Uncovering the Links Between IBS and Iron Deficiency - by Jena Volpe, RDN, LD, CLT - Whole-istic Living

IBS and Iron Deficiency: Uncovering the Links

If you’re among the many people worldwide navigating both irritable bowel syndrome (IBS) and iron deficiency, you certainly aren’t alone!  Millions are wondering which came first, how it all started, and what they can do to address their IBS and iron deficiency synergistically.

Being someone who has navigated digestive issues and iron deficiency anemia first-hand, and as a clinician who has worked with over a thousand patients with gut imbalances and/or nutritional deficiencies in my private functional nutrition practice at this point in time, I did some investigating to uncover how and why gut issues and iron deficiency anemia are often correlated and interconnected.

In this article, we’ll unpack all of that! 😎  I’ll also share some of my favorite unconventional but clinically proven ways to manage IBS and iron deficiency anemia together, holistically, from a functional nutrition lens.

Disclaimer: This article is meant to be educational and informative, not to replace medical or nutrition advice! When it comes to health, one size never fits all. Make sure you’re working with a doctor and registered dietitian to receive custom medical nutrition recommendations tailored to your individual needs.

What is IBS?

IBS (“irritable bowel syndrome”) is a chronic, functional digestive disorder in which the way your digestive tract functions isn’t optimal or healthy – but there are no signs or symptoms of an underlying medical condition (i.e. celiac disease, diverticulitis, ulcerative colitis, or Crohn’s disease to name a few).

It’s one thing to have diarrhea, constipation, gas, bloating, heartburn or stomach aches once in a while – it’s another thing to be dealing with that stuff everyday, on-the-reg for what feels like no rhyme or reason!

While no two people with IBS will have the same exact symptoms or food triggers, there are some diagnostic guidelines (aka the “Rome criteria”, developed by an international panel of experts) which doctors often refer back to when determining whether or not you have IBS. (1)

Diagnostic criteria

According to the ROME IV criteria (most recently updated in 2016), you’ve got IBS if you experience recurring abdominal pain at least one day weekly for at least 3 consecutive months, alongside any of the following tendencies for at least 6 months prior to your diagnosis:

  1. Abnormal defecation (bowel movement) patterns.
  2. Abnormal stool frequency (too frequent, or not frequent enough).
  3. Abnormal stool consistency/texture (too hard or too soft).

Signs and symptoms

While everyone is going to have their own variation of IBS, you’ll likely find yourself dealing with at least a few (if not multiple) of the following IBS symptoms at some point along your journey:

  • Abdominal pain or cramping (usually after eating)
  • Bloating 
  • Gas
  • Nausea
  • Constipation (hard-to-pass, and/or painful, and/or incomplete, and/or infrequent bowel movements)
  • Diarrhea (loose, light-colored, too-frequent stools, with or without a feeling of urgency / incontinence)
  • Heartburn / acid reflux 
  • Vomiting (not as common but it can happen!)

Since IBS can manifest differently for everyone, it may also be worth getting familiar with the 3 main subtypes of IBS.

IBS: subtypes

In cases of IBS, you can lean more towards either constipation, diarrhea or a mix of both (i.e. you aren’t having frequent, complete, formed bowel movements but your stools are loose). 

That being said, there are 3 “subtypes” of IBS:

  1. Constipation-predominant IBS (“IBS-C”)
  2. Diarrhea-predominant IBS (“IBS-D”)
  3. Mixed IBS (“IBS-M”)

While IBS can happen to anyone (no matter how healthy you eat), in my professional opinion, IBS still doesn’t just show up out of the woodwork for no rhyme or reason… 

What causes it?

Everyone’s situation is unique to them, and there’s no one cause IBS that anyone has been able to single out.  

On a root-cause level, IBS can be a result of any combination of any of the following factors:

  • Genetics
  • Imbalanced diet
  • Food poisoning
  • Dysbiosis (an imbalance in healthy, probiotic vs. unhealthy, pathogenic gut microbes)
  • Suboptimal gut pH (too acidic or too alkaline relative to what is optimal)
  • Damage to the gut lining – aka “leaky gut syndrome” (usually secondary to any of the following):
    • Alcoholism
    • Drug abuse
    • Stress
    • Mold
    • Candida overgrowth
    • Medication side-effects
    • Antibiotics
    • Birth control
    • Opioids
    • NSAIDs
    • Acid reducers
    • Proton pump inhibitors

The caveat: we “are” what we digest and absorb!

