You’re doing all the right things — taking your iron supplements every day, eating well, maybe even adding more leafy greens to your meals. But despite all that effort, you still feel constantly tired, foggy, or short of breath. And your blood tests? Still showing low iron.

Iron deficiency is one of the most common nutrient deficiencies worldwide — but what many people don’t realise is that low iron levels aren’t always due to not getting enough iron. Sometimes, it’s about how well your body can actually absorb the iron you’re giving it.

Iron absorption is a delicate process influenced by everything from your gut health to the timing of your supplements. Even what you eat (or drink) alongside your iron tablet can make a big difference. In this blog, we’ll unpack the reasons your body might not be absorbing iron effectively, the common mistakes people make, and what you can do to improve your iron levels — and feel like yourself again.

How iron is normally absorbed in the body

To understand why your iron supplements might not be working, it helps to first know how iron is absorbed by the body.

Iron is an essential mineral that helps your body make haemoglobin, the protein in red blood cells that carries oxygen throughout your body. But before it can do any of that, it needs to be absorbed through your digestive system, primarily in the small intestine — specifically, the duodenum and upper jejunum.

Two types of iron: Heme vs non-heme

Iron comes in two dietary forms, and your body absorbs each type differently:

• Heme iron:
  Found only in animal-based foods (like red meat, poultry, and fish), heme iron is the most easily absorbed form. The body absorbs up to 15–35% of heme iron.
  

• Non-heme iron:
  Found in plant-based foods (like lentils, spinach, and fortified cereals) and most iron supplements, non-heme iron is less efficiently absorbed, with an absorption rate closer to 2–20%.

Most iron supplements on the market — including ferrous sulfate and ferrous fumarate — use non-heme iron, which requires more favourable conditions in the digestive tract to be properly absorbed.

Stomach acid plays a big role

For iron to be absorbed efficiently, especially non-heme iron, it must be converted into a soluble form. That’s where stomach acid (hydrochloric acid) comes in. It helps break iron down into a form that the intestinal lining can take in. If your stomach acid levels are too low — a condition known as hypochlorhydria — your body may struggle to absorb iron, even if you’re taking plenty of it.

Low stomach acid can be more common than people think. It’s often linked to:

• Ageing
  

• Frequent use of acid blockers (like PPIs or antacids)
  

• Chronic stress
  

• Certain medical conditions

How the body regulates iron absorption

Unlike many nutrients, your body doesn’t have a dedicated mechanism to excrete excess iron. Instead, it relies on a regulatory system to adjust how much iron it absorbs based on your current needs.

This regulation is managed by a hormone called hepcidin, which controls iron absorption by:

• Blocking iron transport when levels are high
  

• Increasing absorption when levels are low

However, inflammation or chronic illness can disrupt this balance. For example, people with chronic inflammation or infections may produce too much hepcidin, preventing iron absorption even when their iron levels are low — a condition known as anaemia of chronic disease.

Iron transport and storage

Once absorbed, iron doesn’t just float around in your bloodstream. It binds to a protein called transferrin, which carries it to the bone marrow (for red blood cell production), liver (for storage), or muscles (for oxygen use).

If there’s a breakdown anywhere in this chain — whether in absorption, transport, or storage — it can lead to iron deficiency symptoms, despite regular supplementation.

Common reasons iron supplements aren’t being absorbed

If you're taking iron supplements but your iron levels remain low, it's not necessarily about how much you're taking — it's about how well your body is absorbing it. There are several factors that can interfere with absorption.

1. Low stomach acid (Hypochlorhydria)

Iron needs an acidic environment to be converted into a form that the small intestine can absorb — and this is especially true for non-heme iron, the type found in most supplements. If your stomach acid levels are too low, iron may pass through your digestive system without being properly absorbed.

Common causes of low stomach acid include:

• Ageing (acid production tends to decline with age)
  

• Long-term use of antacids or proton pump inhibitors (PPIs)
  

• Chronic stress
  

• Certain autoimmune conditions

People with low stomach acid may also experience bloating, indigestion, or reflux, but ironically, these symptoms are often mistaken for too much acid rather than too little.

