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Can Low Iron Cause Digestive Issues? Iron Deficiency Basics

Written by Dr. Michael Ruscio, DC on April 20, 2022

Written by Dr. Michael Ruscio, DC on April 20, 2022 — Reviewed by Aimee Gallo

The Connection Between Gut Disorders and Low Iron Levels 

• Can Low Iron Levels Cause Digestive Issues?|
• Common Causes of Low Iron|
• Iron Deficiency Anemia|
• Iron Supplements and the Gut|
• How to Increase Iron Levels|
• Final Thoughts|

Many people who take iron supplements know that they can come with side effects of nausea, stomach pain, and constipation. But can low iron cause digestive issues, as well? 

While low iron likely doesn’t directly cause GI distress, many functional gut disorders and digestive conditions coexist with an iron deficiency. However, it’s likely that digestive system imbalances are actually coming first and contributing to iron deficiency (not the other way around). 

Inflammation, low stomach acid, GI bleeding, autoimmunity, and bacterial overgrowth in the GI tract can all lead to decreased levels of vitamins and minerals in the body, including iron. 

These conditions commonly present with digestive complaints like, reflux, gas and bloating, stool changes, and abdominal pain. However, these symptoms are likely a manifestation of an underlying digestive condition, rather than low iron levels. 

When optimizing iron status in the body, it is important to uncover and address the root cause of your symptoms first, in order to maximize nutrient absorption in the gut. This is especially true for those already struggling with gut disorders. 

This article will take a closer look at the relationship between low iron levels and poor gut health. It will help you recognize some of the signs that you may be dealing with an iron deficiency and how to address it, in part by healing your gut. 

Can Low Iron Cause Digestive Issues?

It is not uncommon for an iron deficiency to present alongside uncomfortable gut symptoms like gas and bloating, constipation, diarrhea, and abdominal pain. And while there is no evidence that supports that low iron levels directly cause GI symptoms, iron deficiency can often result from digestive disorders. 

Some common causes of iron deficiency can be broken down into four main categories:

1. Lack of dietary iron: Improper nutrition, a copper deficiency, eating disorders, and a vegan or vegetarian diet 1
2. Decreased gut absorption: GI inflammation, irritable bowel syndrome (IBS), gut infections, a bacterial imbalance, certain medications, low stomach acid, and gastric bypass surgery 2 3
3. Altered iron utilization: Pregnancy, chronic infections, autoimmunity, heart failure, and cancer 1 2
4. Increased blood loss: Inflammatory bowel disease (IBD), peptic ulcers, intestinal polyps, heavy menstruation, and other bleeding disorders 1 3

Low iron levels that result from digestive disorders primarily fall under the categories of decreased absorption and increased blood loss in the gut. These faulty digestive processes can accompany a wide array of GI conditions and functional gut disorders. Let’s look at a few of the more prevalent causes of decreased iron absorption that we see in the clinic.

Digestive Causes of Low Iron Levels

Iron deficiency is most prevalent in women, due to blood loss during the menstrual cycle, and is fairly uncommon amongst the male population. However, both men and women alike can suffer from low iron levels if poor gut health is to blame. The following digestive disorders are some of the more common reasons that we see a decline in the body’s iron stores. 

Low Stomach Acid

Many factors, such as chronic gastritis, H. pylori infection, or use of certain medications can decrease your stomach acid levels. Regardless of the cause, we often see that malabsorption of nutrients and minerals (including iron) is due to low gastric acid in the stomach. 

Iron absorption directly requires stomach acid in order to be absorbed in the gut 4. Low stomach acid, or hypochlorhydria, not only prevents this from happening, but can lead to pathogens or a bacterial overgrowth in the gut, which further decreases iron absorption 5 6 7 8.

Low stomach acid is also associated with autoimmunity, particularly autoimmune atrophic gastritis, where antibodies attack the cells that help produce acid in the stomach 9.

Gastritis is especially tricky when it comes to low iron levels, as it both increases inflammation and decreases stomach acid production. Along with decreased iron levels, it often creates symptoms of 10:

• Abdominal pain
• Gas, bloating, and excessive burping
• Reflux and heartburn
• An excessive feeling of fullness post-meals
• Nausea and/or vomiting

Autoimmunity aside, there are other causes that break down the protective lining of the stomach and decrease stomach acid levels. 

Aging is one major contributing factor to atrophic gastritis 11, and up to a third of the general population has chronic atrophic gastritis. However, research shows that it is most prevalent in adults aged 35-44 12, meaning that there are likely other factors at play, other than age, in the development of chronic gastritis.