When your gut isn’t working properly, your ability to digest and absorb nutrients from food often will inevitably go downhill – no matter how  “healthy” you eat.

Lots of people with poor digestion left unchecked will eventually end up deficient in certain vitamins and minerals, whether they realize it or not. (Most people actually walk around functioning suboptimally, with a laundry list of nutritional deficiencies, and have no idea!)

But for the purpose of this article, let’s zoom in on iron. 😎

What is iron?

Iron is a mineral which helps our body to make red blood cells. We need a certain amount of iron in the body at any given time, for our blood to carry enough oxygen and nutrition to every cell in the body, 24/7.

Iron deficiency 101

Iron deficiency is a state in which we aren’t getting enough iron from food and supplements, relative to what we need in order to live and function optimally.  Millions of people worldwide are iron deficient, often without even realizing it.  

When iron deficiency is left unchecked over time, it will lead to a condition called iron deficiency anemia which means the size and count of red blood cells are reduced and compromised.

How do you know if you’ve got iron-deficiency anemia?

Aside from the classic signs and symptoms of iron-deficiency anemia (listed in the next section below), anemia is clinically detected and diagnosed when your hemoglobin and hematocrit levels are flagged as low, relative to the established reference range in your Complete Blood Count (CBC) panel.  

  • A CBC panel is considered routine, so your doctor will likely run one of those at least once a year or more.

When your hemoglobin and hematocrit protein levels are low on your CBC, the next step is to look at iron levels, since iron deficiency is the most common form of anemia out there.  

An iron panel blood test will measure each of the following:

  • Iron, Serum
  • Iron Saturation
  • Total Iron Binding Capacity (TIBC)
  • Unsaturated Iron Binding Capacity (UIBC)
  • Ferritin (a storage form of iron contained within the body tissue, to be released and used only for emergency use)

The above lab values will provide your doctor and dietitian with detailed information about the full picture of your body’s overall iron status at a given time, helping them to determine your individualized needs and next steps.

Signs and symptoms

Like IBS, everyone’s iron deficiency anemia symptoms will be unique to them; however, there’s typically a lot of overlap.

Below are the most common signs and symptoms of iron deficiency anemia you may experience when your iron levels drop below normal:

  • Brittle nails
  • Cold intolerance
  • Dizziness/vertigo
  • Fatigue
  • Light-headedness
  • Lower fitness endurance
  • Pale skin and pale nail beds 
  • Poor circulation
  • Restless legs (also seen in anemia from B vitamin deficiencies)
  • Shortness of breath
  • Sore tongue (also often seen in cases of vitamin B12 deficiency)
  • Thinning hair
  • Unusual cravings for ice, clay, dirt, laundry detergent, or other non-food substances 

What causes it?

Based on my first-hand clinical experience and research, iron deficiency most often arises secondary to one or more of the following scenarios:

  • Chronically insufficient dietary iron intake from food/supplements.
  • Pregnancy (since blood volume expands, diluting iron levels).
  • Certain medical conditions (i.e. cancer or kidney disease) which cause the blood to consume and utilize iron faster.
  • Blood loss – usually from heavy menstrual flow, injuries, ulcers, hemorrhoids, and/or anal fissures.
  • Iron malabsorption secondary to low stomach acid levels (aka “hypochlorhydria”) – more on that next!
  • Iron malabsorption due to a chronically inflamed colon, typically caused by irritable bowel disease (IBD).
  • I’ve also observed in my clinic that people with at least one variant of the MTHFR gene mutation are exponentially more prone to having iron-deficiency anemia (and anemia of B vitamins).

Can IBS cause iron deficiency anemia?

Research such as this 2015 JAMA review confirms there’s most definitely a correlation between gut issues and a tendency towards iron deficiency.  

However, in most cases iron deficiency is actually not directly caused by IBS! 

In efforts to demystify this conundrum, as a functional gut health dietitian and holistic-minded clinician, I took it upon myself to dig a little deeper.

