During surgery, the weight loss surgeon re-arranges the guts in order to change the genetic predisposition of a person from being obese to being thin. While we cannot change the environmental factors in the person’s life that caused him or her to be obese, we can re-route the system a bit to aid the patient with losing pounds. As a result, a number of vitamins and minerals will need supplementation. This chapter provides an A-Z guide for weight loss surgery patients and their primary care physicians on what supplements are needed for the different types of weight loss surgeries, and how to check for deficiencies.

Theme to all weight loss surgeries—

It is easy to prevent, it is not easy to treat!

No matter which weight loss surgery you have, or had, preventing a deficiency is fairly simple—in most cases it simply involves taking a vitamin, and in some other cases it may involve taking shots (not Tequila, either). Treating them is not easy, and is not simply taking a vitamin. No matter which weight loss surgery you have, you should take supplements. If you don’t take them, you can become very sick, you can become permanently disabled, and you can die.

Iron deficiency in RNY gastric bypass patients

Iron is absorbed in the duodenum primarily, but it is also absorbed in the small bowel. Some patients with duodenal switch, therefore, will have no problem with iron levels, but this is variable. RNY gastric bypass patients are particularly prone to iron malabsorption. Some studies have suggested that menstruating women should take iron twice a day, as either ferrous sulfate or ferrous gluconate (300-350 mg per day). Ferrous fumarate, used in Chromagen® Forte Capsules, is an organic iron complex which has the highest elemental iron content of any hematinic salt – 33%. This compares with 20% for ferrous sulfate (heptahydrate) and 13% for ferrous gluconate.1,2 Chromagen® Forte contains 151 mg of elemental iron. While this still will not completely prevent iron shortage, it greatly reduces the number of weight loss surgery patients who will have problems with it.

Iron containing foods include meats, poultry, oysters, rusty nails, and dark leafy vegetables.

Recommended tests for post-op weight loss surgery patients

Complete Blood Count (CBC) every six months first two years, then yearly thereafter. If anemia is found then additional tests include serum ferritin. Bone marrow examination is the most specific, but serum ferritin levels are proportional to marrow iron and inversely proportional to transferrin levels. Iron deficiencies, and decreased stores, are associated with ferritin levels below 15ng/mL in men, and 10ng/mL in women. Values between 15ng/mL and 100ng/mL can indicate deficiency in weight loss surgery patients with an inflammatory process. Inflammation can lead to falsely high ferritin levels. In people who have inflammatory process which is ongoing, treatment with iron, and the response to the therapy, may be the best diagnostic approach, short of bone marrow stains.

Serum iron and binding capacity are often ordered at the same time, and they may confirm an inadequate iron store. Elevated red cell distribution width (seen on CBC) may be helpful in monitoring response to therapy, but is inadequate to determine iron shortages.

Treatment of vitamin and mineral deficiencies in weight loss surgery patients


Treatment of iron deficiency—rusty nails

Treatment of iron shortages can be complicated with post operative bariatric surgery patients. Oral iron is inexpensive, and can be tried for several months. Iron absorption is aided with the addition of vitamin C, and is mildly inhibited with calcium. The addition of 500 mg of vitamin C with the iron increase iron absorption. But with many weight loss surgery patients, oral intake will not produce a fast enough response. Sometimes iron must be taken through shots (intramuscular or intravenous). These people should be watched carefully to avoid iron overload. The body becomes very efficient at absorbing iron if it is deficient.

Vitamin B1 (Thiamin) deficiency

While this is readily available in multivitamins, a shortage of this simple vitamin can cause severe neurologic problems (Wernicke’s syndrome). Early symptoms of Thiamin deficiency can be headaches, anorexia, weakness, edema, lowered blood pressure, low body temperature, nausea, and muscle aches and pains. Weight loss surgery patients who have persistent vomiting, or difficulty eating, or those rare people who become anorectic, can develop severe syndromes such as Wernicke’s. Wernicke’s is manifested as depression, inability to concentrate or to learn, hallucinations, confabulation (making up stories unintentionally—unlike fishermen), and ultimately by difficulty walking (gait) and even dementia. Ultimately weight loss surgery patients can also develop Beriberi, heart failure and peripheral edema.

