Weight loss (bariatric) surgery frequently leads to vitamin B12 deficiency, as surgery can result in the gut no longer producing intrinsic factor. Intrinsic factor (IF) is needed if the body is to absorb B12 successfully into the bloodstream.
There are many types of weight loss surgery that can result in chronic vitamin B12 deficiency:
Vertical Banded Gastroplasty (VBG)
VBG is a purely restrictive procedure. In this procedure the upper stomach near the esophagus is stapled vertically for about 2-1/2 inches (6 cm) to create a smaller stomach pouch. The outlet from the pouch is restricted by a band or ring that slows the emptying of the food and thus creates the feeling of fullness. The risk of vitamin B-12 deficiency is lower than in other procedures.
Biliopancreatic Diversion (BPD)
BPD removes approximately 3/4 of the stomach to produce both restriction of food intake and reduction of acid output. Leaving enough upper stomach is important to maintain proper nutrition. The small intestine is then divided with one end attached to the stomach pouch to create what is called an “alimentary limb.” All the food moves through this segment; however, not much is absorbed. The bile and pancreatic juices move through the “biliopancreatic limb,” which is connected to the side of the intestine close to the end. This supplies digestive juices in the section of the intestine now called the “common limb.” The surgeon is able to vary the length of the common limb to regulate the amount of absorption of protein, fat and fat-soluble vitamins.
Extended (Distal) Roux-en-Y Gastric Bypass (RYGBP-E )
RYGBP-E is an alternative means of achieving malabsorption by creating a stapled or divided small gastric pouch, leaving the remainder of stomach in place. A long limb of the small intestine is attached to the stomach to divert the bile and pancreatic juices. This procedure carries with it fewer operative risks by avoiding removal of the lower 3/4 of the stomach. Gastric pouch size and the length of the bypassed intestine determine the risks for ulcers, malnutrition and other effects.
Biliopancreatic Diversion with “Duodenal Switch”
This procedure is a variation of BPD in which stomach removal is restricted to the outer margin, leaving a sleeve of stomach with the pylorus and the beginning of the duodenum at its end. The duodenum, the first portion of the small intestine, is divided so that pancreatic and bile drainage is bypassed. The near end of the “alimentary limb” is then attached to the beginning of the duodenum, while the “common limb” is created in the same way as described above.
Gastric Bypass Roux-en-Y
In this procedure, stapling creates a small (15 to 20cc) stomach pouch. The remainder of the stomach is not removed, but is completely stapled shut and divided from the stomach pouch. The outlet from this newly formed pouch empties directly into the lower portion of the jejunum, thus bypassing calorie absorption. This is done by dividing the small intestine just beyond the duodenum for the purpose of bringing it up and constructing a connection with the newly formed stomach pouch. The other end is connected into the side of the Roux limb of the intestine creating the “Y” shape that gives the technique its name. The length of either segment of the intestine can be increased to produce lower or higher levels of malabsorption.
(taken from WeightLossSurgeryInfo.com)
You can read more about weight loss surgery and vitamin B-12 deficiency at ThinnerTimes Forum.
If you are considering weight loss surgery or have recently undergone weight loss surgery, be sure to discuss the possibility of vitamin B-12 deficiency with your doctor!