Below are two common underlying reasons why and how certain types of gut issues (but not usually IBS) often contribute to iron-deficiency anemia at a root-cause level.

Hypochlorhydria, IBS, and iron deficiency

Hypochlorhydria (low stomach acid) is a common gut issue, and it doesn’t ever *just* happen for no reason! 

Acid-altering medications

Too-low stomach acid levels are a silent epidemic. This scenario most of results from taking acid-reducing medications (like  Prilosec/Omeprazole, Nexium, Protonix/Pantoprazole, Pepcid/Famotidine, Zantac/Ranitidine, or Tums, to name a few examples) for too long.

  • These medications really aren’t meant to be taken long-term.  (The recommended “cut-off” time to stop taking them, according to warning labels, is only 14 consecutive days!) 
  • However, in the conventional healthcare system, I’ve seen most doctors put their patients on acid-reducing medications indefinitely, without any break or follow-up.

Age and stomach acid

Stomach acid levels also naturally decline with age, so older adults may find their gut isn’t digesting foods the way it used to.  (This is why many older adults start needing B12 injections which serve to bypass the gut, so B12 can go directly into the bloodstream!)

Co-morbidities (aka “collateral damage”) from low stomach acid

From a functional medicine perspective, I’ve seen “Domino effects” from long-term hypochloridia such as gut imbalances (like IBS and dysbiosis) as well as micronutrient deficiencies (including iron deficiency), which can all spiral into even bigger problems. 

  • This is because a too-alkaline (low-acid) gut pH allows for certain “bad” pathogenic microbes to overgrow out of control.
  • A gut at a too-high pH (not acidic enough) will also impair your body’s natural ability to absorb certain key vitamins and minerals like B12, zinc, calcium, magnesium and iron to name a few.

Long story short, hypochlorhydria is one of two main ways that gut imbalances left unchecked can lead to poor iron absorption and subsequently iron-deficiency anemia over time.

IBS vs IBD and iron deficiency

There’s a LOT of overlap between IBS and IBD symptoms – which is why IBD typically flies under the radar for too long.  In my clinic, having worked with over a thousand clients navigating gut issues at this point in time, I’ve come to realize most doctors unfortunately don’t leave no stone unturned  before hastily slapping the ‘IBS’’ diagnosis’ on a patient’s medical record.

And to make matters worse, most patients experiencing generalized GI symptoms like abdominal pain and/or diarrhea don’t usually know which tests to ask for when they go to a doctor.  They assume doctors will automatically get tested for “everything” which, 95% of the time, is not the case!

In my clinic, I’ve found that an estimated 10 to 15% of people presenting with what looks like IBS on the surface-level actually have an underlying IBD condition such as:

  • Celiac disease
  • Crohn’s disease
  • Diverticulitis
  • Ulcerative colitis

All of that said, it’s exponentially more likely for IBD versus IBS to cause iron-deficiency anemia.

So, does IBS cause anemia? The final verdict

While IBS doesn’t directly cause iron deficiency anemia, low stomach acid and undiagnosed IBD masking as IBS seem to be the top two common denominators when IBS symptoms precede iron deficiency anemia.

If either or both of those gut imbalances apply to you, addressing your gut issues at the root-cause level will be necessary and imperative (alongside iron repletion) in order for you to resolve your iron deficiency anemia long-term!

Can iron deficiency cause IBS?

At this point in time, we have no reason to believe that iron deficiency inherently plays any direct role in causing or contributing to IBS.

However, it’s important to note that clinical iron supplementation (when taking it synthetically as ferrous sulfate) often wreaks havoc on the gut! 

Ferrous sulfate supplementation for anemia (independent of dose) has been linked with causing and amplifying  gut issues such as constipation, nausea, diarrhea, dysbiosis, and in some extreme cases, even an ileus (atrophy of the gut). (2, 3)

Can iron deficiency anemia cause diarrhea?

While iron deficiency in and of itself won’t cause diarrhea, and iron supplements (specifically in the form of ferrous sulfate) are more likely to cause constipation and nausea, it’s still possible for iron supplements to cause diarrhea among some people. (2)

Iron supplements and IBS

Iron supplements for anemia are like a double-edged sword.  While it’s sometimes necessary to take ferrous sulfate to treat iron-deficiency anemia more aggressively, taking synthetic iron supplements usually isn’t without consequence – especially for those of us with IBS.

