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What Causes Vitamin B12 Deficiency

Kanika Khara Jul 31, 2020
Vitamin B12 is essential for the production of red blood cells in the body, and its deficiency can lead to severe health problems like anemia, permanent nervous system disorders, etc. This story will discuss some of the symptoms and causes of vitamin B12 deficiency.
Cobalamin, which is another term for vitamin B12, is a type of vitamin B, and it is a complex structure that plays an important role in the proper functioning of the brain and nervous system. It acts as a co-factor in the conversion of methylmalonic acid into succinyl-CoA, and conversion of homocysteine into methionine along with folic acid.
It also plays a key role in repairing the damaged body cells and synthesizing essential DNA (deoxyribonucleic acid) molecules. It helps stimulate the mechanisms required for detoxification of the body by removing poisonous chemical substances like lead, arsenic, and antimony. A drop in the levels of this vital nutrient in a person's body may cause many health problems as discussed below.


In adults, the effects of a deficiency of vitamin B12 become visible only after a few months, as their bodies have extensive reserves of it that can be used, whereas in infants and children, the symptoms become apparent quite early.
Some of the commonly observed symptoms are as follows:
  • Rapid and short breathing
  • Weak pulse rate and abnormal heartbeats
  • Frequent headaches, weakness, tiredness, and lightheadedness
  • Soreness of tongue, mouth, and throat
  • Bleeding gums
  • Loss of appetite and weight
  • Diarrhea and constipation
  • Numbness or tingling in the fingers and toes
  • Depression
  • Dementia


Other than aging and absence of foods rich in vitamin B12 (like meat, animal products, fish, eggs, and dairy products) in the diet, there are some possible medical causes for its deficiency, which are as follows:
  • Blind Loop Syndrome: It is a rare intestinal defect that mainly occurs due to bacterial overgrowth and malabsorption of essential nutrients. It develops as a small loop in the intestines that allows the digesting material to enter but not exit.
  • Crohn's Disease: It is an inflammatory disease of the digestive system that affects any region of the gastrointestinal tract from the anus to the mouth, leading to abdominal pain, diarrhea, vomiting, weight loss, etc.
  • Diphyllobothrium Latum: It is a human intestinal infection that occurs due to frequent consumption of raw or pickled fish. The symptoms observed are diarrhea, abdominal pain, vomiting, weight loss, fatigue, constipation, etc.
  • Pernicious Anemia: It is a chronic progressive anemia which occurs due to poor intestinal absorption of cobalamin, due to the defective production of intrinsic factor (a glycoprotein, essential for the absorption of this vitamin) by the gastric mucosa.
  • Vegetarianism: It is a dietary practice of totally avoiding meat products in a regular diet and consuming only vegetables, grains, and nuts. Plants are not a good source of vitamin B12; hence, strictly following this diet can cause a deficiency of this vitamin in the body.
Atrophic Gastritis: It is a chronic inflammation of the stomach mucosa that causes loss of gastric glandular cells, which are ultimately replaced by intestinal and fibrous tissues.
Due to this, the stomach's secretion of essential substances like hydrochloric acid, pepsin, and intrinsic factor is diminished. It causes digestive problems, vitamin B12 deficiency, and megaloblastic anemia.
Deficiency of this vitamin can also result from certain medications like metformin or inherited conditions like transcobalamin deficiency. This deficiency can be prevented by including animal products like milk, cheese, and eggs in the diet. People who follow a vegan diet can avoid this condition by daily consuming a vitamin pill or food products that are rich in vitamin B12.
Disclaimer: This story is for informative purposes only and should not be used as a replacement for expert medical advice.