 2. Taking iron with the wrong foods or drinks

Certain foods and beverages can significantly inhibit iron absorption, especially if taken within an hour of your supplement.

Things that interfere with absorption:

• Calcium-rich foods or supplements (milk, cheese, yoghurt, antacids)
  

• Tea and coffee (contain polyphenols and tannins)
  

• High-fibre foods (especially unprocessed bran or whole grains)
  

• Phytates found in legumes, nuts, and seeds

Even something as simple as a morning latte or a calcium-fortified breakfast cereal can reduce the effectiveness of your iron supplement if taken at the same time.

 3. Gastrointestinal conditions

Several medical conditions can impair your gut’s ability to absorb iron, even if you're taking the correct dose and form.

Examples include:

• Coeliac disease – damage to the intestinal lining makes it harder to absorb nutrients like iron.
  

• Inflammatory bowel disease (IBD) – conditions like Crohn’s or ulcerative colitis cause inflammation and reduce nutrient uptake.
  

• Irritable bowel syndrome (IBS) – while not an inflammatory disease, it may still interfere with absorption in some individuals.
  

• History of gastric bypass or bowel surgery – parts of the intestine responsible for iron uptake may be removed or bypassed.

In these cases, oral supplementation might not be enough, and iron infusions may be necessary.

 4. Wrong form or dose of iron supplement

Not all iron supplements are created equal. Some forms of iron are more easily absorbed — and better tolerated — than others.

Common forms of iron supplements:

• Ferrous sulfate – widely used, inexpensive, but can cause constipation and nausea.
  

• Ferrous gluconate or fumarate – gentler alternatives, but still poorly tolerated by some.
  

• Liposomal or liquid iron – newer forms that may offer better absorption and fewer side effects.

If you’re not responding to your current supplement, switching to a different formulation might make a difference — especially if gastrointestinal side effects are making it hard to stay consistent.

5. Not enough vitamin C

Vitamin C (ascorbic acid) plays a crucial role in iron absorption by converting ferric iron (Fe3+) to ferrous iron (Fe2+), which is more absorbable.

How to fix this:

Taking your iron supplement with a glass of orange juice or alongside foods high in vitamin C — like capsicum, kiwi fruit, broccoli, or strawberries — can significantly boost absorption.

On the flip side, taking it with dairy or calcium supplements can do the opposite.

6. Poor gut health or microbiome imbalance

Emerging research suggests that your gut microbiota — the trillions of bacteria living in your digestive tract — play a role in how your body absorbs and metabolises nutrients, including iron.

An imbalance (or dysbiosis) in the gut may lead to:

• Inflammation that interferes with nutrient absorption
  

• Overgrowth of bacteria that compete for iron
  

• Weakened gut lining (“leaky gut”), making it harder for iron to cross into the bloodstream

Improving gut health through a balanced diet, prebiotics, probiotics, and limiting inflammatory foods may support better nutrient absorption overall.

7. Hormonal and genetic factors

In some cases, low iron absorption is influenced by hormones or genetic conditions. For example:

• People with chronic inflammation may produce excess hepcidin, a hormone that reduces iron absorption.
  

• Certain rare genetic conditions (e.g. iron-refractory iron deficiency anaemia) affect the body’s ability to utilise iron.

These scenarios require medical attention and may need specialist treatment beyond standard supplementation.

Symptoms that may signal iron isn’t being absorbed

If you've been diligently taking iron supplements but still don’t feel better — or your blood tests keep coming back low — it might be time to take a closer look at your symptoms. When the body isn’t properly absorbing iron, it can’t produce enough healthy red blood cells, leading to iron deficiency anaemia or persistent low iron stores (low ferritin).

Here are the most common signs your body might not be absorbing iron effectively — and what they may be trying to tell you.

1. Ongoing fatigue and weakness

This is perhaps the most widespread and frustrating symptom. Without enough iron, your body can’t make adequate haemoglobin — the protein in red blood cells responsible for carrying oxygen. That means your tissues and muscles aren’t getting the oxygen they need to produce energy.