Low acid levels aren’t always due to an underlying medical condition. In fact, one of the most frequent causes of deficient stomach acid is chronic use of heartburn and gastroesophageal disease (GERD) medications. Antacids, acid-blockers, and proton-pump inhibitors are all intended to decrease stomach acid levels and can result in an iron deficiency 1.

Intestinal Inflammation

Chronic inflammation in the gut can damage the lining of the gastrointestinal tract 9, resulting in poor iron absorption in the duodenum of the small intestine. Intestinal inflammation can be due to a variety of disorders, including 1:

• Celiac disease and autoimmune gastritis
• Irritable bowel syndrome (IBS)
• Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)
• Small intestine bacterial overgrowth (SIBO)
• H. pylori infection
• Non-autoimmune atrophic gastritis

Leaky gut syndrome can arise from chronic GI issues, and is distinguished by an increase in intestinal permeability. In other words, it is a weakening of the barrier that lines the GI tract. As the cells in the gut begin to loosen and separate, it allows for foreign molecules to enter the blood, creating an immune response 13.

This immune response can create significant inflammation in the small intestine that prevents the proper absorption of iron.

Inflammatory bowel disease (IBD) is another common cause of low iron levels 1. IBD is categorized by the presence of Crohn’s disease and/or ulcerative colitis, both of which significantly increase inflammation in the digestive tract and can cause gastrointestinal bleeding. When gut inflammation and blood loss present together, they often lead to iron deficiency anemia.

As you can see, it’s important to understand the cause of your iron deficiency in order to properly treat your digestive symptoms and increase your iron levels. Fortunately, there are simple and straightforward steps that can effectively improve your gut health, regardless of the specific issue.

What Is Iron Deficiency Anemia?

Anemia is considered to be a lack of red blood cells in the body. When the body doesn’t have enough iron, it cannot make hemoglobin — the protein that helps carry oxygen in the blood 14. Folate or a vitamin b12 deficiency can also cause anemia, as can some chronic diseases and medications 1 4 5 15.

Some common signs that you aren’t getting enough iron, and have possibly developed anemia, include 1 14:

• Dizziness and fainting
• Paleness (occurs in severe cases) 14
• Shortness of breath
• Weakness and fatigue
• Headaches
• Ice cravings and pica (eating non-edible items)
• Chest pain and rapid heart rate
• Hair loss

Keep in mind that not all people who have an iron deficiency are anemic, and may not present with the above symptoms. Anemia occurs in the late stages of iron deficiency, when there is a drop in hemoglobin levels 1.

While low iron may not directly lead to digestive issues, iron deficiency alone can still create many uncomfortable symptoms. If you still suspect your symptoms are due to a lack of iron, or even iron-deficiency anemia, what’s next?

Diagnosing an Iron Deficiency

There are different types of anemia, so it is important to undergo a proper diagnostic workup when evaluating the cause of your anemia. Blood tests that measure your complete blood count, nutrient levels, and inflammatory markers can all reveal the underlying cause.

In the case of iron deficiency anemia, the following labs can be used for a diagnosis 2:

• Serum iron levels
• Ferritin (the storage form of iron)
• Total iron binding capacity (TIBC)
• Transferrin saturation

If upper GI disorders, including gastritis and peptic ulcers, are the culprit of your low iron stores, they can be diagnosed via endoscopy (a scope that looks into your esophagus and stomach). Digestive conditions that affect the lower GI tract, like IBD, are often discovered with a colonoscopy and blood tests that look for certain antibodies 14.

As previously discussed, iron deficiency can often result from long-term use of antacids, acid blockers, and PPIs. Even antibiotics and medications for hypothyroidism, Parkinson’s, and osteoporosis can lead to iron deficiency anemia 1.

Fortunately, iron deficiency anemia often has a good outcome and may easily be treated with oral iron supplements. However, if left alone, iron deficiency can lead to serious health complications 1.

Iron Supplements Can Cause Gut Symptoms

While iron supplements can easily treat iron deficiency anemia, they can cause issues of their own. Iron supplements often trigger symptoms of 2:

• Nausea
• Abdominal cramping or pain
• Diarrhea
• Constipation

Iron supplements may increase inflammation in the GI tract, as well. However, this only appears to occur when there is already an imbalance in the gut microbiota or if gut pathogens are present 16 17. This is another reason why it’s important to focus on improving your gut health either before or while optimizing your iron levels.