Ferrous sulfate and the gut – what you should know

Ferrous sulfate (whether in liquid or pill form) is currently the “gold standard” for iron supplementation in the clinical world, because it will boost iron levels fast – without iron infusions which are more invasive, expensive and time-consuming. However, there’s a dark side to supplementing with iron in this form.

This form of iron (when taken orally as a supplement) is notorious for causing constipation as well as nausea and sometimes abdominal pain or diarrhea among most people, even including those with an “iron” stomach (pun intended). (2)

Below are a few key things to keep in mind when taking iron supplements as ferrous sulfate, in order to minimize any potential adverse reactions and avoid the likelihood of an IBS flare as much as possible.

  1. Never self-prescribe iron supplements!  Make sure to take iron pills only as prescribed by a doctor, since taking them unnecessarily can actually cause significant liver damage.
  2. Take iron supplements with vitamin C-rich orange juice or fruit for optimal absorption.  Vitamin C helps convert non-heme iron to heme, which is the form that our body uses to make red blood cells.
  3. Don’t take iron within a few hours of calcium-rich foods or supplements.  (This includes milk, calcium-fortified dairy alternatives, yogurt, etc.)  This is because calcium and iron compete for the same absorption sites through your gut, into your bloodstream.
  4. Take your iron supplement (as prescribed) with a meal versus on an empty stomach, to avoid nausea.

If you’re already prone to IBS-C or IBS-M, you may also want to talk to your doctor, registered dietitian and possibly also consult an acupuncturist or western clinical herbalist about alternative ways to boost iron without supplements, if that is a clinically safe option.

Managing iron deficiency with IBS

Step 1: Replete iron levels

Don’t get me wrong – sometimes it’s 110% necessary to take iron supplements or even receive iron transfusions/blood transfusions to correct an extreme iron deficiency, clinically.  

Iron infusions vs. iron supplements: pros and cons

If you find that the prescribed iron supplements do aggravate or exacerbate your gut issues, I think it’s worth asking your doctor about the possibility of iron infusions, which bypass the gut. They are less convenient and more expensive, but could be worth it.

Boosting iron levels naturally

On the other hand, in less severe cases of iron deficiency anemia, what most people don’t realize is we can actually optimize iron levels naturally via partnering with the right foods, herbal teas, herbal iron syrups, and/or even certain cooking methods (such as using a cast-iron skillet).

The best way to boost iron levels fast from a dietary standpoint is to consume plenty of iron-rich foods and herbs. Below are some of the most iron-rich dietary sources of iron from both plants and animal sources:

Food sources of heme iron

Getting iron from animal food sources is advantageous for those of us with iron deficiency anemia, because this form of iron is the active form, “heme”, which is the kind that our body uses and absorbs best.

  • Organ meat (i.e. liver pate)
    • 1 oz. liver pate = 1.56 milligrams of iron (4)
  • Beef (ideally 100% grass-fed)
  • Bison
  • Elk
  • Mussels 
    • 3 oz. cooked = 5.7 milligrams of iron (5)
  • Oysters
    • 6 medium oysters = 6.12 milligrams of iron (6)
  • Venison

It’s important to keep in mind that eating lots of meat on a regular basis is not healthy for some people (especially those with high cholesterol or gout).  That’s where plant-based iron-rich foods and herbs can come in handy!

Plant-based iron-boosting foods and herbs

Plant–based food sources of iron are non-heme, so iron from plants will need to be combined with vitamin C in order to convert into heme iron. 

While the exact mechanism is unknown, certain herbs anecdotally also have an iron-boosting effect clinically without directly providing a dietary source of iron. 

Below is a list of my top favorite iron-boosting foods and herbs, speaking as a dietitian and herbalist!