Even after a full night’s sleep, you may feel:

• Drained
  

• Sluggish
  

• Like you’re “running on empty” all day

This kind of fatigue doesn’t improve with rest alone and may worsen with physical activity or exertion.

2. Brain fog and poor concentration

Low iron levels can affect brain function, especially attention span, memory, and mental clarity. This happens because the brain is highly sensitive to oxygen supply — and when haemoglobin is low, oxygen delivery to the brain drops.

You’re experiencing:

• Difficulty concentrating at work
  

• Forgetfulness
  

• Feeling mentally “foggy” or disconnected

3. Shortness of breath or dizziness

When your blood lacks sufficient haemoglobin, your heart and lungs have to work harder to compensate. You might find yourself:

• Getting winded easily while walking or climbing stairs
  

• Feeling lightheaded when standing up
  

• Experiencing mild chest tightness or palpitations

This is a sign your body is struggling to oxygenate tissues effectively — even with rest or minimal effort.

4. Unusual cravings (pica)

One lesser-known sign of iron deficiency is pica — the craving to eat non-food items such as:

• Ice
  

• Chalk
  

• Clay
  

• Paper or cardboard

Craving and chewing ice (known as pagophagia) is particularly common in people with low iron and may point to ongoing deficiency or poor absorption.

5. Pale skin, brittle nails, and hair thinning

Iron plays a key role in healthy circulation and cell growth, so your skin, hair, and nails are often early indicators of deficiency.

You may notice:

• Skin looking unusually pale or sallow
  

• Nails that chip, split, or form spoon-like indentations (koilonychia)
  

• Increased hair shedding or hair that feels thinner and more fragile

These symptoms often occur when iron stores (ferritin) are very low — even before haemoglobin drops significantly.

6. Persistently low blood test results

If you’ve been taking iron supplements and still see:

• Low ferritin (iron storage protein)
  

• Low haemoglobin
  

• Low serum iron or transferrin saturation

 …this is a red flag that your absorption is likely impaired, not just your intake.

Ferritin is especially important — it reflects your iron reserves. Even if your haemoglobin is normal, low ferritin can cause symptoms and indicate the body is struggling to store or absorb iron properly.

7. Cold hands and feet, or feeling cold all the time

Iron plays a role in regulating body temperature and supporting proper blood flow. If your iron levels are low, you may notice:

• Cold extremities
  

• Feeling chilled even in warm weather
  

• Needing extra layers when others feel fine

This is your body’s way of conserving oxygen-rich blood for essential organs.

8. Restless legs syndrome or unusual tingling sensations

Some people with iron deficiency report:

• An irresistible urge to move the legs (especially at night)
  

• Strange crawling, tingling, or “electric” sensations in the legs
  

• Disrupted sleep due to discomfort or leg movements

Iron is involved in dopamine production in the brain — a key factor in restless legs syndrome (RLS).

How to improve iron absorption naturally

If your body isn’t making the most of the iron supplements or iron-rich foods you’re giving it, there’s good news — you can support and improve iron absorption through a few key diet and lifestyle changes. In many cases, adjusting when and how you take your supplement, and what you pair it with, can make a big difference in your body’s ability to absorb iron.

1. Pair iron with vitamin C

Vitamin C (ascorbic acid) is one of the most powerful enhancers of non-heme iron absorption. It helps by converting iron into a more absorbable form and reducing the presence of inhibitors that may block its uptake in the gut.

How to apply this:

• Take your iron supplement with a glass of orange juice or water mixed with lemon.
  

• Include vitamin C-rich foods in iron-rich meals — e.g., tomatoes with spinach, or red capsicum with lentils.
  

• Great sources of vitamin C: citrus fruits, strawberries, kiwi, capsicum, broccoli, and papaya.

Even 50–100 mg of vitamin C alongside your supplement can significantly boost iron absorption.

 2. Avoid taking iron with iron blockers

Certain foods and drinks can bind to iron or alter gut conditions, making it harder for your body to absorb the mineral. Be mindful of your timing when taking supplements.

