulting in hospitalization were more common among elderly patients taking this combination.

Even with just one medication, older people may be especially susceptible to a lack of vitamin B12. As we age, the stomach can become less acidic. It may also stop making a key chemical called intrinsic factor, which promotes vitamin B12 absorption.

Seniors are not the only vulnerable population. Vegetarians, especially teenage girls who are not as nutrition savvy, may also suffer. Dutch researchers recently reported adolescents on a strict vegetarian diet performed poorly on a battery of tests designed to evaluate mental ability and coordination.

You may think vitamins are boring, but the consequences of a deficiency are devastating. Sometimes even a well-balanced diet cannot overcome the vitamin-depleting effects of medication. In such cases, supplementation becomes necessary.