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  • Writer's pictureMiriam Diaz-Gilbert

Living and Running with Painful B12 Deficiency

Updated: Nov 2, 2023

It’s been over 11 years since my diagnosis. This is what I’ve learned, and what you and doctors need to know.

Photo by Jon Gilbert

Research by NIH (National Health Institute) suggests that between 1.5% — 15% of the population suffers from vitamin B12 deficiency. I am included in this statistic.

In this piece I share what I have learned about B12 deficiency since my diagnosis. I have learned more about the causes of B12 deficiency, its symptoms, treatment for B12 deficiency, and medications that are known to deplete the body of vitamin B12.

Causes of Vitamin B12 Deficiency

Vitamin B12 is essential to maintain a healthy brain and nervous system and to produce myelin sheath around our nerves. Several conditions can cause B12 deficiency. These include, but are not limited to, Celiac disease, pernicious anemia, heavy drinking, immune systems disorders, and some medications. Vegetarians are more prone to develop B12 deficiency.

Painful and Debilitating Symptoms

Before being properly diagnosed in 2009, I suffered for almost two years. I began experiencing painful twitching in my fingers and hands. Then I began experiencing painful twitches and spasms in my legs. Soon the toes in my feet began to twitch, cramp, and spasm. My right toe became numb. I’d wake up screaming in the middle of the night to sudden excruciating spasms in my right calf and painful curling of my right toe. I had tingling sensations in my limbs. I felt pins and needles sensations.

My quality of life was affected. My primary care doctor referred me to a neurologist at a local teaching hospital. She conducted an EEG (electroencephalogram) test and an EMG (electromyography) test and announced I did not have ALS, and that my symptoms would resolve themselves.

My symptoms did not resolve themselves. Things got progressively worse.

The numbness, twitching, spasms, and tingling sensations got more intense. The burning and numbing sensation in both feet and toes made shoes uncomfortable to wear. I’m a runner. I run ultramarathons — 50 mile and 100 mile distances, and 24 hour running events. My mind was ready to run but my legs were fatigued and couldn’t propel themselves forward. It was taking me longer to run distances in the time I was accustomed.

My legs experienced muscle weakness, tingling, and electrical shock like sensations. I had difficulty going up stairs. I felt short of breath. For the first time ever I experienced shortness of breath during an ultra.

I felt short of breath at the 2008 Laurel Highlands 70 mile trail ultra. I missed the 19.3 mile cutoff. This was my 5th ultra and my first DNF (did not finish). I endured more pronounced painful twitching, spasms, tingling, pins and needles sensations, and numbness in my hands, fingers, and right leg, toe, and calf. The painful numbness, calf spasms, and right toe curling made it difficult for me to get a good night’s sleep. I was fatigued. My toes burned in my shoes.

Tests and More Tests

I saw two more neurologists in the same teaching hospital. I got another EEG and EMG. Both were normal. I got a spinal tap. It revealed abnormally high levels of protein in my spinal fluid.

MS was ruled out. Forty-eight vials of blood were drawn in a period of four weeks testing for everything under the sun. I got an MRI and CT Scan, this time to test for bone marrow cancer.


One neurologist said I had CIDP (chronic inflammatory demyelinating polyneuropathy) and scheduled me for plasmapheresis but then cancelled it. I was misdiagnosed. But I was told I was a little low in B12 and to go to my primary doctor for a B12 injection. I got the injection.

My symptoms and suffering continued. The same neurologist told me she could not figure out what was wrong with me. She told me my symptoms were similar to those experienced by workers at a pork processing plant and to stop eating pork for now. How odd — I did not work at a pork processing plant and I was never asked if I eat pork.

Unable to Walk and to Run Normally

My fingers continued to painfully lock, fan out and become stiff anytime, anywhere — while teaching, eating, driving, watching TV, and when struggling to run. My gait, walking, and running were affected. I was no longer a fast walker. I could no longer push myself when I ran. I was dragging my feet.

My right toe and right calf suffered the most, especially at night. I was unable to sleep.

My legs experienced muscle weakness, tingling, pins and needles, and electrical shock like sensations. I continued to have difficulty going up stairs. My painful and debilitating symptoms were intolerable.

What was causing the numbness, twitching, and tingling on both legs, feet, and arms? Why did I experience terribly painful spasms in my right toe, which was now completely numb? Why did I have elevated levels of protein in my spinal fluid? Was it CIDP or not? Why couldn’t I walk normally? Why couldn’t I run? I needed answers.

