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A Doctor’s Guide to Vitamin B12 Deficiency in Seniors

Written by Leslie Kernisan
 about the author
8 minute readLast updated April 5, 2023

Maintaining adequate nutrition is vital to seniors’ health. You may already be encouraging your aging parents to eat healthy and take a daily multivitamin, but did you know that many seniors may still end up developing a serious deficiency with one particular vitamin? It’s vitamin B12.

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As people grow older, they become increasingly susceptible to vitamin deficiencies. Experts estimate that up to 20% of people 50 and older may have a low intake of vitamin B12. It’s common, serious, and worst of all, it’s usually overlooked until it causes significant health problems.
Vitamin B12 treatments are safe and effective, as long as you catch the problem before permanent damage occurs. By learning the symptoms and risk factors now, you can help your parents detect the signs and get tested earlier.
Here’s everything you need to know about vitamin B12 deficiency symptoms in the elderly, including causes, treatments, and more.

What are the important benefits of vitamin B12?

Vitamin B12 — also known as cobalamin  helps the body make red blood cells and maintain the proper function of nerve cells.

Vitamin B12 benefits for seniors include:
  • Generating cell growth
  • Boosting cognition
  • Supporting bone health
  • Supporting the immune system

How does vitamin B12 deficiency cause harm to seniors?

The most common health issues in seniors related to low vitamin B12 levels are:
  • Anemia. This means a person’s red blood cell count is low. Red blood cells carry oxygen in the blood, so anemia can cause fatigue or shortness of breath. The breakdown of faulty red blood cells can also cause jaundice, which is yellowing of the skin.
  • Neuropathy. This condition occurs when nerves throughout the body aren’t working well. It can cause a variety of symptoms, including tingling, numbness, burning, poor balance, and trouble walking.
  • Cognitive impairment. Damaged nerve cells in the brain can result in memory problems, irritability, and even dementia.

What are the most common symptoms of vitamin B12 deficiency?

The most common signs of vitamin B12 deficiency in seniors include:
  • Fatigue
  • Anemia
  • Neuropathy
  • Memory problems
  • Walking difficulties
You may have heard that vitamin B12 deficiency can cause pernicious anemia. But in fact, it’s the other way around.
Pernicious anemia is a result of the body’s inability to make what’s called “intrinsic factor.” The body needs intrinsic factor to absorb vitamin B12. Without it, vitamin B12 levels eventually drop. This often causes anemia, though sometimes symptoms of nerve and brain problems develop first.

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How does the body obtain and process vitamin B12?

People get vitamin B12 through foods and supplements. Fish, eggs, milk, poultry, and fortified cereals have it. Daily multivitamins also have it, as do B12 supplements.
Once vitamin B12 is consumed, it’s digested and stored in three steps:
  1. It’s processed by acids and enzymes in the stomach and small intestine
  2. It’s absorbed by the small intestine
  3. It’s stored in the body, primarily in the liver
The vitamin B12 stored in your body actually meets your needs for a few years. Although vitamin B12 is essential, only a little bit is needed every day. Even if a healthy person stopped consuming vitamin B12, it could take a few years before the body showed signs of deficiency.
The recommended daily allowance of vitamin B12 for adults is 2.4 micrograms. Experts have estimated that a Western diet contains 5-7 micrograms of vitamin B12, and a multivitamin often contains 12-25 micrograms.

Why are seniors at risk for vitamin B12 deficiency?

As people get older, their ability to absorb vitamin B12 tends to decrease. This is because seniors often develop problems with the acids and stomach enzymes needed to process the vitamin.
Common risk factors for low vitamin B12 in seniors include:
  • Low levels of stomach acid, which can be due to weakening of the stomach lining, or to medications that reduce stomach acid
  • Medications such as metformin (prescribed for diabetes), which interferes with vitamin B12 absorption
  • Alcoholism, which irritates the stomach and is sometimes linked to a poor diet
  • Surgeries that remove parts (or all) of the stomach or small intestine
  • Any problem that causes poor absorption in the stomach or small intestine, such as ulcerative colitis or Crohn’s disease

Why is vitamin B12 deficiency often missed in the elderly?

Vitamin B12 deficiency is often missed in seniors for two reasons:
  1. The symptoms are overlooked. The signs of vitamin B12 deficiency are quite common in older adults and can easily be caused by or attributed to something else.
  2. It progresses very slowly. Many people often go through a long period of being mildly deficient. During this time, a senior may barely notice their symptoms, or think the symptoms could be caused by another chronic health condition.
Still, a mild deficiency will almost always get worse over time. And even when a senior has many other causes for fatigue or problems with mobility, it’s good to fix the aggravating factors.
Unlike many problems that affect seniors, vitamin B12 deficiency is quite treatable. First, you need to make sure it’s detected. Second, you need to make sure the treatment plan has raised their vitamin B12 levels and that they’re kept steady.

