Just found this snippet of info - a good explanation of some of the vitamin deficiencies after gastric bypass. In my experience, all are true, I'm low in Vitamin B-12, Iron & Vitamin D.
"...the restrictive and malabsorptive gastric bypass procedure
commonly produce an increased risk of predictable nutrient deficiencies. There
are predictable deficiencies of vitamin B12, iron, folate, and calcium
absorption. Less common, are deficiencies in zinc and the fat soluble vitamins
A, D, and E.
Vitamin B12. Vitamin B-12 typically comes into the body bound
in a protein. The stomach secretes acid and Intrinsic factor which release the
Vitamin B-12 for absorption in the small intestine. The gastric pouch secretes
little if any stomach acid or Intrinsic Factor. Hence, it is very difficult for
the small intestine to separate and absorb Vitamin B-12.
Vitamin B12 deficiency has been reported to occur in greater than 30% of
gastric bypass patients a year after surgery.(1) Normally, vitamin B12
containing foods (meat, eggs, and milk) undergo acid and peptic hydrolysis in
the stomach to liberate vitamin B12. Once released, vitamin B12 is avidly bound
to R binders, which are glycoproteins secreted in saliva, gastric juice, bile,
and intestinal secretions. Pancreatic pro-teases then degrade R binders in the
duodenum and permit vitamin B12 to associate with intrinsic factor (IF). The
IF—vitamin B12 complex then is bound to specific receptors in the distal ileum,
where absorption occurs.
There is virtually no stomach acid secretion in the constructed gastric
pouch. Consequently, cobalamins are not liberated from protein and are not
available for intestinal absorption. Normal plasma cobalamin levels can be
usually maintained with oral supplemental vitamin B12. The inadequate levels of
secretion of IF and/or binding of cobalamins to R binders requires a bypass
patients to take daily oral supplementation of crystalline vitamin B12. Vitamin
B-12 is most effectively taken sublingually, i.e., a tablet that dissolves under
the tongue. Alternatively, monthly vitamin B12 shots may be administered.
Iron. Iron deficiency has been recorded to occur in 33% to 50%
of patients after a gastric bypass, with a greater incidence in menstruating
women.(1) Iron enters the body in two forms, heme or organic iron, which is
derived from animals, and non-heme, which is derived from plants and other
non-animal sources. The primary absorption spot for iron is the duodenum and
beginning of the jejunum.
The cause of iron deficiency is related to 1) reduced intake of organic (heme)
iron (gastric bypass patients tend to reduce their intake of animal products)
and 2) the bypassing of the acid environment of the stomach and absorptive
surface of the duodenum and upper jejunum. Organic iron is more soluble and
readily absorbed than inorganic iron. It must be liberated from its protein
structure by exposure to stomach acid and gastric juices. The bioavailability of
nonheme iron, or non-animal in origin, also depends on an acid environment where
the low pH of gastric secretions solubilizes iron by reducing it from the ferric
to the ferrous state for absorption in the duodenum and upper jejunum.
Since the gastric bypass patient has almost no stomach acid and both their
duodenum and upper jejunum are surgically bypassed, iron absorption is greatly
impeded. Thus, development of iron deficiency anemia is likely to occur in all
gastric bypass patients, especially in women who have concomitant menstrual
Iron absorption is increased or decreased by different factors. It is more
bioavailable when the iron is in an acidic environment. Taking an iron
supplement with Vitamin C, ascorbic acid, increases its absorption.
Iron absorption decreases when taken with coffee, tea or red wine. The
presence of calcium can also inhibit iron absorption. It is believed that
calcium and iron compete for the limited absorptive capability present in the
body.(2) If both iron and calcium supplements are to be taken, they should not
be taken within on hour of each other(3).
Folate. Folate deficiency is a common occurrence amongst the
population at large. One researcher has concluded "that over 44,000 lives could
be saved every year if just half the population of the United States were to
supplement with 400 micrograms per day of folic acid."(4) The best dietary
source for folate is, wouldn’t you know it, animal liver. Green leafy vegetables
are another good dietary source. Folate is absorbed primarily from the first
third of the small intestine, although it can be absorbed from the entire length
of small bowel(1). Since most, if not all of the first third of the small
intestine is bypassed because of gastric bypass alterations, gastric bypass
patients are more prone to folate deficiency.