Tests for Vitamin B1 levels are expensive and take time, and treatment is quite simple. If a weight loss surgery patient is having difficulty with nausea and anorexia, thiamine is available as a pill or in injectable forms. Just as we do not give glucose without thiamin for alcoholic people, giving glucose without thiamin for patients who have been vomiting and may malabsorb can induce a Wernicke’s. Since the vitamin is water soluble, no toxic effects have been reported in humans.

Vitamin B12 (Cobalamin)

When I was a young man, it was a popular thing for people to go see the doctor for their monthly B12 injection to give them energy. They probably didn’t need it, but a pat on the back by our small-town physician and a shot was something that made a lot of them feel pretty good. B12 deficiency in patients who have had weight loss surgery can be a real issue, however, and one which is easy to prevent.

While the liver stores a lot of B12, the previous estimate that bariatric patients have adequate stores for a year or longer are probably incorrect. Most B12 shortages are manifested in weight loss surgery patients within about three months. B12 is a necessary vitamin to build healthy blood cells, without it anemia will occur. To absorb B12 it Most B12 shortages are manifested in weight loss surgery patients within about three monthshas to be combined with a factor in the stomach called “intrinsic factor,” hence, RNY gastric bypass patients have a propensity to develop this deficiency.

Symptoms are manifested by weakness, fatigue, and shortness of breath—all of which are secondary to the anemia. Other signs include a sore tongue, lack of taste, some heartburn, numbness, hair loss, impotence, irritability and memory disturbances. Depression is a common manifestation of this. Jaundice can also occur with a shortage of B12. Blood cells are broken down, but unable to be made, so one of the breakdown products, bilirubin, makes you yellow. The problem with jaundice is that it is so hard to find clothes to match the yellow color.

Treatment can yield impressive results with a single injection of 100μg after 24 hours. Before beginning therapy, however, it is important to confirm the diagnosis. The patient should be followed with a hemoglobin, hematocrit, erythrocyte, and reticulocyte count.

Once the clinical symptoms have improved, and the blood count is returning to normal, a monthly maintenance dose of 100 to 200 mcg will be sufficient to maintain the patient. Weight loss surgery patients who have this need to have lifelong therapy, while they can store the drug for a while, they need to understand that this is something they will need for the rest of their life.

The Schilling test reflects absorption of B12. Serum B12 can be checked directly which correlates with body stores. A serum level of less than 140 pg/mL is always associated with low body stores; however, this can be altered if the weight loss surgery patient has a protein deficiency or a shortage of folate. Hence, with ordering a serum B12 level we recommend a serum methylmalonic acid and total homocysteine level. The Schilling test is rarely, if ever, used today. Often we use B12 levels and serum methylmalonic acid levels and serum homocystine levels instead.

Vitamin B6 deficiency: increased homocysteine, and decreased d-cystathionine. Folate shorages will show increased homocysteine, and decreased 2-methyl citric acid. Cobalamin (B12) shortages will show increased homocysteine and increased methylmalonic acid.

Vitamin B6

This is a complicated vitamin, which is produced in the upper intestine, and malabsorption is a known cause for its deficiency. Too much of the vitamin can lead to a neuropathy, so it is one of those where too much can be a bad thing. A shorgage of this vitamin is also with non-specific symptoms such as seborrhea-like lesions around the eyes, nose, mouth; glossitis; hypochromic anemia; peripheral neuritis. Other symptoms such as nausea and vomiting, dizziness and insomnia have been described. One can order a Vitamin B6 level, although replacement therapy with a B complex, if this is suspected, is fairly simple. RBC folate levels are very helpful.


Ever notice that most of these B vitamins have some of the same symptoms? Anorexia, nausea, diarrhea, mouth ulcers, hair loss, fatigue, a sore tongue, and an anemia are all signs of folate deficiency. Folate deficiency is a real problem for women who wish to become pregnant, as a class of birth defects, known as neural tube defects, is associated with a shortage of folate (spina bifida type). Again, something that is easy to prevent. Serum homocysteine (but not methylmalonic acid) levels are elevated in when there is a shortage of folate.