Despite these issues, there are some forms of supplemental iron that seem to be a little easier on the gut. Ferrous gluconate (liquid iron) appears to cause the least amount of GI upset, as do chelated forms, like ferrous bisglycinate. The following are three popular forms of iron supplements:

• Ferrous sulfate: This form is inexpensive and easy to find, but is probably not as well-absorbed in the gut and may have more GI side effects 18.
• Ferrous gluconate: This form is commonly given in liquid form, is more easily absorbed, and is not as hard on the gut. However, it contains less elemental iron and may need to be given in higher doses for a therapeutic effect 18.
• Ferrous bisglycinate: This is a chelated form of iron, meaning it is bound to an uncharged molecule that helps transport it through the GI tract. Chelated forms of iron may come with fewer digestive side effects 1.

Iron supplements are contraindicated in some conditions, such as hemochromatosis (a genetic cause of iron overload), which primarily affects men 18. In select cases, it may be best for women who have polycystic ovary syndrome (PCOS) to avoid iron supplementation 19. In severe, but uncommon, instances, excess intake of iron supplements can lead to vomiting, liver injury, and other organ damage 20.

For these reasons it is important to speak with your health care practitioner and have your iron levels checked before starting iron supplements.

Other Ways to Increase Iron Levels (And Heal the Gut)

If you have low iron levels and are unresponsive to iron supplements, cannot tolerate the side effects, or simply are interested in other ways to increase your iron levels, read on for tips on how to increase your iron. 

1. Increase dietary iron: Certain iron-rich foods like red meat, spinach, and fortified cereals can help raise iron levels. Additionally, consuming vitamin C along with iron-containing foods may increase iron absorption in the gut.

However, one study found that vitamin C intake, alongside iron supplementation, had no effect on iron absorption 21. Additionally, excessive use of vitamin C supplements can lead to diarrhea, causing poor absorption of iron-rich food or oral supplements.

2. Asses for low copper levels: Recent research suggests that a copper deficiency may be at the root of low iron levels. Copper and iron metabolism have a close-knit relationship, and a deficiency in one of these minerals may alter levels of the other 22.

Consider optimizing your copper levels, under the guidance of a functional medicine practitioner, when increasing your iron levels.

3. Increase stomach acid: If low stomach acid is at the root of your low iron, betaine hcl can increase iron absorption. Betaine hcl should be taken right at the start of meals and never on an empty stomach 23 24. You should not take this supplement if you have been diagnosed with peptic ulcers or if you feel a burning sensation upon ingesting it.

4. Reduce gut inflammation: An elimination diet, like the Paleo diet, which removes common food triggers can help resolve intestinal inflammation. If you see no improvement in your symptoms in 3-4 weeks, it may be time to move on to a more specialized diet, such as the low-FODMAP diet, that can address an underlying imbalance in the gut flora.

Probiotic therapy is also highly effective at reducing chronic inflammation in the gut and increasing nutrient absorption 25. We recommend using three different categories of high-quality probiotics for the best results. Please see our probiotics starter guide for more information on how to implement probiotic therapy.

5. Intravenous (IV) iron: This form of iron is delivered directly into the blood through an IV, and must be done under the supervision of a physician. It is an FDA-approved method for treating iron deficiency anemia in those who cannot tolerate or do not respond to oral iron 2. By bypassing the GI tract, it avoids the digestive side effects of oral iron and can rapidly replete iron stores in the body, as its absorption isn’t dependent on gut health.

While these recommendations can all help restore normal iron levels in the body, we frequently see in practice that it’s more effective to address any underlying gut conditions prior to optimizing nutrient status. If the root cause of malabsorption is not resolved, there may be an undesirable response to iron supplementation.

Can Low Iron Cause Digestive Issues? Probably Not 

While digestive disorders that lead to low stomach acid, intestinal inflammation, and bleeding in the GI tract can decrease iron in the body, low iron levels do not appear to directly cause GI distress. 

Those who are diagnosed with an iron deficiency and are taking supplemental iron may also experience GI side effects. Fortunately, there are several forms of iron that are less harsh on the digestive tract and can help correct an iron deficiency. 

It is important to treat the root cause of your iron deficiency and heal any underlying gut conditions prior to optimizing your iron and other nutrient levels. If you are seeking help for symptoms of iron deficiency, a digestive disorder, or any other health concern, reach out to us at our functional medicine clinic. 

You can also check out my book, Healthy Gut, Healthy You, for more advice on how to heal your gut and start feeling better. 

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.