Iron Deficiency Post-Bariatric Surgery & How to Prevent It

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Iron is an important mineral essential for some of the body’s key functions. More specifically, iron is found in blood and helps to transport oxygen from the lungs to the rest of the body including all the organs such as the heart. Iron is also vital for helping to carry oxygen to muscles as well as for making hormones that the body needs to function appropriately.

When the body does not have enough iron, iron-deficiency anemia can develop. In these cases, red blood cells become smaller and carry less oxygen from the lungs throughout the body which can lead to a large variety of issues.


Why does iron deficiency occur in bariatric patients?

Iron deficiency is one of the most common nutrient deficiencies after weight-loss surgery (WLS) and is the number one cause of anemia in WLS patients. Iron deficiency is more common in patients who have had combination restrictive/malabsorptive surgeries (e.g., gastric bypass) rather than purely restrictive surgeries (e.g., gastric sleeve, gastric band) but can realistically occur after any type of weight-loss surgery.

There are several factors that contribute to iron deficiency after WLS, including:

  • A reduced tolerance for red meat, poultry, and seafood which is where a lot of dietary iron is attained
  • A reduced amount of stomach acid necessary for the reduction and absorption of iron
  • And a large segment of the small intestine is bypassed, or skipped, leading to less absorption of vitamins and minerals such as iron

How common is iron deficiency in bariatric patients?

Iron deficiency is one of the more common micronutrient deficiencies after WLS. According to studies, the incidence of iron deficiency 1 year after surgery is about 6% to 33% of WLS patients. After 2 years post-WLS, this incidence increases to about 40% of patients, and at 3-year follow-up, the incidence rises again to 54% of patients. This increase in the number of patients with iron deficiency years after WLS is often associated with patients who stop taking their multivitamin and other supplements despite doctor recommendations.

low iron blood

Who is most at risk for iron deficiency?

Although iron deficiency can occur in any type of patient after WLS, certain patients are more at risk for general deficiency and for developing iron-deficiency anemia.

These high-risk patients include:

  • Menstruating women because these women lose iron stores in their blood
  • Pregnant women because the need for iron increases as the baby grows to prevent preterm and low-birth-weight infants
  • Adolescents/children because of growth, poor diet, and menstrual blood loss

Symptoms of iron deficiency can be very nonspecific such as feelings of fatigue and decreased tolerance for exercise; symptoms common to post-WLS patients in general. But one very unique symptom associated with iron deficiency is pica, which is classified as an eating disorder in which the patient has an unusual craving to eat or chew on ice, cornstarch, clay, dirt, or other odd substances. Many iron-deficient patients may not have any symptoms at all and for this reason, follow-up with your doctor is crucial.

How to Prevent Iron Deficiency After WLS

It is important to take iron supplements as prescribed by your doctor before a deficiency arises because once a patient develops iron deficiency, oral supplementation of iron may not be enough to treat it and in very severe cases, patients may even require blood transfusions. For many patients, a multivitamin contains enough iron to prevent deficiency. Those patients who maintain low iron levels despite taking a multivitamin might have to take an additional iron supplement to correct the deficiency, especially those patients at high risk.

According to the American Society for Metabolic and Bariatric Surgery (ASMBS) guidelines, after bariatric surgery:

  • Patients at low risk for developing iron deficiency (i.e. usually males) should take at least 18 mg of elemental iron daily whether it be in a multivitamin or as a standalone vitamin.
  • Patients at higher risk, such as menstruating females and patients who have undergone malabsorptive procedures such as gastric bypass, should supplement with at least 45-60 mg of elemental iron daily.

When looking for a good iron supplement, you may find some that include ascorbic acid, or vitamin C. Some studies suggest that including vitamin C in an iron supplement increases the amount of iron that gets absorbed by the body. This might be because vitamin C increases the acidity of the digestive tract which is necessary for iron to be broken down and absorbed.

It is recommended that iron supplements be taken on an empty stomach with water or juice, but this can increase side effects such as nausea, upset stomach, and constipation. If upset stomach occurs, iron can be taken with food but not tea, cereal, dairy products, and other calcium-rich foods which can reduce iron absorption. Since an acidic environment is necessary for the absorption of iron, it’s also important to separate iron supplements from antacids such as Tums and Prilosec.

Finally, and most importantly, don’t forget to follow up with your doctor and pharmacist regarding follow-up appointments and any questions you may have about your medications and supplements. Remember that your health-care team is there to answer all your questions and to help guide you through your weight-loss journey!


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1 comment

  • Donna Brinkman

    Is the dose of 3 per day to MAINTAIN iron levels or to treat anemia? I’m anemic and trying to improve my iron levels and I’m wondering if I need to take more than 3 per day. Thank you.

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