When should you check for vitamin B12 deficiency?

Your parent should probably be checked for vitamin B12 deficiency if they’re experiencing any of the common signs or are at risk.
Experts recommend checking vitamin B12 levels especially if you’ve been concerned about:
  • Memory
  • Brain function
  • Neuropathy
  • Walking
  • Anemia
To make sure that a mild vitamin B12 deficiency hasn’t been overlooked, you can have your loved one proactively tested for low vitamin B12 levels. If your parent is suffering from any common risk factors associated with this condition, it’s best to have them tested as well.
Common risk factors for developing vitamin B12 deficiency include:
  • Following a vegetarian diet
  • Having stomach issues
  • Having pancreas issues
  • Having intestinal issues
  • Being on medication to reduce stomach acid for a long time

How is vitamin B12 deficiency diagnosed?

The first step in checking for deficiency is a blood test to check the serum level of vitamin B12.
Because folate deficiency can cause a similar type of anemia — megaloblastic anemia, which means a low red blood cell count with overly large cells — doctors often test the blood for both folate and vitamin B12. However, folate deficiency is much less common.

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It’s quite possible to have clinically low vitamin B12 levels without having anemia. If a clinician declines a request for a vitamin B12 check because an older person had a recent normal blood count, you can share this research article with them from The New England Journal of Medicine.
If the vitamin B12 level is borderline, a confirmatory blood test can be ordered. It’s called methylmalonic acid, and it’s higher than usual when people have vitamin B12 deficiency.
If the blood tests confirm a vitamin B12 deficiency, the doctor will prescribe vitamin B12 supplementation. The doctor may also recommend additional tests or investigation to find out why your parent has developed low levels of vitamin B12.

What are the treatments for vitamin B12 deficiency in seniors?

The initial treatment for a significant vitamin B12 deficiency involves an intramuscular shot, but oral vitamins can be given too. The options include:
  1. Intramuscular shots of vitamin B12 (1,000 micrograms). This bypasses any absorption problems in the stomach or intestine.
  2. High-dose oral vitamin B12 supplements (1,000-2,000 micrograms a day) have also been shown to raise levels, because high doses can usually compensate for the body’s poor absorption. However, oral treatments likely take longer to work than intramuscular shots, so they’re not ideal for initially correcting a deficiency — although they’re sometimes used to maintain vitamin B12 levels.
Most seniors prefer oral supplements over regular vitamin B12 injections, which is understandable — getting shots isn’t fun. However, taking supplements orally requires seniors to take their supplement consistently every single day. If your parent has difficulty taking medications regularly, scheduled vitamin B12 shots might be the better option.

Can high levels of vitamin B12 be dangerous for seniors?

The good thing about vitamin B12 treatment is that it’s extremely unlikely to overdose on vitamin B12. Unlike some other vitamins, vitamin B12 doesn’t cause toxicity when levels are high.
If your parent is being treated for vitamin B12 deficiency, you don’t need to worry that the doctors will overshoot. You just need to make sure a follow-up test has confirmed better vitamin B12 levels. Your family can then work with the doctors to find the right maintenance dose to prevent future vitamin B12 deficiency.

Are there other benefits of taking vitamin B12 supplements?

Since we know vitamin B12 is necessary for proper functioning of red blood cells and brain cells, you might be wondering if your parent should take higher doses of vitamin B12 as part of a healthy aging approach to prevent conditions related to vitamin B12 deficiency?
This preventive approach certainly doesn’t hurt. But once an older person has a good level of vitamin B12 in the body, it’s not clear that additional vitamin B12 will reduce the risk of problems like cancer or dementia. To date, much of the research on the benefits of extra vitamin B12 has been inconclusive.
However, research has definitely confirmed that a deficiency in this essential vitamin is harmful: The greater the deficiency, the more harm that’s done.
You can help your parents avoid problems by asking the doctor to check vitamin B12 if they exhibit a related symptom, or by requesting a proactive check if your parent has any risk factors.
Our aging parents have enough health problems to deal with. Let’s protect them from the ones that are easily detectable and treatable.


Meet the Author
Leslie Kernisan

Leslie Kernisan, MD, is a practicing geriatrician who believes that it shouldn't be so hard for older adults and families to get the right kind of help with healt.h concerns. For more practical tips — and to get her free, quick guide to checking aging parents — visit her at BetterHealthWhileAging.net

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