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Vitamin B12 and You

I consider myself a pretty active guy. I do more at 49 than I did at 29 from a physical standpoint. I walk, I run, I ride a bicycle, I go to the gym, I exercise at home, I go to kickboxing classes…

Over the past 2 months or so, I have found that I am petering during my runs by the time I hit a mile. I have been blowing off kickboxing because I simply feel tired. Even my biking is way down this season.

A few weeks ago I had my annual physical. My doctor asked how I was feeling and I told him I mostly felt fine but a little more tired than usual. He grinned – he knew I would say that.

“Michael” he said. “Your blood work is just fine, but you are deficient in vitamin B12 (and vitamin D)”.

It’s interesting that in the past few years since getting in to physical fitness that I never read about B12 and how it can affect you. I have done a lot of reading since and learn more every day. I have started weekly B12 shots for 4 weeks (then monthly after that until he says otherwise).

So let’s talk about this B12 deficiency for a moment…

The human body needs vitamin B12 to make red blood cells, nerves, DNA, and carry out other functions. The average adult should get 2.4 micrograms a day. Like most vitamins, B12 can’t be made by the body. Instead, you must get it from food or supplements.As for food, B12 can not be found in vegetables. You find it in meat, poultry, eggs, dairy products and other animal products. If you are a strict vegetarian, you can be at a greater risk for this deficiency. But not to worry – you can get B12 in supplements, or grains that are fortified with B12.

Conditions that interfere with food absorption, such celiac or Crohn’s disease, can cause B12trouble, as can the use of prescribed heartburn drugs, which reduce acid production in the stomach (acid is needed to absorb vitamin B12). The condition is more likely to occur in older people because of the cutback in stomach acid production that often occurs with aging.

B12 deficiency can come on slowly, or rapidly (as it did for me). Many adults overlook this or confuse B12 deficiency with something else. Common symptoms include:

  • Tingling or numbness in hands, feet, legs, etc.
  • Fatigue (this was my main symptom)
  • Paranoia
  • Weakness
  • Difficulty walking
  • Swollen tongue
  • Cognitive difficulties (such as memory loss or difficulty reasoning
  • Hallucinations
  • Anemia
  • And more


As you can see, with symptoms like these it’s very easy to confuse B12 deficiency with something else. That’s why it’s important to see your doctor if any of these symptoms occur.

Early detection and treatment is important. “If left untreated, the deficiency can cause severe neurological problems and blood diseases,” says Dr. Bruce Bistrian, chief of clinical nutrition at Harvard-affiliated Beth Israel Deaconess Medical Center. There are many things you can do, starting with a physical including a blood test. A blood test is needed to properly test B12 levels. Specifically you will want to ask your doctor about your B12 levels if you are over 50, take a proton-pump inhibitor (such as Nexium or Prevacid) or H2 blocker (such as Pepcid or Zantac), you are a strict vegetarian, if you have had a weight reduction surgery, etc.

I can tell you, I am glad my doctor looked for it. Since I started the B12 shots, I do feel better. Less fatigued. I have not yet returned to running (a back issue now) and stopped the kickboxing (also due to back issue), but I do still walk and ride my bicycle. The B12 shots have made a noticeable difference.

To be clear – I am NOT a doctor. Please consult yours before taking B12 shots, etc. Be diligent about your health.

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