The number of patients post-bariatric surgery is increasing. It is important for all physicians to be aware of the nutritional needs of these patients. This article is directed at plastic surgeons (see reference below), but would be of value to all of us.
The aim of this article is to highlight the nutritional deficiencies of the weight loss surgery patient as they may relate to the patient's subsequent planned plastic surgery procedures. The clinical manifestation of these nutritional deficiencies and their prevention and treatment are the subjects of a subsequent publication
The article begins by noting that the two most common bariatric operations are the laparoscopic adjustable banding and the Roux-en-Y gastric bypass.
Laparoscopic adjustable banding is a restrictive procedure, in which a small gastric pouch with a small outlet is created, resulting in early and prolonged satiety. Because the normal absorptive surface is left intact, specific nutrient deficiencies are rare.
The Roux-en-Y gastric bypass procedure involves both restrictive and malabsorptive components. The stomach size is decreased to less than 30 ml with a 75- to 150-cm Roux-limb connected as an enteroenterostomy to the jejunum. By reducing the stomach, the patient loses storage capacity and hydrochloric acid, pepsinogen, intrinsic factor, gastrin, and mucus. In addition, elimination of the body of the stomach severely restricts the process of food grinding, which is important in releasing vitamins and minerals. By forming the Roux-en-Y anastomosis, the coordination between gastric emptying and release of pancreatic enzymes is lost, which could lead to maldigestion and malabsorption. Finally, bypassing the duodenum and proximal jejunum leads to diminished absorptive surface area.
The method used for this article was a review of an extensive literature search using PubMed and Ovid databases. It used search terms including "bariatric surgery" and "nutrition". It covered over 600 articles from 1980 to present.
It is important to know which weight-loss procedure the patient had.
Because the small intestine remains intact after vertical banded gastroplasty, micronutrient deficiencies are rare provided that adequate food intake is maintained.
In contrast, micronutrient deficiencies are common in Roux-en-Y gastric bypass and biliopancreatic diversion.
Vitamin B12 plays an important role in DNA synthesis and neurologic function. Vitamin B12 deficiency and folate deficiency are fairly prevalent after bariatric operations as early as 6 months postoperatively but most commonly at 12 months or longer.
Vitamin B12 and folate deficiencies occur most often in Roux-en-Y gastric bypass patients, although other malabsorptive procedures can also increase the risk.
Absorption of dietary vitamin B12 is a complex process that requires an intact stomach, coordinated pancreatic enzyme release, and an adequate length of terminal ileum.
Roux-en-Y gastric bypass alters the physiologic mechanisms of vitamin B12 absorption in several ways. It alters consumption of meat, milk, and other foods that contain a high level of vitamin B12.
Decreased gastric acid and pepsin hydrolysis results in incomplete liberation of food-bound vitamin B12.
Bypassing of the duodenum results in incomplete release of vitamin B12 from salivary R-binder proteins by the pancreatic enzymes.
Finally, reduced intrinsic factor (from the parietal cells) release causes diminished absorption of vitamin B12 at the terminal ileum.
The recommended daily allowance for vitamin B12 is 2.4 microgram/day. The majority of Roux-en-Y gastric bypass patients cannot maintain normal vitamin B12 levels with an oral diet alone and will require supplementation. It is important to stress to our patients the importance of supplemental vitamins.
Because only approximately 1% of free vitamin B12 is absorbed, recommendations for postsurgical patients range from 500 to 600 micrograms/day in an oral form or 100 micrograms monthly by means of intramuscular injection. Despite the recommended B12 supplementation, 3.6 percent of post–laparoscopic Roux-en-Y gastric bypass patients continue to be deficient in vitamin B12 at 1 year.
Folate is a generic term for the water-soluble B-complex vitamin that exists in many different forms. It is an essential cofactor in metabolic pathways, especially amino acid conversion and DNAsynthesis, and is necessary for erythrocyte formation and growth.
Serum folate deficiency has been observed in 45% of obese patients before gastric bypass surgery and 9 to 35% after bypass operations. It appears to be less common than vitamin B12 and iron deficiencies.
Folate is found in green leafy vegetables, liver, and yeast. It's absorption in the intestines is inhibited at high intraluminal pH (alkali environment) in the absence of the gastric hydrochloric acid. In Roux-en-Y gastric bypass, malabsorption and short bowel can quickly lead to deficiency if folate is not continuously supplemented.
