Nutrient Deficiencies and Health
Consequences
Part II: Gastric Bypass and Duodenal Switch
Cynthia Buffington, Ph.D.
Beyond Change, August 2002
Nutrient deficiencies following bariatric
surgical procedures can lead to serious health consequences if left unattended.
In last monthâs issue of Beyond Change, pre-operative nutritional
deficiencies and those following gastric restrictive surgeries (gastric band,
gastroplasty procedures) were discussed, along with suggestions for nutrient
management. This month, nutrient deficiencies following surgeries that contain
a malabsorptive component, such as the gastric bypass and duodenal switch, are
addressed.
Gastric bypass combines both
gastric restriction and malabsorption to induce massive and sustained weight
loss. With the gastric bypass, the amount of food one can consume is reduced
considerably by formation of a small gastric pouch (small stomach) that holds
only 2-3 tablespoons of food. In addition, a ring with a small diameter is
often placed at the junction between the stomach pouch and intestine to slow
the rate that food leaves the pouch, causing one to feel âfullâ for
a longer period of time.
With the gastric bypass procedure,
the part of the stomach that produces acid and digestive enzymes is bypassed
(food no longer passes through), and the newly formed small gastric pouch
produces negligible amounts of acid and digestive enzymes. Without stomach acid
and digestive enzymes, certain foods are not adequately broken down to release
their nutrient content.
The small stomach pouch also
produces no intrinsic factor, an agent that must bind to vitamin B12 for its
absorption from the gut into the body. The gastric bypass procedure, therefore,
causes deficiencies in vitamin B12, the vitamin that assists in the metabolism
of food (carbohydrate, fat, and protein), DNA replication and repair, nerve
conductance and function, the formation of blood cells, and more.
The malabsorptive component of the
surgery includes bypass of the upper portion of the intestines (the duodenum)
along with a portion of the jejunum (the second major segment of the gut).
Bypass of the duodenum causes malabsorption of, and therefore deficiencies in,
iron, calcium, zinc, and folate. Other B-complex vitamins are also reduced with
gastric bypass, both as a result of decreased absorption and to reduced
nutrient intake and digestion. Furthermore, the gastric bypass procedure
reduces fat absorption which may, consequently, cause deficiencies of
fat-soluble vitamins, including vitamins D, E, K, and A.
Studies have shown that daily
multivitamin and mineral supplements, at amounts close to the RDI (Recommended
Daily Intake), correct most micronutrient deficiencies following gastric bypass
surgery, with the exception of zinc, calcium, iron, folate, and vitamin B12.
These vitamins and minerals generally require supplementation at amounts
greater than the RDI.
Several studies have found that,
even with supplementation, iron deficiencies occur in 30% to 60% of the gastric
bypass population. Iron deficiencies occur for males, as well as females,
but are more common among pre-menopausal females. Within the first two
years following surgery, 30-40% of gastric bypass patients have been reported
to suffer from anemia secondary to poor iron absorption.
Iron deficiencies may be prevented
with iron taken at amounts given to women during pregnancy, ~40 mg. Iron as
ferrous fumerate or chelated to amino acids are the most readily absorbable
forms of supplemental iron. And, heme iron, obtained from eating meat, is far
more readily absorbed by the gut than is non-heme iron from plants or
supplemental sources.
Approximately 20% of the gastric
bypass population is likely to develop folate deficiencies. Such deficiencies
can be corrected or prevented by intake of supplemental folate at 800 to 1000
micro-grams (µg) per day or approximately 200% the RDI.
Vitamin B12 deficiencies occur in
up to 70% of patients, with as many as 30% of patients having such deficiency
while on supplements that meet the B12 RDI. As mentioned earlier, the
small gastric pouch does not produce intrinsic factor necessary to bind B12 for
its absorption out of the gut and into the body.
Studies have found that B12
deficiencies, for the majority of gastric bypass patients, can be prevented or
effectively treated with B12 supplements in amounts that are high enough to
cause passive diffusion of B12 across the gut in the absence of intrinsic
factor. B12 supplemented at amounts far in excess of the RDI (as high as 100 to
350 micrograms) have been found to prevent B12 deficiencies in >95% of
post-surgical gastric bypass patients.
Sublingual B12 (under the tongue)
taken daily may also be effective in the prevention of B12 deficiencies since
the vitamin is absorbed into the blood stream and does not need to bind to
intrinsic factor for absorption. B12 shots taken daily or monthly are also
effective in bypassing impaired B12 absorption and in preventing and treating
B12 deficits.
