Too Much Vitamin B12 Can be Harmful - My Bariatric Life

by Cheryl Ann Borne Patient Advocate

Vitamin B12, in combination with other B vitamins, plays an important role in physical well-being. Vit B12 maintains a healthy nervous system, helps to maintain energy levels, and is essential for DNA synthesis.

Vit B12 is critical for the metabolism of cells, particularly in the digestive tract and bone marrow. They are important in the formation of red blood cells, platelets and immune cells. They also prevent accumulation of homocysteine, a toxic metabolic byproduct linked to cardiovascular disease and connective tissue abnormalities.

Weight Loss Surgery and Vit. B12 Deficiency

Gastric bypass surgery decreases the size of the stomach by bypassing part of the small intestine. The surface area for the digestion and absorption of the nutrients in food is also diminished. Weight loss surgery promotes a loss of the cells that secrete stomach acids and intrinsic factor for digestion. Intrinsic factor is a protein the body needs to absorb vitamin B12.

Vit B12 and the Bariatric Patient

Vitamin B12 is no longer absorbed easily after gastric bypass, so eating foods that contain vit B12 and taking supplements is recommended.

Foods that contain vitamin B12 are red meat, eggs, dairy and fish. Vegetables do not contain vit B12. Clams and beef liver are the foods with the most vit B12. Salmon, trout and beef are moderate sources.

Because the part of the intestine that absorbs vit B12 has been removed or bypassed in the bariatric patient, an oral vit B12 supplement is ineffective. Instead, a sublingual (under the tongue) vit B12 supplement either in tablet or liquid form should be taken daily. A prescription vit B12 nasal spray that can readily be absorbed into the bloodstream is also available.

Symptoms and Effects of Vitamin B12 Deficiency

A deficiency of vitamin B12 can cause vitamin B12 deficiency anemia. A mild deficiency will have minimal symptoms or no symptoms. More advanced anemia will cause symptoms such as weakness, rapid heart rate and breathing, pale skin, sore tongue, easy bruising, and diarrhea or constipation.

If the deficiency is not addressed, it can damage nerve cells and produce tingling or numbness in the fingers and toes, difficulty walking, changes in mood, and disorientation.

Another and less talked about problem would be the ill effects of a surplus of vit B12.

Symptoms and Effects of Vitamin B12 Saturation

After my gastric bypass surgery, I was advised by my doctor to take a vit B12 bilingual supplement. I did this accordingly as well as follow-up testing. A recent testing revealed that my B12 levels were low and it was recommended that I double my daily intake of B12. Having done this, my most recent testing showed that my B12 levels were ridiculously high. The normal range is from 200-1100 and my level was above 2000. I was surprised when my doctor informed me that saturated B12 levels can lead to leukemia over time.

Dangers of Vit B12 Overdose

Very little is known about vit B12 overdose. The vitamin is considered relatively safe so there has been little research done to explore what happens in the case of an overdose. Some studies are showing possible links to leukemia, prostate cancer, and stomach cancer.

Contributing to the grey area of information, the Institute of Medicine of the National Academies does not specify the maximum daily amount of vit B12 that could pose a health threat although it does warn against overdose because of the potential for adverse side effects.

Reported side effects include pulmonary edema or the accumulation of fluid in the lungs and congestive heart failure.

At this point, much speculation about what happens with B12 toxicity remains although the results at present raise concerns.

Gastric Bypass Issues - accessed 6/20/12 - accessed 6/20/12
Natural Living Natural Healing - accessed 6/21/12
WebMD - accessed 6/21/12

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Cheryl Ann Borne
Meet Our Writer
Cheryl Ann Borne

Cheryl Ann Borne, writing as My Bariatric Life, is a contributing writer and Paleo recipe developer. Cheryl is an award-winning healthcare communications professional and obesity health advocate who has overcome super obesity and it’s related diseases. She publishes the website, and microblogs on Facebook, Twitter, and Pinterest. Cheryl is also writing her first book and working on a second website.