  • Alfalfa sprouts or powder (Medicago sativa) (7)
  • Beet roots and beet greens (freshly juiced, or cooked)
  • Blackstrap molasses
  • Cacao powder (Theobroma cacao)
  • Dandelion leaf and root (Taraxacum officinale)
  • Leafy greens
  • Lentils and beans
  • Moringa powder (Moringa oleifera) (8)
  • Parsley (Petroselinum crispum)
  • Stinging nettle leaf (Urtica dioica)
  • Yellow dock root (Rumex crispus
Herbal iron syrup

Some people with IBS-C or IBS-M find they do well with an herbal iron syrup, which won’t cause constipation.  

  • However, in some cases I’ve actually seen this cause diarrhea, since yellow dock tends to stimulate the lower GI tract!
  • Also, herbal syrups generally contain honey, which is high in fructose and thus high FODMAP. 
    • If you’ve got a fructose intolerance or you suspect you’ve got small intestinal bacterial overgrowth (SIBO), make sure to check for honey or other high-fructose ingredients in herbal iron syrups before diving into herbal iron syrup (no matter how tasty it is!).
Cast-iron cookware

An unconventional but effective way to boost iron intake holistically is to cook acidic foods (such as tomatoes) in cast-iron cookware. (9, 10)  

While more research would be great to further investigate, this intervention can help and it can’t hurt (provided your cast-iron cookware is properly seasoned and clean). 😉

Cast-iron cookware is especially useful as an intervention for people with iron deficiency in developing countries, with limited access to food, supplements and adequate medical care.

No matter where in the world you live, or what type of healthcare and food you have access to, I encourage you to give this one a try and see how it goes over time!

Step 2:  Get clear on your root cause(s) 

While treating iron deficiency anemia is urgent and very important, it’s also critical that you investigate your gut issues and any other possible underlying causes of your anemia at the root-cause level. 

Whether it’s low stomach acid or IBD or something totally different, remember things don’t just happen for no reason! (We spend an entire two weeks just connecting symptoms to diagnoses and root-causes in Module 1: Clarity in my Complete Gut Repair Roadmap online program!)

It may feel daunting – but if you don’t address your conditions from the level at which they first began, those issues may never go away, and things could get worse or spiral into other problems if left unchecked.

You should not try to navigate this on your own!  There are people out there who can and want to help you.  

  • Make sure to get the support you need by working with formally trained, licensed and qualified holistic-minded practitioners who specialize in what you need. 

Please also feel free to check out the additional resources and takeaways below if you’d like to learn more about supporting and managing iron deficiency and IBS from a holistic, functional nutrition and herbal medicine standpoint.

Additional resources for IBS & gut health

Additional resources for iron deficiency anemia

Takeaways and next steps

Millions of people worldwide are struggling with both IBS and iron deficiency anemia, and people are looking for answers and solutions that go beyond the surface level.

While the two conditions go hand-in-hand, iron supplementation is more likely to trigger an IBS flare or trigger acute-onset digestive discomfort than to cause IBS as a stand-alone factor.

While IBS isn’t usually a culprit of iron deficiency anemia, other gut imbalances and disorders such as hypochloridia (low stomach acid) and/or IBD are more likely to impair iron absorption in the gut, leading to nutritional deficiencies (including iron deficiency) over time.

If you’re finding you eat relatively “normal” healthy amounts of iron from iron-rich foods like red meat and leafy greens, and you aren’t pregnant, and you don’t have cancer or kidney problems, and you haven’t experienced any blood loss, and you’ve got symptoms that appear to be IBS, you should most definitely ask your treatment team to help you rule out IBD!

If you’ve got a severe iron deficiency and you’re also prone to IBS, iron infusions (while a bit more invasive and less convenient) may be a good alternative to synthetic iron supplements because they bypass the gut and keep you clinically stable.

On the other hand, if you’re in the early stages of navigating a more mild case of iron deficiency anemia, incorporating an herbal iron syrup or other iron-rich foods and herbs into your regimen can go a very long way! 

Cooking acidic foods in a cast-iron skillet is another unconventional but very effective way to boost iron levels in certain foods.

Remember – you know your body better than anyone else.  If something feels off, it’s important for you to be your own advocate and leave no stone unturned until you feel realigned.

If you’re feeling stuck/overwhelmed, and you’d love step-by-step guidance on how to crack your Gut Code from a clinical and holistic standpoint, I highly recommend checking out and enrolling in my signature program, the Complete Gut Repair Roadmap!