Avoid consuming the following within 1–2 hours of taking iron:

• Calcium-rich foods (dairy, fortified cereals, calcium supplements)
  

• Coffee and tea (contain polyphenols and tannins that inhibit absorption)
  

• Whole grains and legumes (contain phytates, which reduce bioavailability)
  

• Eggs (contain phosphoprotein which can inhibit iron uptake)
  

Tip: Take your supplement on an empty stomach for best results — unless it causes discomfort, in which case take it with a light meal free of iron-blocking foods.

3. Consider the timing and dosage

More isn’t always better. Studies show that taking lower doses of iron once daily or every other day may actually improve absorption compared to higher daily doses — especially for people with inflammation or gut issues.

That’s because:

• High doses may increase hepcidin, a hormone that limits iron uptake.
  

• Large amounts can irritate the stomach or cause side effects like constipation or nausea.

How to adjust:

• Try taking your supplement every second day if you’re experiencing side effects or poor results.
  

• Stick to one form of iron at a time unless advised otherwise by your healthcare provider.
  

• Track your results with regular blood tests to see if your levels improve.

4. Improve gut health

Since iron absorption happens primarily in the small intestine, a healthy gut lining is key. If your gut is inflamed or out of balance, your ability to absorb nutrients — not just iron — can be impaired.

Support your gut with:

• Prebiotics (e.g., garlic, onions, bananas, oats)
  

• Probiotics (e.g., yoghurt with live cultures, kefir, fermented vegetables)
  

• Anti-inflammatory foods like leafy greens, fatty fish, turmeric, and olive oil
  

• Adequate fibre to support a healthy microbiome
  

• Minimising processed sugar and alcohol, which can disrupt gut flora

If you suspect a deeper gut issue (like coeliac disease or IBD), it’s important to seek medical advice for appropriate testing and management.

5. Address underlying conditions or medication interference

If absorption isn’t improving with dietary tweaks and supplement adjustments, an underlying issue may be to blame. Certain medications and health conditions can reduce iron uptake or block its pathway.

Examples include:

• Proton pump inhibitors (PPIs) for reflux (e.g., omeprazole)
  

• Chronic inflammation or infection, which elevates hepcidin levels
  

• Autoimmune or gastrointestinal conditions (coeliac, Crohn’s, etc.)
  

• Heavy periods or bleeding, which may cause ongoing depletion
  

• Bariatric or bowel surgery altering the absorption sites

If you're dealing with one of these, working with your GP or a specialist is key. They may recommend different forms of supplementation (like intravenous iron) or address the root cause first.

6. Choose the right iron supplement

If your current iron supplement isn’t giving you results — or it's causing side effects like constipation or nausea — it might be worth re-evaluating the type of iron you’re taking. Not all iron supplements are created equal, and your body may tolerate or absorb some forms better than others.

Here are a few alternative options to consider:

Ferrous Bisglycinate

This is a chelated form of iron that tends to be more gentle on the stomach and better absorbed than traditional ferrous sulfate. It’s often recommended for those who experience digestive issues with standard iron tablets.

Liquid iron

Liquid formulations allow for easier dosing and are sometimes better tolerated, especially for those with sensitive digestion or those who struggle with swallowing tablets.

Liposomal iron

This is a newer form of iron supplement that uses liposome encapsulation to protect the iron as it passes through the digestive tract, improving absorption and reducing irritation. It’s suitable for those who haven’t responded well to conventional iron.

Liver supplements

Desiccated liver capsules (usually made from grass-fed beef liver) are a natural source of heme iron, the most easily absorbed form of iron. In addition to iron, they often provide vitamin A, B12, folate, and other cofactors that support red blood cell production and energy metabolism.

Liver supplements may be a good option for those looking for a wholefood-based iron boost, especially if they follow a low-meat diet but want the benefits of animal-based nutrients without consuming organ meats directly.

Shop Chief Beef Liver Supplements at Aussie Pharma Direct.

Note: While liver is nutrient-dense, it can be high in vitamin A, so it’s important to stick to recommended dosages and check with your healthcare provider — especially if you're pregnant or taking other vitamin A-rich supplements.

