Gastric Bypass Surgery and Vitamin B12 Deficiency

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People who undergo gastric bypass surgery are likely to develop a vitamin B12 deficiency.  Vitamin B12 is absorbed in the stomach.  When surgeons cut off a part of the stomach, they prevent the release of enzymes necessary for the absorption of vitamin B12.

Vitamin B12 is produced in the guts of animals, and is found in meat, chicken, eggs and dairy products.  This vitamin is bound to the protein of the food we eat.  Pepsin – an enzyme in our stomach – removes the vitamin B12 from the protein.  Intrinsic factor is a protein that binds to the B12 and brings it to a section of the intestine called the ileum.  The ileum has receptor cells that absorb the vitamin B12 and pass it along to the bloodstream.

The stomach produces hydrochloric acid.  The enzyme pepsin works only in the presence of hydrochloric acid.  When part of the stomach has been removed or sectioned off, cells that secrete intrinsic factor (which binds to the B12) and hydrochloric acid are destroyed.  Therefore, none of the chemical reactions needed to obtain vitamin B12 can take place.

Vitamin B12 is necessary for proper nerve growth and red blood cell formation.  Signs of a vitamin B12 deficiency include dizziness, memory loss, depression, tingling of the hands and feet, loss of bladder control, fatigue, weakness and constipation.

A vitamin B12 deficiency that is left untreated can lead to paralysis, internal bleeding and death.

It is imperative that anyone who undergoes gastric bypass surgery should discuss with his/her doctor how to obtain vitamin B12 through injections or supplements.