The Importance of Vitamin B12

One of my patients is a retired Marine. A few months ago he told me that he had been suffering from pains in his legs and feet for a couple of years. His doctor had tried several different pain medicines, but none of them really did much so he quit them all and just put up with it. Then he started taking a B vitamin with a lot of B12 in it, and to his amazement, within 3 days his feet and legs stopped hurting. It’s been over 6 months and the pain hasn’t come back. He’s decided to continue the vitamin, just to make sure.

Vitamin B12 is a water-soluble B vitamin that helps your body make new red blood cells , helps your nerves work, and prevents certain kinds of anemia. A deficiency in Vitamin B12 can show up as fatigue, weakness, depression or pain in your feet or hands.

According to the National Institutes of Health (NIH), Vitamin B12 is found mostly in animal proteins, such as fish, meat, poultry, eggs, milk, and milk products. Most healthy adults get enough Vitamin B12 in their diet; those who don’t either don’t get much animal protein in their diet or aren’t able to absorb Vitamin B12 very well.
Strict vegetarians may not get enough animal protein in their diet to satisfy the recommendation of 1 to 2 mcg daily of Vitamin B12. Others become deficient because they cannot absorb it very well, like the elderly, those who have had gastric bypass surgery and people who take certain medicines.

The most common cause of Vitamin B12 deficiency is not being able to absorb it. This can be due to a condition called atrophic gastritis, which affects 10-30% of the elderly. Atrophic gastritis interferes with the ability to absorb Vitamin B12 from your food because it decreases secretion of digestive juices such as gastric acid.
Our bodies only absorb about half the Vitamin B12 we get in our diet, which is usually attached to animal based protein like ground beef or chicken. Without enough stomach acid, your body can’t break down proteins and Vitamin B12 stays stuck to the protein.

Those who don’t absorb Vitamin B12 well may notice benefit from higher amounts of supplementation.
Medicines that can contribute to poor absorption and deficiency of Vitamin B12 include acid-reducing medicines such as Prilosec® (also known as omeprazole), Prevacid® (also known as lansoprazole), Protonix® or Nexium®. Older acid-blocking medicines which also impair absorption of Vitamin B12 include Zantac® (ranitidine), Pepcid® or Axid®. Metformin, a common pill for diabetes can also interfere with absorption of Vitamin B12.
Vitamin B12 contains cobalt and is available in several forms. The Vitamin B12 that is given as a shot is cyanocobalamin. Oral supplements are available as either cyanocobalamin, or methylcobalamin, and can be purchased without a prescription.

Most people who can absorb Vitamin B12 well only require 1 or 2 mcg daily. If you are over 70, take medicine for heartburn or an ulcer or have had gastric bypass surgery, you may need more than that. 1000-2000mcg daily of Vitamin B12 as an oral or a sublingual tablet can overcome poor absorption. Be sure to avoid the timed-release or long-acting products, because they may not be as well absorbed as the immediate release forms.
Since Vitamin B12 isn’t found in plant foods, if you are vegetarian the National Institutes of Heath suggests fortified breakfast cereals as an alternative source.

Vitamin B12 deficiency can be detected with a blood test. There are several ways to get more of the vitamin: monthly injections from your medical provider, tablets that you swallow and tablets that dissolve under your tongue. Your doctor or medical provider can advise you which would be best for you to take, and how much. There’s more information about Vitamin B12 at

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