Defects in folate and B12 may
cause anemia (pernicious anemia), as well as elevated production of
homocysteine and concomitant increased risk of cardiovascular disease. Symptoms
of folate deficiency include: weakness, headache, palpitations, forgetfulness,
hostility, irritability, paranoid behavior, apathy, sore tongue,
gastrointestinal tract disturbances and diarrhea.
B12 deficiencies may also cause
gastrointestinal disorders, such as diarrhea, cramping, constipation, as well
as palpitations, shortness of breath, and extreme fatigue. Neurological
deficits secondary to B12 deficiencies include impaired bladder control,
numbness, tingling of the extremities, moodiness, agitation, disorientation,
insomnia, confusion, dimmed vision and even delusions and hallucinations.
Some of these neurological deficits caused by B12 deficiencies may be
irreversible.
Calcium deficiencies occur
following gastric bypass for several reasons. First, the portion of the
gut where calcium is actively absorbed (the duodenum) is bypassed by the
surgical procedure. Secondly, there is insufficient acid produced by the small
stomach pouch to provide enough acid in the gut for appropriate calcium
absorption. Third, changes made in the mixing of food with pancreatic juices
may alter vitamin D absorption. And, finally, some patients become lactose
intolerant after surgery and avoid dairy products.
Low calcium is known to cause bone
loss. Recent studies have also found that low calcium intake is associated with
weight gain. Calcium supplements may, therefore, not only prevent bone loss but
also assist in promoting weight loss and preventing weight regain following
bariatric surgery.
Calcium supplements of 1200 mg to
2000 mg taken in 400-500 mg aliquots 3 times per day are recommended for
individuals who have had gastric bypass surgery. Calcium citrate, rather than
calcium carbonate, is more readily absorbed in the non-acidic environment of
the gut of the gastric bypass patient. Absorption is further enhanced by
calcium supplements that include vitamin D or magnesium.
The high risk for B12, folate,
iron deficiencies following gastric bypass requires that the individual have
periodic tests (annually) for blood levels of ferritin (iron), folate and
B12. Blood tests for measurement of blood calcium are unreliable. When
blood calcium is low, the body âborrowsâ calcium from bone and
teeth so that levels may appear ânormalâ. Thus, it is wise for the
gastric bypass patient to occasionally have a bone scan, a bone
demineralization test, or some other test that can be used as a marker for low
calcium.
Protein deficiencies are common
with gastric bypass and occur secondary to: 1) low calorie intake, 2) avoidance
of meat, 3) negligible acid and digestive enzymes produced by the stomach, and
4) reduced absorption of protein by the bypassed gut. Low protein intake
after surgery can cause muscle loss which, in turn, leads to a reduction in
basal metabolic rate (reduced amount of calories burned at rest), interfering
with maximal weight loss success. The heart is also a muscle and can lose
tissue with severe protein deficiencies. For these reasons, protein supplements
and high intake of protein is encouraged for all gastric bypass patients - and
for life.
More and more patients in the
United States are choosing the biliopancreatic diversion with the duodenal
switch for weight loss surgery. The individual who has had the duodenal switch
can eat normally because the portion of the stomach that produces digestive
enzymes and acids is reduced but not bypassed. Weight loss with this procedure
is caused primarily by malabsorption through bypass of a larger portion of the
gut.
Possible nutrient problems
following the duodenal switch which may occur without nutrient supplementation
include the following: protein deficiencies, low levels of fat-soluble vitamins
(A, E, D, K), low amounts of B-complex vitamins, low minerals and, in
particular, calcium, iron, and folate deficiencies. Such deficiencies can lead
to muscle and bone loss, anemia, neurological defects, high oxidative stress
and associated risk for disease, and more. To avoid such nutrient deficits with
the duodenal switch, high protein diets or protein supplements and daily
vitamins and minerals are required for life.
In summary, nutrient deficiencies
following the gastric bypass and duodenal switch are common and can lead to
serious health consequences if left unattended. Increased intake of protein or
protein supplementation is necessary long-term following these procedures.
Vitamin and mineral supplements at RDI levels for most micronutrients, or
greater than RDI for specific ones (calcium, iron, folate, zinc, B12), are
required for life. Because nutrient deficiencies have very serious and often
irreversible health consequences, periodic vitamin and mineral blood tests are
necessary on a periodic basis, i.e. usually annually.
Comments: 60 mins after food/protein bar + flax bread
