Low Iron That Won’t Improve?
Low iron is one of the most common issues I see in the pharmacy.
Many people pick up an iron supplement over the counter, hoping it will lift their energy. Sometimes it does. But often, the story is more complex than "I'm low, so I need more iron."
Why Ferritin Alone Isn't Enough
Quite often, ferritin is the only iron test that's ordered. I prefer to look at the full iron panel, because each marker tells us something different.
Here's a simple way to picture it:
Ferritin is your savings account, the iron stored away for later.
Transferrin is the fleet of delivery trucks that carry iron around your body.
Transferrin saturation is how full those trucks are.
Serum iron is the iron on the road right now.
Saturation, in particular, can give us a much clearer picture of what may be driving low ferritin.
Ferritin also rises with inflammation. So someone can look "fine" on ferritin while actually running low. Looking at the whole panel, alongside red blood cells, shows how things are truly tracking.
Why More Iron Isn't Always the Answer
When iron is low, the usual approach is more supplements, and if those don't work, an iron infusion. Infusions can work wonderfully well. Some people feel significantly better afterwards.
But not everyone does. Some feel worse, some have reactions, and in some, iron can build up to unsafe levels over time, which is why monitoring matters.
My preference is to ask a different question first: why is the iron low?
Looking for the Cause
From what I see in clinic, the cause is often one, or several, of these:
not enough iron-rich foods
poor absorption through the gut
gut dysbiosis, where some microbes may compete for iron, which can show up on microbiome testing
inflammation, which raises a hormone called hepcidin and locks iron away in storage
liver health, since the liver makes the proteins that package and transport iron
missing cofactors such as B12, vitamin C, magnesium, and a healthy copper and zinc balance
ongoing blood loss
gluten intolerance or coeliac disease
Some people have iron tablets or infusions regularly, yet their levels barely move. In these cases, the iron may be there but not being used, because the body is missing something else entirely.
The Gluten Connection
This is one I rarely see mentioned, yet I believe it can be a major contributor.
Iron is absorbed mainly in the first part of your small intestine. The lining there is covered in microvilli, which are thousands of tiny finger-like projections. I like to picture them as tiny fishing nets, catching nutrients as food passes by.
In coeliac disease, an autoimmune reaction to gluten damages those nets. They wear thin and flatten, so iron, along with many other nutrients, slips straight through, no matter how much you eat or take.
Gluten intolerance, without coeliac disease, can also show up as bloating, gas and fatigue, and in my experience it can affect iron status too.
Testing Matters
Coeliac disease can be assessed with a genetic blood test, which can rule it out, or with a blood test for transglutaminase antibodies (tTG-IgA). For the antibody test to be accurate, you need to be eating gluten every day, usually for around six weeks beforehand. Going gluten-free before testing can hide the result.
Another test done in Functional or Integrative Medicine that can give more insights into gut function is called Microbiome mapping, it can also help reveal gluten intolerance and dysbiosis. It is particularly useful when a colonoscopy hasn’t shown any discrepancies because it is able to identify markers of inflammation, dysbiosis, and opportunistic pathogens that are invisible to a scope.
What I've Seen in Clinic
Many times, I've found gluten intolerance or dysbiosis on a client's microbiome mapping. Once we removed gluten and supported their gut, their iron levels began to improve.
It's rarely the only factor. But it's often an important piece that had been missed.
Getting More From Iron Supplements
As a pharmacist, I wish more people knew that not all iron supplements are made equal.
Some common forms can cause constipation and gut irritation. If that's been your experience, iron bisglycinate is often gentler and well absorbed.
Studies also suggest that taking iron every second day, rather than daily, can improve absorption. This is because a dose of iron raises hepcidin for around a day, which reduces how much of the next dose gets in.
Taking iron with its cofactors, such as vitamin C, makes a real difference too.
The Deeper Pattern
Over the years, I've noticed that many individuals with low iron are giving too much, physically or emotionally. They're doing more than their body can replenish.
Physically, this is well recognised. Intense exercise and heavy sweating can deplete iron.
Traditional Chinese Medicine sees it emotionally too. Blood is understood as deeply nourishing, built from food by the Spleen, and it can become depleted through overwork, worry and constantly giving to others.
So part of rebuilding iron may be learning to receive and replenish, as well as give.
Three First Steps
If you suspect low iron, here's where I'd start:
Get a full iron panel and blood count. Remember, too much iron can cause the same tiredness as too little, so test before you supplement.
Choose a well-absorbed form, such as iron bisglycinate, taken every second day with cofactors.
See an integrative practitioner to look for other related mineral and vitamin deficiencies, gut health and possible food intolerances, including gluten.
When to See Your GP
The cause of iron loss should always be checked by your doctor first. For women, heavy or irregular periods are a common reason. For others, regular anti-inflammatory use (NSAIDs) or a small, ongoing blood loss from the gut can be responsible.
This is especially important for men and post-menopausal women with low iron, where a medical investigation is always recommended.
Please also see your doctor promptly if you notice blood in your stools, black or tarry stools, shortness of breath, chest pain, or a racing heart.
Getting to the Root, Rather Than Just Topping Up
Low iron is common, but it doesn't have to be a cycle of tablets and infusions that never quite stick.
When we look for the cause rather than simply topping up, the body often has a much better chance of holding on to what it needs.
If your iron levels have been stubborn, I'd love to help you explore why. You're welcome to book a free discovery call, and we can look at your bloods, gut health and the bigger picture together.
Rosemary Bui
Integrative Pharmacist and Holistic Health Strategist