Does Vitamin B-12 Cause Diarrhea?

Diarrhea is the result of your body eliminating stool before the large intestine can properly absorb water back into your body, which causes the stool to be runny and watery. Diarrhea is a symptom of several conditions that relate to a deficiency of vitamin B-12. Often though the condition that causes the deficiency also causes the diarrhea, but occasionally the diarrhea is a direct result of a vitamin B-12 deficiency. Vitamin B-12 is present in foods such as cheese, milk and eggs.

A lack of vitamin B-12 causes anemia because your body lacks sufficient amounts that you need to produce red blood cells. Anemia is a condition in which your body lacks red blood cells. These cells carry oxygen through your bloodstream to every part of your body. Not having enough red blood cells to bring oxygen to your cells makes you tired and causes other symptoms, such as diarrhea, pale skin, bleeding gums, a sore tongue and weakness.

Crohn's disease is one of two major inflammatory bowel diseases, along with ulcerative colitis. Inflammatory bowel diseases impact your ability to digest food, which might affect your ability to absorb vitamin B-12. A difficulty absorbing vitamin B-12 is usually the cause of a vitamin deficiency. Crohn's disease causes inflammation of your digestive tract, which runs from your mouth to your anus. It may also cause skin problems, arthritis, fever, rectal bleeding and abdominal pain. A vitamin B-12 deficiency does not actually cause diarrhea in Crohn's disease, but a resulting deficiency from Crohn's may lead to more diarrhea as you become vitamin B-12 anemic.

Ulcerative colitis is the other main inflammatory bowel disease. Diarrhea is one of the main symptoms of ulcerative colitis. The lining of the large intestine becomes inflamed if you have ulcerative colitis, causing ulcers in the top layer of the lining of the large intestine. This includes the colon and the rectum. The ulcers and inflammation cause the same basic symptoms and signs as Crohn's disease, though the specific cause of diarrhea is inflammation in the colon leading to frequent emptying of the bowels. Since ulcerative colitis interferes with the way your body digests food, it can also cause a vitamin B-12 deficiency.

Sprue is another condition that interferes with the absorption of nutrients, which might lead to a vitamin B-12 deficiency and anemia. Symptoms of sprue include diarrhea, loss of appetite, weight loss, muscle cramps and bone pain. Tropical sprue and nontropical sprue are two types of the disorder. A bacterial or viral infection of the intestinal lining may cause tropical sprue, though poor nutrition is another possibility. Antibiotics and vitamin supplements treat tropical sprue. Nontropical sprue, or celiac disease, only produces symptoms when someone with the disease eats gluten, which is a form of protein in barely, wheat and rye. If you have nontropical sprue, you must avoid all foods containing gluten to eliminate diarrhea and allow your body to absorb vitamin B-12 properly.