Similar to vitamin B12, most Roux-en-Y gastric bypass patients with folate deficiency are asymptomatic or suffer from subclinical disease. However, those with severe deficiency can present with megaloblastic anemia.
This can be prevented by ingestion of regular vitamin preparations, containing 400 micrograms of folate, after Roux-en-Y gastric bypass.
Vitamin B1 (Thiamine)
Thiamine is a water-soluble vitamin obtained in the diet chiefly through plant sources. Deficiencies lead to impaired digestive function in mild cases and beriberi (cardiac or nervous system dysfunction) in severe cases. Thiamine is absorbed in the small intestine, mostly in the jejunum and ileum. In post– bariatric surgery patients, however, thiamine deficiency is likely to be subclinical.
Thiamine deficiency is particularly associated with vertical banded gastroplasty procedures because of reduced dietary intake.In Roux-en-Y gastric bypass patients on vitamin supplementation, the incidence of thiamine deficiency was 18.3 and 11.2 % at the 1- and 2-year follow-up, respectively.However, clinical manifestations (e.g., weakness, peripheral neuropathy) are rare and were seen in only two of the 493 patients (0.4 %). The development of Wernicke encephalopathy is a rare long-term complication of weight loss surgery.
A multivitamin supplement is usually adequate in preventing thiamine deficiency. If deficiency occurs, it should be treated with parenteral thiamine, 50 to 200 mg/day until symptoms clear and then 10 to 100 mg by mouth daily.
Vitamin B2 (Riboflavin)
A water-soluble vitamin obtained in the diet through dairy products, green vegetables and meats. Riboflavin is not stored in ample amounts and thus a constant supply is needed. Deficiency in this vitamin is usually part of a multiple-nutrient deficiency and does not occur in isolation. Deficiencies lead to various problems including skin atrophy and cataracts.
It has recently been reported that riboflavin deficiency in Roux-en-Y gastric bypass patients was13.6 and 7.1% at the 1- and 2-year follow-up, respectively, despite vitamin supplementation.
Deficiency should be treated by 6 to 30 mg of riboflavin by mouth daily.
Vitamin B6 (Pyridoxine)
A water-soluble vitamin that is widely distributed in all foods. It is involved in the metabolism of some amino acids (building blocks of protein). In particular, it has been used to treat elevated homocysteine levels in the blood - an emerging heart disease risk factor. Deficiencies are rarely seen due to its ubiquitous nature; however, this can occur in some genetic defects and medication side-effects (e.g. isoniazid used to treat tuberculosis).
Despite vitamin supplementation, Clements et al have recently shown deficiency of vitamin B6 in 17.6 and 14.2% of post–laparoscopic Roux-en-Y gastric bypass patients at the 1- and 2-year follow-up, respectively.
Recommendation for treatment of deficiency is variable and depends on the clinical presentation. Recommended daily intakes for men and women over 50 years of age are 1.7 and 1.5 milligrams/day, respectively. For all younger adults 1.3 milligrams/day. Upper intake levels are established for all adults at 100 milligrams/day. Intake of 2000-5000 milligrams/day for months has caused central nervous system dysfunction.
MALABSORPTION OF FAT-SOLUBLE VITAMINS
The high degree of fat malabsorption associated with biliopancreatic diversion and Roux-en-Y gastric bypass tends to also cause malabsorption of fat-soluble vitamins, such as vitamins A, D, and K.
A fat-soluble vitamin formed from the yellow pigments of plants (alpha, beta, and gamma carotene). It is essential for sound skin, tooth and bone health and development; it is also important in immune system function and the prevention of night blindness. It is found in animal fats, liver, carrots, tubers, and green leafy vegetables.
Dolan et al.21 reported vitamin A deficiency in 61% of patients following biliopancreatic diversion at 28-month follow-up. This was despite an 80% compliance rate with multivitamin supplementation.
Brolin and Leung observed that prophylactic supplementation of vitamin A did not prevent deficiency in up to 10% of those patients who had distal Roux-en-Y gastric bypass after 2 years.Similarly, the incidence of vitamin A deficiency was 11 and 8.3% at the 1- and 2-year follow-up, respectively,despite vitamin supplementation.
The recommended daily allowance of vitamin A is approximately 3000 IU for men and 2300 IU for women, respectively. Although the recommended daily allowance is designed to meet the needs of the majority of healthy individuals, this amount may not be optimal for the post– bariatric surgery patient.
