Pernicious Anemia vs B12 Deficiency

A doctor explains about the link between pernicious anemia and vitamin b12 deficiency


Anemia is a blood disease when the hemoglobin is low and the body has very few red blood cells. Hemoglobin is an iron-protein compound found in red blood cells which is responsible for transporting oxygen. Pernicious anemia is a rare chronic form of anemia where there are too few red blood cells because of vitamin B12 deficiency. Vitamin B12 is important in the formation of red blood cells, neurological functions, and DNA synthesis. Pernicious means dangerous or deadly which was adopted as the name of the disease many years ago when there was no effective treatment for it and this disease was inevitably fatal. Nowadays, pernicious anemia can be treated when diagnosed properly even before other complications arise from the condition.

The primary sources of vitamin B12 are fish, meat, eggs, milk and dairy products. Vitamin B12 from dietary sources are absorbed through the intestinal cells after it combines with the gastric intrinsic factor. Pernicious anemia is usually caused by the lack of intrinsic factor, a gastric protein that is needed by the body in order to absorb vitamin B12. The cells lining an area of the stomach need to produce intrinsic factor which helps the small intestine absorb vitamin B12. Other causes may be due to inherited genetic factors and antibodies that attack the healthy tissues in the body, in the case of pernicious anemia, the antibodies attack the cells producing the intrinsic factor. This is the reason why it is believed that pernicious anemia is an autoimmune disease.

Pernicious anemia and B12 deficiency are different conditions. Pernicious anemia is the most common cause of deficiency in vitamin B12 but there are still other reasons for lacking vitamin B12 in the body. Not all individuals who have B12 deficiency develop pernicious anemia. There are a lot of other causes for the lack of vitamin B12.

Causes of B12 Deficiency

There are several ways for an individual to become deficient in vitamin B12:

Not enough intake of Vitamin B12 rich foods

Individuals who don’t eat enough meat, fish, and eggs don’t get enough source of vitamin B12. They are at risk of having vitamin B12 deficiency. Vegetarians are usually at risk of having vitamin B12 deficiency. Individuals who don’t eat meat but eat fish, dairy products, and seaweed are at a lower risk of becoming vitamin B12 deficient.

Gastric Atrophy

Gastric atrophy is caused by the chronic inflammation of the lining of the stomach which makes it difficult to produce, Intrinsic Factor, pepsin, or hydrochloric acid. Intrinsic Factor is essential in extracting vitamin B12 from food. Pepsin helps in speeding up the break-up of food. Hydrochloric acid is needed by the body to break down food. Atrophic gastritis is usually brought about by aging. It can also be caused by autoimmune gastritis wherein an individual produces antibodies that impair either the Intrinsic Factor and/or the parietal cells. The individuals who produce antibodies that destroy the Intrinsic Factor are diagnosed with pernicious anemia.

Gastric Bypass Surgery

Gastric bypass surgery is a surgical procedure wherein the stomach is divided into a small upper section and a larger bottom section and the small intestine is rearranged to connect both pouches. This procedure is done by individuals who want to lose weight by changing the way the stomach and the small intestine handle food. It makes the stomach become smaller and it makes the person feel full with less food.

Gastric bypass surgery limits the absorption of vitamin B12 and other nutrients needed by the body to function well such as iron and calcium. This is why individuals who undergo this procedure tend to have nutritional deficiencies that lead to other health conditions.


An ileostomy is a surgical procedure wherein the surgeon removes the colon or large intestine and sometimes the rectum. The surgeon cuts the end of the ileum or small intestine and brings it to the surface of the abdomen or skin to form a stoma or surgical opening.

This procedure is done to either treat or prevents further widespread of certain diseases such as:

  • Crohn’s disease
  • Ulcerative colitis
  • Familial adenomatous polyposis (FAP)
  • Colonic Hirschsprung’s disease
  • Ovarian cancer or colorectal cancer


Certain drugs affect an individual’s absorption of vitamin B12. These are:

  • Ibuprofen as painkiller
  • Lansoprazole and omeprazole as proton pump inhibitors for individuals with gastric problems
  • Metformin for people with type 2 diabetes
  • Contraceptive pills
  • Cimetidine to treat peptic ulcers
  • Colchicine to treat gout
  • Topiramate, Primidone, Pregabalin, and Phenobarbital for epilepsy

Most of these drugs have a minimal impact on B12 levels except for the proton pump inhibitors and any deficiency brought about by these drugs can be corrected by taking vitamin B12 supplements.


There are certain parasites that affect an individual’s B12 levels. These include:

  • Beaver Fever – a parasite that lives in stagnant water
  • Diphyllobothrium or fish tapeworm lives in the stomach and steals up to 80% of an individual’s B12

Nitrous Oxide or laughing gas

This compound is used in dental surgery and now is used as a recreational drug in the UK. This compound affects an individual’s B12 levels.