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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.

Vitamin B12 Deficiency 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.

Symptoms of B12 Deficiency:

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.

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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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