The People's Perspective on Medicine

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.
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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. .
Fortify Your Life: Your Guide to Vitamins, Minerals, and More

Fortify Your Life gives you the evidence-based information you need to decide whether you need a supplement and which format and dose would be best.

Fortify Your Life: Your Guide to Vitamins, Minerals, and More
  • 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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Joe and Terry,
No need to apologize for implying that someone is elderly. I am 76, and ask: What’s wrong with being elderly? When young people express negativity about getting old, my response is to say, “Guess what, boys and girls, you might not have to worry about it.” Old age is a privilege denied to many.

All the information above is true. but another issue is that some people are not able to absorb B12 in the cyancobalamin form at all. One reason is that some people can no longer absorb it in their stomach as they age or have pernicious anemia, an autoimmune disease. Another reason is that they have a genetic issue with the process of absorbing cyancobalamin. After struggling for years with profound fatigue (I had enough B12 in my blood), my integrative physician tested me for the MTHFR variant. I have 2 genes of one variant. After researching this, I found it is relatively common in the general population.

Logic tells me that in the past, before enriched foods and supplements, this was not an issue. If you have this variation, you need methylcobalamin which is the type of B12 naturally found in food sources. If you are unsure, avoid food products and supplements with cyanocobalamin and if you use supplements, use them with methycobalamin form of B-12. They are in the stores but you have to search for them. They are more expensive than the cyanocobalamin.

Obtaining sufficient B12 is no problem for vegetarians– we need only to use a quality B12 supplement. And not a great amount of B12 is needed, either. The vegetarian diet contains all other nutrients needed in proper proportion.

There is a lot of false information. The test you need is Active B12. Serum B12 only tells you how much B12 you have in the blood, not how much is being used. 70-80% of Serum B12 is inactive. Unfortunately, doctors don’t test for this.

Vitamin B12 . When I was diagnosed I had zero B12 in my blood. How bad can bad be? I started monthly injections of B12. Well, after some “time” I started daily dosages of one pill 1,000 mg under the tongue. My blood test has been resulting in normal B12. My over all point is that there were tell-tale signs before I went to my doctor to complain that I just don’t feel right: was never warm enough even during the summer months (wearing sweaters); had brittle nails, dry hair; never feeling rested from sleep etc. There are books to read in your local libraries on the subject. It can run in families. My one daughter and son have the same problems.

Have been taking NOW B-100s for years. After looking at your numbers for B-12 and B-6, I wonder why a reputable firm would use 100 mcg of B-12, which is 4167% of the daily value, and 199 mg of B-6, which is 625% of the daily value! I have no fractures but now I’m beginning to wonder if I should look for lower doses. I’m 81 years old and in very good health.

I am 45 yrs old, and for last 18 years have been suffering from palpitation in head and heart. The problem started suddenly due to drinking alcohol, and the next morning when I got up my head had totally collapsed. I had sertaline for last 18 years and diazepam for last 5 years. Now I am suffering from movement control and difficulty in keeping balance. Doctor last week diagnosed for vitamin b12 deficiency. What to do?

A few years ago I thought I was experiencing early onset senility: depression, lack of concentration, near-paralysis when faced with decisions to make. It threatened to ruin my career. My doctor at the time told me it was stress and that I should “take it easy”. When I started waking at night with the painful sensation that my hands were three times their normal size (they weren’t) some tests (by a new doctor) were run which showed a vitamin B deficiency. A vit B trans-dermal patch weekly made an immediate and dramatic difference. I now use one once a month. Besides not eating much meat, we found no reason for the deficiency.

I think the form of B12 is important! I read that the B12 you take is important. Methylcobalamin is the better, the one that begins with C can be toxic to the liver! Sorry if spelling is incorrect! Remember, the one beginning with C has traces of cyanide in it.

My mother couldn’t walk down the middle of a hall. She would hit one wall and then the other. Being a nutritional consultant, I took her to a friend for a shot of B 12. Unbelievably, she was almost immediately able to walk straight down the hall. He had taken a blood test before the shot, and the test showed no deficiency.

I used to have many leg cramps and cramps in my lower chest muscles. If I was driving I had to immediately stop the car and get out to stretch. After testing found out I have a deficiency of the B 12, as I am also diabetic and have been taking metformin. So I started this vitamin and stopped getting cramps.

Do not find enough information/details here.

Bran cereal is a good source of B vitamins, plus several others.
I add water, cinnamon, and a sugar substitute and microwave it. Not bad.
Plenty of fiber and other good stuff.

I am near 80 and my physician’s assistant at the VA ran a series of blood test on me. One of the tests was for vitamin B12

The results were scary! I was TOXIC! I was near the 1700 range and normal is 900. I was taking the B12 sub lingual and was taking 1 tablet each day. Since I was TOXIC I have cut back to maybe 1 tablet a week. So far I can not tell the difference other then I have less leg pain.

When you speak of cognitive problems, does this include an inability to find the right word when you are speaking? My friends “play the game” of filling in my sentences for me as I am constantly losing words when I speak.

Can you overdose on B12 supplements?

Regarding low vitamin B12 conditions, NY Times last week reported that researchers have found that large doses are linked to an increased risk for hip fracture in older women. Recommended dietary allowance for healthy women over 50 is 2.4 micrograms of B12 and 1.5 milligrams of B6, which would be fulfilled by eating 6 oz. of cooked tuna (among many other foods).

Centrum Silver contains 50 micrograms of B12 and 5 milligrams of B6. An observational study reported in JAMA Network Open included 75,864 women and a 30 year followup showed that the more of either supplement was consumed, the higher the rate of fracture, especially when both were used together compared to those who took less than 2 milligrams of B6 and 10 micrograms of B12. Those who took more than 35 micrograms of B6 and 20 micrograms of B12 were 47% more likely to have a hip fracture.

You can find the brief article in the 6/11 Science section of the NY TImes.

HELP! How in the world can we balance the need and the danger?! Should I stop taking Centrum Silver? Are there supplements that contain less? I eat healthily but worry that at 80 I may be getting fewer nutrients out of “real” food than I used to.

The article on vitamin B12 was interesting. Is dairy the only food containing B12. I do eat eggs and a bit of Greek yogurt. Are there any other foods containing B12? How much food should be eaten for sufficient intake of B12?

I have neuropathy. It began in the late seventies. Never had diabetes or chemotherapy. I understand it can be age-related as well. Learned from this site about benfotiamine, a synthetic form of B which I take 1000 mg per day. Acupuncture as well.

No more spasms down the leg, and symptoms of tingling and tenderness much reduced. If I forget for a couple of days, there is a big difference.

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