In Search of Answers

Not satisfied with the so-called “pork diagnosis,” I did my research. I found a renowned neurologist and CIDP specialist at Johns Hopkins. I made an appointment. I got copies of all doctors’ clinical notes along with test results that showed my B12 level was 211 and my MMA (methymalonic acid) was 415. Low B12 and high MMA is not a good thing.

He reviewed my records, tests, and my symptoms. During my appointment, he did an assessment of my numb right toe, which did not respond to pin pricks. I got one more EMG test during my visit. It was normal.

And then, right then and there, I got my diagnosis — myelopathy of the spinal cord due to severe B12 deficiency. I discovered my body is not able produce enough B12 naturally to make myelin sheath around my spinal cord. I can’t absorb B12 from the foods I eat. I am not a vegetarian.

My severe B12 deficiency is neurological.

I was given a 1000 mcg B12 injection. I went home with a prescription for a B12 injection every day for a week, then once a week, and then once a month for life, along with daily oral 1000 mcg B12. The day was September 24, 2009.

With my B12 shots and sublingual 1000 mcg B12 tablets my B12 level of 211 continued to rise, and my MMA level of 415 continued to decrease. A few months later, my B12 level was 2000 and my MMA level was 141. This was great! The B12 level always needs to be higher than the MMA level. The reverse is not good.

I Could Still Do the Distance

A month after my diagnosis, I went for a 3 mile run. It felt great. Slowly, I began to add more miles. I trained for the June 2010 North Face 50 mile trail ultra in Virginia, my fifth 50-mile ultra at the time. I needed to know I could still do the distance. I didn’t make the 13-hour time limit. At 12:54, I had 4.1 miles to the finish. I kept going. At the finish, my family, the race director, and a volunteer greeted me with a finisher’s medal. I placed 183/203 runners but without an official time. I did the distance in my unofficial time of 14:25:51. I was thrilled!

With proper treatment consisting of B12 injections and sublingual oral tablets, I have gone on to finish 15 more ultramarathons since my diagnosis in 2009. I have even placed second and third overall, and in my age group.

Vitamin B12 For Life

I am on vitamin B12 injections for life. Once a year, I renew my yearly prescription for vials of B12 and syringes. Because I’m always training for ultras — I run 2–3 a year — my B12 injections were increased to once a week. I inject myself. I also take daily 1000 mcg sublingual B12 tablets which I purchase over-the-counter.

With my weekly B12 injection. Photo by Jon Gilbert.

B12 Deficiency is Serious and Dangerous

Had I not gotten a third opinion, my situation could have potentially gotten worse.

Untreated B12 deficiency is potentially life threatening. It can lead to paralysis, dementia, psychosis, and permanent and irreversible damage. My right toe has residual numbness and nerve damage.

Based on my experience, if you are having tingling, numbness, and spasms in your limbs, and get awaken by painful calf and toe cramps in the middle of the night or while stretching in bed before getting up in the morning, make an appointment to see your doctor and get your B12 and MMA levels tested at the same time. If these symptoms persist, see a top neurologist. Get a second and third opinion. Learn about B12 deficiency causes, symptoms, and treatment.

My Story Gives People Hope

I have learned a lot about B12 deficiency, how it diminishes quality of life, and how to get treatment and have a productive and active life. Seven years after my diagnosis, I wrote a piece for Huffington Post about my painful B12 deficiency and how I got my running legs back. I did not want others to suffer the symptoms I endured. I never imagined the response this piece would receive. Folks from Nepal, India, Lebanon, Iran, Qatar, Canada, and the states wrote to me in desperation and in search of answers.

My second article - The Dangers of B12 Deficiency Poses for Athletes - is published in Women's Running magazine

I continue to receive emails on my website, messages on my FB page, and YouTube channel and DMs on Twitter from people all over the world who reach out to me after reading my story on Huffington Post and my website blog.

They share their symptoms with me —tingling, numbness, twitching, gait imbalance, spasms, pins and needles sensations, and tight calves.They tell me their doctors can’t figure out their symptoms. They tell me my story inspires them and it gives them hope.

“Your story in the Huffington Post about how you went about solving your B12 deficiency was inspiring.”

