Vitamin B12 deficiency can cause peripheral neuropathy among a number of different diseases.


Vitamin B12 is absolutely essential for the normal function of every cell in the brain and nervous system. Damage to the nervous system caused by B12 deficiency can actually be permanent and irreversible.

Like so many other vital nutrients, vitamin B12 is also essential for energy production and cellular repair.

Vitamin B12 helps the body make healthy red blood cells and helps keep nerve cells healthy. 


The parietal cells of the stomach produce Intrinsic factor (IF), also known as gastric intrinsic factor(GIF). Normal absorption of B12 requires intrinsic factor. All pathways known to stimulate gastric acid secretion also stimulate secretion of intrinsic factor. So if you are taking an acid blocking medication, you may be low on B12. Too little vitamin B12 in the body causes one form of vitamin B12 deficiency anemia called pernicious anemia.  

Deficiency of vitamin B12 is also one of the more common deficiencies seen in private practice. Blood tests often show that many adults have inadequate B12 levels.

Low B12 levels can be due to a combination of diet and a number of different factors. Normal aging is one of these factors.  B12 deficiency can be more common in adults over 50 because as we age our stomach may make less digestive acid. 

Diets low in animal source protein can cause B12 deficiency. Meat, fish, eggs, milk, and other dairy products contain high levels of B12. It is very difficult to get B12 from vegetable sources. 

Some other factors include chronic use of medications that affect the lining of the GI tract like NSAIDS. Bowel diseases like celiac, irritable bowel and Chron’s can affect B12 absorption.  and, Many prescription medications also can interfere with absorbing B12.

One of the most common reasons for vitamin B12 deficiency in diabetics is the prescription drug metformin.


Signs and symptoms of low B12 levels are very common, and are often passed on as simple fatigue or aging. These symptoms include low energy, fatigue, depression, and memory changes. (And can be one cause of peripheral neuropathy.) B12 deficiency in the outpatient setting is probably second only to vitamin D deficiency.


Since the effects of vitamin B12 deficiency can be permanent, is very important that you and your doctors take this nutrient and its deficiency very seriously. This is especially true if you suffer from neuropathy or any neurologic disorder.

Like all the key nutrients, it is most important to clearly identify, then attempt to correct a vitamin B12 deficiency. B12 levels are checked by blood tests.

Eliminating correctable underlying causes such as poor dietary habits and unnecessary drug use can be some of the easiest fixes.

High dosages of oral B12 supplementation under supervision and/or injection of vitamin B12 may be necessary to correct low levels and frank deficiencies.

So don’t be afraid to ask questions.

All adults should routinely have vitamin B12, vitamin D, and folic acid levels checked at every annual physical examination, and more often once supplementation has begun.

However, it is important that you do not just go out and start taking high doses of B12 all by itself. High doses of any one of the B vitamins without supplementing the others, can lead to deficiency symptoms of the other B vitamins. And, deficiency of any of the B’s actually can lead to neuropathy or neuropathy-like symptoms. So, it is wise to get the blood tests first to see if taking extra B12 may help you.