Calcium. Calcium deficiency can result from several factors:
(1) reduced intake of calcium and vitamin D containing foods; (2) bypass of the
duodenum, where most calcium absorption typically occurs; and (3) malabsorption
of vitamin D due to mismixing of pancreatic and biliary juices in the
Unlike deficiencies of vitamin B12, iron, and folate, for which periodic
blood testing is a sensitive indicator of status, calcium deficiency is more
difficult to detect. Only 1% of the body’s calcium is in the blood stream, the
rest being in bones, teeth and marrow. When blood stream calcium is low, the
body regularly borrows calcium from bones and marrow. Consequently, blood stream
calcium is seldom low even when the body intake is insufficient. The blood
stream calcium may be adequate, but the bone calcium level has been depleted.
Hence, a blood test for calcium will not register a bone calcium deficiency. A
bone density scan is required to do this.
Many gastric bypass patients are unable to tolerate dairy foods because of an
underlying lactase deficiency. Since the majority of calcium comes from dairy
foods, which are also an important source of vitamin D, avoidance of these foods
can have a significantly impact on calcium absorption. Once ingested, calcium
normally is absorbed in the duodenum and proximal jejunum by an active saturable
process that is assisted by vitamin D. The surgical exclusion of these
intestinal segments from digestive system acts to diminish net calcium
Gastric bypass patients must therefore depend on a second and more passive
mechanism of calcium absorption to maintain bone health. This passive component
functions by simple absorption throughout the entire remaining small intestine.
Hence, within certain limits, an increase in dietary calcium will be followed by
a proportional increase in amount of calcium absorbed. When increasing calcium
supplementation, one should bear in mind that doses in excess of 400 mg have
little additional effect.(5) Calcium is absorbed in an inverse ratio, the more
calcium taken, the smaller the percentage that is absorbed. A dose of 100 mg has
a 41% absorption rate, but a dose of 2000 mg has an absorption rate of only
14-15%.(6) So more calcium is not necessarily better.
Two other factors can affect the bioavailability of calcium for a gastric
bypass patient. The first is the presence of Vitamin D. The presence of Vitamin
D increases the bioavailability of calcium. The body can make Vitamin D from
sunlight, but this ability decreases with age. A daily supplement of 400 mcg of
Vitamin D will enhance its absorption.
A second factor affecting calcium absorption is the form of the calcium.
Calcium is most commonly available as calcium carbonate and calcium citrate.
Calcium carbonate, table chalk, has a higher concentration of calcium and is
less expensive. However, calcium carbonate is not absorbed well in a non-acidic
environment. Calcium citrate has a much higher bioavailability rate than calcium
carbonate(7), particularly for gastric bypass patients who have little if any
stomach acid available to assist in absorption. Magnesium will also assist in
the absorption of calcium into the bones.
Gastric bypass patients should receive calcium supplements of 1000 to 1500
mg/d in divided doses. Calcium intake in amounts greater than 500 mg are not
absorbed. It is better to take three times a day than once a day. Calcium
citrate with vitamin D is the preferred preparation because it is more soluble
than calcium carbonate in the absence of gastric acid production.
Zinc. Zinc sometimes presents a problem because it is absorbed in the
duodenum with iron. The bypass of the duodenum reduces the opportunity for zinc
to be absorbed. This can largely be overcome by using a zinc amino acid chelate
supplement. A zinc amino acid chelate is a combination of two amino acid and one
zinc molecules. This compound is very small and easily slips through the lumen
of the small intestine. One inside the lumen, the body easily strips away the
amino acid leaving the zinc by itself.
The deficiencies in Vitamins A, C and E are not directly related to bariatric
surgery. The non weight loss surgery population often runs a deficiency in the
vitamins. Weight loss surgery patients will need slightly more Vitamin C,
ascorbic acid, to provide an acidic environment for iron absorption.