“I just read your article on B12 deficiency in Women’s Running and I think your article might be the answer I am searching for, or a least a step in the right direction.”

“I just came across your blog when I was searching the subject of B12 deficiency. Your articles gives me hope. Very inspirational.”

They also ask me questions — especially, how long did it take you to feel better after you started B12 shots? What should my B12 level be?

Every person is different. The cause of B12 deficiency varies from person to person.

Not all B12 levels are the same. Different labs have different ranges. Normal levels range from 232–1245 in one lab and 200–1100 in another lab.

With proper treatment, some people diagnosed with B12 deficiency may find relief sooner than others. Some may require only oral B12 tablets, other injections only, and some, like me, will require both. One of my readers shared that he is prescribed B12 nasal spray.

What I’ve Learned About Living With and Treating B12 Deficiency

I tell my readers I’m not a doctor but I’m happy to help in any way I can. I share what I’ve learned about living and running grueling distances with B12 deficiency that needs to be treated lifelong.

I share with them what I’ve learned about B12 deficiency symptoms and treatment, how to talk to your doctor, and medications that deplete the body of vitamin B12.

I’ve experienced B12 depletion with one medication and my husband has experienced depletion with another.

Proton-pump Inhibitors

I didn’t know it at the time, but the first sign of this depletion was my toes suffering a painful burning sensation that slowed me down during the 2017 Wildcat 100 mile ultra. Every 20 miles or so I had to immerse my feet in an ice bath just to get some relief from the numb and burning sensation in my toes. I ran/walked the last 10 miles in my Birkenstocks so my burning toes wouldn’t be confined and to give them relief on the run.

My fastest 100 miler is 27:13:07. Even though the time limit at the Wildcat 100 is 40 hours, I was very surprised that it took me so long — 37:32:07. I felt unusually fatigued and wiped for over two weeks after the race. I started to experience twitching in my legs and hands. I had excruciating spasms in both calves and curling in both big toes.

Symptoms were resurfacing 8 years after my initial diagnosis. I went to see my doctor to test my B12 level and my MMA level. I couldn’t understand why this was happening. I asked myself, “What am I doing differently?”

And then it hit me — I’ve been taking Prilosec almost a year for GERD. I researched Prilosec and B12 deficiency and voila! In some patients, proton-pump inhibitors such as Prilosec, Nexium, and others are known to deplete the body of vitamin B12.

I got my B12 level tested. The results showed my B12 level was 1226. This is normal for many people. In my case, my neurologist says my level needs to be over 2000. I stopped taking Prilosec. I continued weekly B12 shots and increased my sublingual tablets from 1000 mcg to 2000 mcg daily. Within a couple of weeks I started to feel better.

Follow up B12 and MMA tests a month later showed my B12 level was back up in the 2000 range and I was feeling good again. Instead of taking Prilosec for my reflux, I started brewing ginger root. Ginger root is good for reflux and inflammation, and it doesn’t deplete my body of B12.

Prilosec, a proton-pump inhibitor, prescribed to help with GERD (gastroesophageal reflex disease) depleted my body of B12. This depletion explained my slow performance at Wildcat 100.

Chemotherapy-induced Peripheral Neuropathy

After my husband began aggressive radiation and chemo for his stage IV cancer, he complained of tingling and numbness in his toes. I wondered if the radiation and chemo was depleting his body of B12.

I told the oncologist to test my husband’s B12 and MMA levels. The oncologist thought that was an odd request. I had to educate him about B12 deficiency. The reality is that most doctors are not aware of B12 deficiency and its causes, medication-induced B12 deficiency, and how to treat B12 deficiency.

And just as I thought, my husband’s B12 level was very low. It was 190. I had him take 3000 mcg B12 sublingual tablets daily. During his next bi-weekly chemo infusion, his B12 level was tested again and his level shot up from 190 to 561. Two weeks later his level was over 2000.

Now he takes daily 1000 mcg sublingual B12 tablets. Vitamin B12 can help reduce chemotherapy-induce peripheral neuropathy.

The Cost of Treating B12 Deficiency

During the last 11+ years, I’ve also learned quite a bit about the cost of treating B12 deficiency.

B12 deficiency is easily treatable. But depending on your health insurance, it can be very expensive even with insurance. However, if you educate yourself and inject yourself, you will save money, especially if you need B12 injections for life.

