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Vitamin B12

Vitamin B12 is one of the most important vitamins in our body. It helps in the repair of DNA in every cell of the body and is important in maintaining the integrity of our genome. * 

It is particularly important for the health of the brain, nerves, blood cells, fatty acids metabolism, gastrointestinal tract and heart.*  


What are the effects of low Vitamin B12?  

Low vitamin B 12 can cause:  

1. Lack of energy . 

2. Tingling and numbness in the feet and hands due to peripheral neuropathy. 

3. Memory loss. 

4. Dementia .

5. Depression.

6. Abnormal gait and lack of balance. 

7. Anemia

8. Burning of the tongue, poor appetite. 

9. Constipation alternating with diarrhea, vague abdominal pain.  

10. Increase in the level of Homocysteine which is a risk factor for heart disease. Low folic acid is the other contributory factor for raising Homocysteine level. 


Who is at risk for low Vitamin B12?    

1. Anyone on a strict vegetarian diet, because vegetables are devoid of Vitamin B12.  

2. Anyone on Metformin (Glucophage).  

3. Anyone on stomach medicines such as Prilosec, Prevacid, Protonix, Aciphex, Pepcid, Zantac, Tagamet etc.  

4. Antibiotics can lower Vitamin B12 by interfering with the normal intestinal bacterial flora.

5. Anyone who has undergone stomach surgery including various forms of bariatric surgery for weight loss.  

6. Gastrointestinal disorders such as chronic pancreatitis, atrophic gastritis, small intestinal resection or bypass, gluten enteropathy, Crohn's disease and malignancy.  


How do I know if I'm low in Vitamin B12?  

Vitamin B12 deficiency often remains undiagnosed because physicians generally don't think of it as a possibility. 

For example, when a diabetic patient complains of tingling in their feet, physicians do all the work-up to diagnose diabetic peripheral neuropathy. They then start you on drug treatment without checking your Vitamin B12 level, even if you are on metformin. In reality, peripheral neuropathy in diabetic patients on metformin is often due to two factors: diabetes itself and vitamin B12 deficiency. 

Vitamin B 12 deficiency can be diagnosed by a blood test.  

A blood level less than 400 pg/ml indicates Vitamin B12 deficiency. In my clinical experience, patients do much better when their Vitamin B12 level is close to 1000 pg/ml.  


What are natural sources of Vitamin B12? 

Animal products are the main natural sources of Vitamin B12.  

Plant derived food is devoid of Vitamin B12.  

Good dietary sources include egg yolk, salmon, crabs, oysters, clams, sardines, liver, brain and kidney.  

Smaller amounts of Vitamin B12 are also found in beef, lamb, chicken, pork, milk and cheese.    


Is there danger of Vitamin B12 Overdose?  

To my knowledge, there are no reported cases of Vitamin B12 overdose in medical literature.  

Vitamin B12 in high doses along with folic acid and Vitamin B6 helps to lower homocysteine level.  

High level of homocysteine is a known risk factor for cardiovascular disease. Lowering of homocysteine level helps to lower cardiovascular risk.   


What are the different forms of Vitamin B12 supplements?  

Vitamin B12 supplements are available as oral pills and pills for sublingual absorption. 

I prefer the sublingual absorption route because the absorption of vitamin B12 from the oral cavity (dissolving in the mouth) is excellent, better than from the stomach and intestines.  

Vitamin B12 is also available in the form of an injection. You need a prescription from a physician for a vitamin B12 injection.  



Warnings – Disclaimer: This website is for educational purposes only. The information as well dietary supplements in this website are not intended to diagnose, treat, cure or prevent any disease. *These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are Not intended for use by pregnant or nursing women. If you are taking any medications, planning any medical or surgical procedure or have any medical condition, consult your doctor before using any of the supplements. Discontinue use and consult your doctor if any adverse reactions occur. Keep out of reach of children. Do not use if outer wrap is missing or torn. Store at room temperature.  


This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, photoEndocrinology and Metabolism.

Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.




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