Vitamins and micronutrient deficiencies are very common in patients who have undergone Roux-n-Y gastric bypass procedure.  Natural nutrients in food do not come in contact with the most active absorptive lining of proximal small intestine. Sometimes  patient may have pre-existing vitamins and minerals deficiencies like thiamin, vitamin B12,, folate, iron, vitamin D and calcium, fat-soluble vitamins (A, E, K), zinc, and copper.

Patients who develop symptoms suggestive of a micronutrient deficiency, or who have a micronutrient deficiency identified by screening laboratory tests, should be given appropriate repletion.

About ten percent of patients develop Vitamin A deficiency; they may experience night blindness,  poor healing and loss of taste. Late symptoms can include corneal damage, xerosis, or even blindness.

Patients should receive a vitamin A supplement of 5000 to 10,000 IU daily after gastric bypass surgery

Patients with vitamin A deficiency but without corneal changes should receive 10,000 to 25,000 IU daily orally until clinical improvement (one to two weeks); those with corneal changes should be given 50,000 to 100,000 IU daily intramuscularly for three days, followed by 50,000 IU/day for two weeks.

Vitamin D — Vitamin D deficiency has been reported in 90 percent of patients before and 100 percent of patients after bariatric surgery. Lack of vitamin D activity leads to reduced intestinal absorption of calcium and phosphorus. With persistent vitamin D deficiency, demineralization of bones, and, when prolonged and severe, to osteomalacia.

After bariatric surgery, patients should receive 3000 IU of D3 daily from all sources to maintain a 25 hydroxy vitamin D level of more than 30.

Patients with vitamin D deficiency should receive 3000 to 6000 IU of D3 daily (preferred), or 50,000 IU of D2 one to three times per week.

Vitamin E — A reported 2.2 percent of patients have a vitamin E deficiency before bariatric surgery. Vitamin E deficiency can cause neuromuscular disorders and hemolysis. Clinical manifestations include loss of balance and loss of vibratory sensation.

After bariatric surgery, adult patients and adolescents ages 14 and over should receive vitamin E supplements of 15 mg per day.

Patients with vitamin E deficiency should receive 100 to 400 IU daily (90 to 300 mg), although the optimal dose is not well established.

Vitamin K — Clinical signs and symptoms of vitamin K deficiency include easy bruisability, mucosal bleeding.Patients should receive daily supplements of 90 to 120 mcg of vitamin K after bariatric surgery.

Vitamin B1 (thiamine) — Vitamin B1 is absorbed primarily in the duodenum and proximal jejunum . RYGB patients are at a particularly elevated risk since their alimentary path bypasses the duodenum and proximal jejunum. Vitamin B1 deficiency may occur within three weeks after bariatric surgery in the patient with persistent vomiting or severely diminished oral intake.

Asymptomatic, abnormally low thiamine concentrations have been reported in 16 to 29 percent of preoperative patients. The most common manifestation of vitamin B1 deficiency in the post-bariatric bypass surgical population is Wernicke encephalopathy, a neurologic condition causing encephalopathy, oculomotor dysfunction, and gait ataxia.

Post-bariatric surgery patients should receive at least 12 mg of thiamin daily. Since over-the-counter multivitamins typically contain less than that amount, it is preferable for patients to take a B-complex supplement containing 50 mg of thiamine one or twice daily, in addition to a multivitamin.

Vitamin B12 — Recommended daily oral dose of vitamin B12 of 350 to 500 mcg for postoperative bariatric surgery management. Alternatively, patients can be treated with 1000 mcg of B12 intramuscularly or subcutaneously (monthly), or by nasal spray preparations . Peripheral neuropathy resulting from chronic vitamin B12 deficiency may not be reversible and must be prevented by diligent laboratory monitoring and adequate replacement. Since the body has a 12- to 18-month storage of vitamin B12, B12 deficiency is identified approximately two years or more following surgery; therefore, yearly long-term laboratory monitoring is essential.

Patients with B12 deficiency should receive 1000 mcg of B12 daily until the level is normalized before resuming maintenance doses.

Folate — Folate deficiency, which also induces megaloblastic anemia, is less common than vitamin B12 deficiency since folic acid is absorbed throughout the entire small intestine.

Supplementation is typically provided as a daily oral dose of 400 to 800 mcg, usually as a part of a multivitamin.

Patients with B12 deficiency should receive 1000 mcg daily until the level is normalized before maintenance doses can be resumed. Folate supplementation above 1 mg per day is not recommended due to the potential masking of vitamin B12 deficiency.

Trace minerals — Minerals form only 5 percent of the typical human diet but are essential for normal health and function. Macrominerals are defined as minerals that are required by adults in amounts greater than 100 mg/day or that make up less than 1 percent of total body weight. Trace elements (or trace minerals) are usually defined as minerals that are required in amounts between 1 to 100 mg/day by adults or make up less than 0.01 percent of total body weight. Ultra-trace minerals generally are defined as minerals that are required in amounts less than 1 mg/day.

Iron — Iron deficiency is one of the most common nutritional problems following bariatric surgery and results in hypochromic and microcytic anemia. Iron is primarily absorbed in the duodenum and proximal jejunum; bariatric bypass operations, Iron deficiency is identified in 0 to 58 percent of patients with obesity preoperatively and 8 to 50 percent of postoperative bariatric patients, particularly in women who are still menstruating.

After bariatric surgery, males and patients without history of anemia should receive at least 18 mg of iron from a multivitamin. Menstruating females and those who have undergone RYGB, should take at least 45 to 60 mg of elemental iron daily. Most multivitamins do not have enough iron in the elemental form to achieve this level of supplementation. Taking vitamin C with iron increases absorption; calcium supplements and foods containing high amounts of calcium will decrease absorption.

Post-bariatric surgery patients with iron deficiency should start with 150 to 300 mg of iron orally two to three times daily. Iron infusions may be indicated in postoperative patients who have chronic iron deficiency and/or cannot tolerate the amount of oral iron supplements needed for repletion.

Zinc — Zinc, like other divalent cations, is absorbed in the duodenum and proximal jejunum and linked to fat absorption. Zinc deficiency results in growth retardation, delayed sexual maturity, impotence, and impaired immune function, among other medical conditions.

Copper — Copper is absorbed in the stomach and proximal duodenum. It is required for red and white blood cell production and for normal functioning of the nervous system. Copper deficiency results in microcytic anemia, neutropenia, and ataxia and is worsened by iron supplements.

A ratio of 1 mg copper supplementation has been recommended for every 8 to 15 mg of elemental zinc to prevent copper deficiency.

●Mild-to-moderate deficiency: 3 to 8 mg copper orally until levels normalize

●Severe deficiency: 2 to 4 mg copper intravenously for six days or until symptoms resolve

Selenium deficiency has been reported in 14 percent of patients following an RYGB.  The optimal range for dietary intake of selenium is narrow; potentially toxic intakes are closer to recommended dietary intakes than for other dietary trace minerals.

●To prevent micronutrient deficiency, patients should receive daily vitamin and mineral supplementation determined by the bariatric procedure after bariatric surgery.

●Patients with symptoms suggestive or a laboratory test diagnostic of a micronutrient deficiency should receive repletion of that micronutrient