At one time I was paying $47/ injection to my primary doctor and injected in my thigh by a patient technician. Four shots a month was costing me $188 x 12 months =$2, 256/yr. This cost was not covered by our Aetna insurance even though untreated B12 deficiency is dangerous.

In search of less expensive B12 treatment, I discovered CVS Minute Clinic. Out-of-pocket, I paid $27/injection. A nurse practitioner injected my thigh. Then Aetna dropped our coverage through my husband’s employer. We got new health insurance we pay for.

To save money, I decided to inject myself. After all, I had been watching others inject me. It’s very simple. With our new health insurance, I now pay out-of-pocket $14.30 for 10 vials of vitamin B12 (10 injections) and $7.56 for 10 syringes for a total of $21.86 for 10 weeks or $2.18/injection.

My yearly out-of-pocket cost of my B12 injections is approximately $115/yr not including the over-the-counter sublingual B12 1000 mcg tablets which I buy on sale — buy one, get one free — at CVS.

Don’t Ignore B12 Deficiency Symptoms

Painful tingling, numbness, twitching, calf spasms, toe curling, burning toes, electrical shock sensations, pins and needles, and the inability to walk and to run normally were my symptoms.

If you have these or other symptoms associated with B12 deficiency, see your doctor. Demand that you get your B12 and MMA (methymalonic acid) levels tested at the same time. Get tested for pernicious anemia, too.

Be mindful of any medications you might be taking and see if they are known to deplete the body of B12. Talk to your doctor. If you are not satisfied with your doctor, seek a second and third opinion.

If you are diagnosed with B12 deficiency, whether it’s due to a vegetarian diet, a neurological cause, medications, illness or disease, the good news is that it is easily treatable.

If you are a runner and athlete and you’re experiencing these symptoms, see see your doctor.

I am glad I’m very physically active and still able to run ultra distances with permanent right toe nerve damage and numbness.

Despite being treated with B12 injections and tablets, I still have twitching, spasms and other symptoms that flare up from time to time. By the time I was properly diagnosed, I already had nerve injury.

If nerves are injured and only partly or even to a major extent recover, symptoms can come and go but should not get worse. It’s important to get a diagnosis early. Getting treatment early and keeping B12 levels high is essential. Follow-up levels are important and need to be part of your routine blood labs.

Doctors Need to Learn About B12 Deficiency and to Listen to Patients

I learned early on that not all doctors listen carefully to their patients. I endured unnecessary suffering and expensive tests that didn’t alleviate my painful and debilitating symptoms.

While they were ruling out ALS, MS, CIDP, and bone marrow cancer, my initial doctors forgot to rule out B12 deficiency. They tested my B12 and MMA levels only once and didn’t pay greater attention to the results.

As I reflect on my symptoms, the physical and emotional pain I endured, and the very expensive tests I underwent for almost two years with no diagnosis and no end to my pain and suffering, I wonder….

Had my initial doctors been trained in and knowledgeable about the symptoms, treatment, and dangers of untreated B12 deficiency, I would have been properly diagnosed sooner than later.

An article in Wall St. Journal points out that most doctors are not trained to look for B12 deficiency in their patients.

And as I learned from my experience, one B12 injection alone will not end the patient’s symptoms and suffering or treat B12 deficiency. Listen to your patients! Don’t let debilitating and dangerous B12 deficiency stop your patients in their tracks!


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You might also be interested in my memoir. Read excerpts from, praise for, and listen to podcast interviews about my memoir Come What May, I Want to Run: A Memoir of the Saving Grace of Ultrarunning in Overwhelming Times.


Tina Willis
Tina Willis
May 04, 2023

Did you get low potassium when you started B12? And how did you deal with that? How long did that last? I'm a runner with a B12 deficiency. My initial symptoms have improved a lot. But the low potassium (or low folate?) I think is happening daily, and really slowing my blood pressure and causing weird fatigue. Also -- my worst symptom, I think, was reflux and distended belly! So that might explain your reflux. I've read some sources saying B12 deficiency can cause reflux. But I'm still not really sure whether that's true. also, do you offer paid consults?

Miriam Diaz-Gilbert
Miriam Diaz-Gilbert
May 06, 2023
Replying to

Thanks for reaching out. I don't have low potassium. What did your doctor recommend for your low potassium? Have you been tested for B12 deficiency? What did your doctor prescribe? Have you seen a GI doctor for you reflux and distended stomach?

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