Plant-based or food-derived iron

For those on vegetarian or vegan diets, there are also iron supplements derived from spirulina, curry leaf, or beetroot. These are typically lower-dose, but they’re often combined with natural vitamin C sources to help improve absorption.

Ultimately, the right supplement for you depends on your individual needs, lifestyle, and how your body responds. If one type of iron isn’t working, trying a different formulation — or even incorporating liver-based or food-derived supplements.

Before you supplement more, check your iron stores

If you’ve been making changes to your diet and supplement routine but still feel constantly fatigued, short of breath, or dizzy, it may be time to check your iron stores more thoroughly. A simple blood test — specifically a ferritin test — can help determine whether your iron levels are low and how severe the deficiency might be.

Ferritin is a protein that stores iron in your body, and low ferritin levels are often the first sign of iron depletion, even before full-blown anaemia develops. Knowing your ferritin levels can also help your doctor tailor your iron supplementation and check if further investigation is needed (such as screening for gut issues, inflammation, or chronic blood loss)

If you're curious to get a quick check from home, there are now at-home ferritin test kits available — such as the TouchBio Ferritin / Iron Rapid Test — which can offer a convenient way to gain an initial insight into your iron status before following up with your healthcare provider. These tests can also be a useful tool for monitoring changes in your iron levels over time, especially if you’ve previously had low readings or are managing risk factors such as vitamin D deficiency, which may impact how your body absorbs and utilises iron. 

For anyone managing fluctuating iron levels, it’s helpful to have a couple of test kits on hand for peace of mind.

Shop TouchBio Ferritin / Iron Rapid Test at Aussie Pharma Direct.

Conclusion

From gut health and dietary pairings to underlying medical conditions, there are many factors that can affect your body’s ability to use the iron you give it.

This is why small changes can make a big difference. Whether it’s pairing your supplement with vitamin C, switching to a gentler iron formulation, or improving your digestive health, understanding how iron absorption works is the first step to getting better results.

That said, it’s always a good idea to speak with your doctor or a qualified health professional before making changes to your supplementation. If symptoms persist, or if your iron levels continue to drop despite best efforts, a deeper medical review may be needed to uncover the root cause.

Disclaimer: This blog is based on thorough research by our team, drawing on credible scientific and health sources to help you make informed decisions. However, it’s not a substitute for personalised medical advice. Always consult your healthcare provider for guidance tailored to your individual needs and health conditions.

Help Your Body Do More with the Iron You Give It

TouchBio Ferritin / Iron Rapid Test

The Touchbio Ferritin/Iron Rapid Test offers a convenient and cost-effective way to check for low iron levels from the comfort of your own home. Designed for ease of use, this kit includes everything you need to collect a small blood sample from your fingertip—no lab visits required. In just 5 minutes, you’ll receive clear, accurate results to help you detect potential iron deficiency early.

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Chief Organic Beef Liver Supplements

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Australian NaturalCare - Probiotic 32 Billion

When it comes to absorbing essential nutrients like iron, a healthy gut can make all the difference. Australian NaturalCare Probiotic 32 Billion is a high-strength, multi-strain probiotic designed to help restore and maintain a balanced intestinal flora—supporting not just digestion, but also your body’s ability to absorb key nutrients effectively. Best of all, it’s shelf-stable and doesn’t require refrigeration.

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Australian NaturalCare - Super C 1000

Vitamin C (ascorbic acid) is one of the most powerful enhancers of non-heme iron absorption—making it essential for those looking to optimise their iron intake. Australian NaturalCare Super C 1000 delivers a high-strength dose of vitamin C in a single, convenient tablet, helping you meet your daily requirements with ease.This powerful antioxidant formula is boosted with bioflavonoids, which work synergistically to improve vitamin C absorption and support its effective use in the body.

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AirPhysio Mucus Clearance & Lung Optimiser Devices

Iron deficiency can often lead to symptoms like tiredness and fatigue, which can affect your daily performance and overall vitality. While iron plays a role internally, your lung health is equally important in managing energy levels and improving overall wellbeing. AirPhysio is a drug-free, handheld device designed to naturally improve your lung capacity and mucus clearance.

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