Calcium and Vitamin D
As with the other micronutrients, patients undergoing malabsorptive procedures are at higher risk of calcium and vitamin D deficiencies than patients who undergo a restrictive procedure.
Calcium is mostly absorbed in the proximal small intestine by an active, saturable process mediated by vitamin D. Bypassing these sections of the small intestine, along with reduced calcium and vitamin D intake, can lead to calcium deficiency.
The incidence of vitamin D deficiency in purely malabsorptive procedures varies from 17% at 9 to 18 months to 63% at 4 years after surgery.
The incidence in distal Roux-en-Y gastric bypass, which is a combination of restrictive and malabsorption procedures, was significantly higher.
Despite calcium and vitamin D supplementation after Roux-en-Y gastric bypass, Coates et al. found that within 3 to 9 months after surgery, patients have an increase in bone resorption associated with a decrease in bone mass.
Supplementation is recommended for all Roux-en-Y gastric bypass and biliopancreatic diversion patients. Current recommendations range from 1000 to 1500 mg/day for calcium and 8 micrograms/day for vitamin D.
A fat-soluble vitamin that aids in blood coagulation. It is found in fats, green vegetables, and various grains. Deficiencies are very uncommon, but can lead to hemorrhaging.
A study of 170 patients following biliopancreatic diversion and biliopancreatic diversion with duodenal switch found that the incidence of vitamin K deficiency was 68% by the fourth year. However, there was no clinical manifestation of increased bleeding.
Data are lacking on vitamin K deficiency in other weight loss surgery procedures, its implications, and recommendations on treatment in post– bariatric surgery patients.
Iron is an essential mineral and an important component of proteins involved in oxygen transport and metabolism. Iron is also an essential cofactor in the synthesis of neurotransmitters such as dopamine, norepinephrine, and serotonin. About 15% of the body's iron is stored for future needs and mobilized when dietary intake is inadequate. The body usually maintains normal iron status by controlling the amount of iron absorbed from food. This is interrupted by the restrictive and malabsorptive procedures used for weight loss.
The incidence of iron deficiency in Roux-en-Y gastric bypass patients has been estimated to be between 30 and 50% and is higher in menstruating women.
Dietary iron is ingested in animal hemoglobin and myoglobulin (heme iron) or as plant inorganic iron. Heme iron is absorbed directly by intestinal mucosal cells after removal of the globin by proteolytic duodenal enzymes. In contrast, nonheme iron is first reduced from the ferric to the ferrous state by gastric hydrochloric acid for absorption in the duodenum and jejunum.
In Roux-en-Y gastric bypass patients, the pathophysiology of this deficiency is related to reduced intake of iron, bypassing the acid environment of the stomach, and reduced absorptive surface of the small intestine.
The recommended daily allowance for iron for men and nonmenstruating women is 10 and 15 mg/day, respectively. Roux-en-Y gastric bypass patients with limited energy intake of 1000 to 1500 kcal/day may only consume 6 to 9mg of iron from food ingested daily. Patients are usually treated with oral ferrous sulfate/gluconate. Many of the newer preparations also contain vitamin C to promote iron absorption and can be taken as single daily doses of 100 to 200 mg of elemental iron.
Occasionally, patients who are refractory to oral iron supplementation require parenteral iron infusions.
Zinc is an essential trace mineral that is required for cellular growth and replication. Major food sources for zinc are proteins, and there is a direct correlation between dietary protein and zinc intake. Approximately 30 % of ingested zinc is absorbed from the small intestine.
A report by Madan et al. demonstrated a significant deficiency of this trace element in 30% of 100 preoperative morbid patients. Postoperatively, this increased to 36 % despite vitamin supplementation of the diet. In post– bariatric surgery patients, zinc deficiency is often subclinical and only manifests itself as hair thinning and loss.
The recommended daily allowance for zinc is 11 mg/day for men and 8 mg/day for women.
Nutritional Deficiency of Post-Bariatric Surgery Body Contouring Patients: What Every Plastic Surgeon Should Know; Plastic and Reconstructive Surgery:Volume 122(2)August 2008pp 604-613; Agha-Mohammadi, Siamak M.B., B.Chir., Ph.D.; Hurwitz, Dennis J. M.D.
Blog Posts on Bariatric Surgery
Chris Oliver Blogspot (an orthopaedic surgeon who writes his story post-banding)