Iron Deficiency After Metabolic and Bariatric Surgery

iron deficiency after metabolic and bariatric surgery

Did you know that the prevalence of iron deficiency after metabolic and bariatric surgery (MBS) can range from 1 to 54% of individuals? (1)

The outcome of gastric surgery for weight loss comes with the risk of micronutrient deficiencies, including iron. Fortunately, there are evidence-based guidelines that recommend certain nutrient levels that can commonly be found in bariatric-specific supplements to support vitamin and mineral levels. (2)* 

In this blog, we discuss the importance of iron, why deficiency is common after metabolic and bariatric surgery, symptoms of deficiency, and different forms of iron.  

What Does Iron do?

Iron is a mineral that plays many roles in the body, but its main function is in the production of red blood cells. Without iron, your body cannot produce enough hemoglobin and myoglobin (components in red blood cells) to carry oxygen from your lungs to body tissues and muscles. 

The American Society for Metabolic and Bariatric Surgery (ASMBS) guidelines recommend that most patients get 45-60 mg of elemental iron daily. The recommendation can differ based on the surgery performed, history of anemia, age and sex of the patient. (2)

Why is Iron Deficiency Common After Metabolic and Bariatric Surgery?

MBS results in restriction, malabsorption or a combination of both. Iron deficiency is usually more common for patients with gastric bypass than patients with sleeve gastrectomy and gastric band. The increased risk of deficiency is caused by:

  • Malabsorption due to the bypassing of the duodenum and proximal jejunum. This area of the small intestine is where a majority of iron is absorbed causing a higher risk of deficiency.
  • Decreased stomach acid after surgery. Stomach acid helps to change iron into a form that is readily absorbed by the body.
  • Tolerance and compliance issues with recommended iron supplements.*

To support iron within normal ranges, patients usually require a bioavailable form and high dose of iron that may not be found in a typical multivitamin.*

Iron can also be consumed through dietary sources. It's important to follow a diet that offers variety and essential nutrients, such as iron to support proper nutrition. 

Symptoms of Iron Deficiency

It's important to catch low vitamin/mineral levels or deficiencies before surgery to support optimal recovery post-op. 

Studies have shown that iron deficiency can appear a few years after metabolic and bariatric procedures. (3) Symptoms of iron deficiency are:

  • Anemia
  • Brittle nails
  • Headaches and confusion
  • Constipation
  • Dizziness 
  • Fatigue
  • Unusual cravings (Pica)

It is necessary to obtain lab work regularly and follow-up with your healthcare provider. 

Vitamin C and Iron Absorption

Foods and dietary supplements containing vitamin C can support absorption of iron.* Some food sources of vitamin C include: 

  • Red bell peppers
  • Oranges
  • Broccoli
  • Strawberries 

An iron supplement that contains vitamin C is ideal for a metabolic and bariatric patient to support optimal iron absorption.* 

Food Sources of Iron

There are two forms of iron found in food, heme and non heme iron. Heme iron (readily absorbed by the body) includes:

  • Animal products such as chicken, eggs, ham, pork, salmon, and sardines 

Non heme iron (not as readily absorbed) includes:

  • Plant foods such as spinach, beets, kale, beans, lentils, peas, nuts, and seeds

There are also iron fortified foods available that include breakfast cereals and grains.

Forms of Supplemental Iron*

There are a wide variety of iron supplements to choose from. Below are some recommendations when choosing and iron supplement.*

  • Elemental iron (refers to the total amount of iron that is available in a product to be absorbed by the body).
  • Ferrous fumarate offers the highest percentage of elemental iron, is readily available for absorption and less constipating than other types of iron.* 
  • An iron supplement that contains vitamin C.*

supplemental iron forms


Follow-ups and lab work with your healthcare provider is vital in supporting optimal nutrient levels and overall health.

Bariatric Fusion focuses on the creation of products that are great tasting, affordable, and convenient. Among our various supplement options, we carry chewable multivitamins without iron as well as multivitamins with iron to support differing needs. 

Our multivitamin supplements follow the American Society for Metabolic and Bariatric Surgery (ASMBS) guidelines for nutritional support. Bariatric supplements are recommended for life and should be a bariatric-specific formulation.* 

Individuals who require an additional iron supplement can find products like, iron soft chews with vitamin C. Bariatric Fusion Iron Soft Chews contain 45 mg of elemental iron in the form of ferrous fumarate, so you are receiving a highly bioavailable form along with vitamin C to support absorption.*

Before starting any dietary supplement, it is recommend to consult with your healthcare provider.  

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We think you should consider our next blog Gastric Bypass and Anemia as well.


1. Proc Nutr Soc. 2018; 77(4):445-455 [PMID: 29619914]

2. SOARD. 2020; 16:175-247

3. Blood Adv. 2020; 4(15):3639-3647 [PMID: 32766854]

*These statements have not been evaluated by the Food & Drug Administration (FDA). These products are not intended to diagnose, treat, cure or prevent any disease.

This blog is for information and education purposes only. This information is not intended to substitute professional medical advice, diagnosis, or treatment. Please consult with your bariatric surgeon or another qualified healthcare provider with any questions in regards to a medical condition. A qualified healthcare professional can best assist you in deciding whether a dietary supplement is suitable based on your individual needs.