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Vitamin B12 Deficiency Can Cause Cognitive Problems

Older people are at risk for vitamin B12 deficiency, which can lead to cognitive difficulties. Certain medications and a vegetarian diet increase the risk.

As people grow older, they may begin to have difficulty with memory or complex cognitive tasks. The family might chalk the problem up to encroaching dementia due to aging. In some cases, though, cognitive decline could be caused by vitamin B12 deficiency, or possibly just a relative reduction.

Do Low Levels of Vitamin B12 Put Older People at Risk?

Q. My 90-year-old mother lost her marbles quite rapidly. Thank goodness a neurologist tested her vitamin B12 level. He said her level was “within normal range,” but that some older people need more B12 than “normal.”

On hearing that, I gave her OTC sublingual vitamin B12 pills every morning before breakfast. Nearly a week later, she shook herself and said, ‘I was really crazy, wasn’t I?’

She went on to enjoy the remaining months of her life and died peacefully from unrelated causes. Before passing, she declared, ‘I’ve lived long enough; it’s somebody else’s turn.’ Vitamin B12 made the difference between a dignified end-of-life and pure hell for everyone.

This is a pet cause of mine. I used to work in a nursing home, and I seriously wonder how many people end up in such a place due to a simple undiagnosed vitamin deficiency. Especially if a person seems to go senile very quickly, check their vitamin B12!

A. Older people are vulnerable to vitamin B12 deficiency. That’s because their stomachs may not make enough acid, or they may be taking powerful acid-suppressing drugs (proton pump inhibitors). The body needs acid to absorb vitamin B12. Metformin can also deplete the body of this crucial vitamin (see below).

Symptoms of this B vitamin deficiency may include difficulties with balance, numbness and tingling of the feet or hands, loss of appetite, memory problems, burning tongue, weakness, constipation or confusion. Restoring vitamin B12 with oral supplements, a transdermal patch or injections usually corrects the problem.

Vitamin B12 Levels in Older Adults:

Q. My husband (age 70) was just diagnosed with a vitamin B12 deficiency. Why is a B12 test not a part of regular blood work after a certain age? The symptoms mimic dementia and myriad other illnesses, including depression and anxiety. He’s gradually getting better after a month on vitamin B12 supplements.

A. You are correct that vitamin B12 deficiency is common among elderly people (Journal of Nutrition, Health & Aging, Feb. 2015). We don’t mean to imply that your husband is elderly. However, a Canadian study found that older men who get more vitamin B12 from their diets are less likely to be depressed (European Journal of Clinical Nutrition, March 2016).  Your point is well taken.

Determining Deficiency:

Testing for vitamin B12 is not a simple blood test, though. The diagnosis may require a test for methylmalonic acid (MMA) as well as serum B12 (cobalamin) (Journal of Nutrition, Health & Aging, March 2011). Doctors should consider such testing for people with symptoms of cognitive decline.

According to Dr. Tieraona Low Dog, people over 60 are at particular risk of vitamin B12 deficiency. She notes that certain medications increase that risk. To learn more about how B vitamin deficiencies can lead to depression, weakness and other problems, you may wish to consult her book, Fortify Your Life: Your Guide to Vitamins, Minerals, and More.

Vegetarians at Risk for B12 Deficiency:

We frequently discuss the benefits of a plant-based diet. Many nutrition experts recommend this approach to feeding ourselves and our families.

There are a few nutrients that may be in short supply in a vegetarian diet, however. Perhaps the most critical is vitamin B12. A deficiency of this crucial B vitamin can have devastating consequences for health and may require high-dose supplementation.

Q. About three years ago I woke up to find that I had lost some muscle control in my right leg. When I walked, my foot would flop.

My doctor did blood tests and diagnosed a vitamin B12 deficiency. After weekly B12 shots and daily B complex pills my symptoms went away. It took about three months. I still take monthly B12 shots.

Why don’t you ever stress the importance of this vitamin for vegetarians? You cannot get B12 from vegetables.

Overcoming a Vitamin B12 Deficiency:

A. Vegetarians, especially vegans who get no eggs or dairy products, may need to take vitamin B12 to prevent deficiency. You are correct that vegetables and other plant foods do not contain vitamin B12.

Drugs That Increase the Risk of B12 Deficiency:

Anyone taking metformin for diabetes or an acid-suppressing drug for reflux (esomeprazole, lansoprazole, omeprazole, etc.) should also be alert for this danger. People with celiac disease, an intolerance for gluten found in wheat, barley and rye, are also at risk.

Are You Getting Enough Vitamin B12?

Vitamin B12 deficiency can cause nerve damage, confusion, depression, irritability and poor muscle control. Detecting a deficiency may require a test for methylmalonic acid (MMA) as well as for vitamin B12.

Although vitamin B12 (cyanocobalamin) shots were traditionally used to counteract vitamin B12 deficiency resulting from lack of intrinsic factor in the stomach to facilitate absorption, oral supplements in high doses such as 1,000 micrograms (1 mg) or sublingual supplementation can also be effective. For oral supplementation, some doctors prefer to prescribe methylcobalamin.

Overcoming Vitamin B12 Deficiency Caused by Metformin:

Q. I developed numbness and tingling in my feet due to vitamin B12 deficiency after taking pantoprazole and metformin for several years. I had received no warnings from my doctors about potential vitamin B12 deficiency and only found out during a yearly blood-screening test.

My doctor wanted me to take vitamins, but to heck with taking pills to cover up problems from other pills. I was able to get off pantoprazole, with some serious effort. What can I do for my diabetes?

A. Metformin is prescribed for diabetes, while pantoprazole (Protonix) is a proton pump inhibitor (PPI) used to suppress stomach acid production and treat severe heartburn or GERD (gastroesophageal reflux disease).

Consequences of Vitamin B12 Deficiency:

Both metformin and PPIs reduce the absorption of vitamin B12 from the stomach, which is why people must be tested for deficiency. Lack of vitamin B12 can lead to depression, irritability, confusion, poor muscle control and nerve damage that produces symptoms of numbness and tingling like yours. Constipation, loss of appetite and anemia are other possible symptoms. Lasting neurological damage is rare but may happen if the deficiency is not addressed.

The combination of a PPI with metformin may increase the possibility of this complication. We have heard of it happening before, as we wrote here.

The Usual Treatment Is Vitamin Supplements:

Generally, the treatment for vitamin B12 deficiency is supplemental vitamin B12 to replace the lost stores of this critical nutrient. This used to be delivered as a monthly cyanocobalamin injection. Research has shown, however, that taking a high-dose vitamin B12 orally (such as a 1 mg tablet) can also counteract poor absorption (Clinical Medicine, April, 2015).

Metformin may be the best treatment for your type 2 diabetes. There are, however, some other approaches that may allow you to reduce your dose of medication by concentrating on diet, exercise and stress relief along with certain botanical extracts. You can learn more about metformin as well as such nondrug approaches to controlling blood sugar in our Guide to Managing Diabetes.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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  • Couderc AL et al, "Cobalamin deficiency in the elderly: aetiology and management: a study of 125 patients in a geriatric hospital." Journal of Nutrition, Health & Aging, Feb. 2015. DOI: 10.1007/s12603-014-0525-1
  • Gougeon L et al, "Intakes of folate, vitamin B6 and B12 and risk of depression in community-dwelling older adults: the Quebec Longitudinal Study on Nutrition and Aging." European Journal of Clinical Nutrition, March 2016. DOI: 10.1038/ejcn.2015.202
  • Chatthanawaree W, "Biomarkers of cobalamin (vitamin B12) deficiency and its application." Journal of Nutrition, Health & Aging, March 2011.
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