What Causes Iron Deficiency: The Underlying Factors You Need To Know
- Renee Grandi
- May 27
- 5 min read
Iron deficiency is one of the most common nutrient deficiencies globally, yet it's often treated in isolation without fully investigating the underlying cause. In integrative and functional medicine, iron deficiency is not viewed as a standalone issue but as a downstream effect of imbalances in digestion, hormones, immunity, inflammation, or metabolism. To truly resolve iron deficiency, we must explore the why beneath the lab results.
This article provides a comprehensive breakdown of how iron is absorbed, utilised, and lost in the body, what symptoms it creates, what interferes with it, and how we can rebuild it from the inside out.
Signs and Symptoms of Iron Deficiency
Iron deficiency affects multiple systems in the body. It can show up subtly at first and become progressively more debilitating.
Common symptoms include:
Fatigue and low stamina
Brain fog and poor concentration
Anxiety and increased nervousness
Heart palpitations or fluttering
Feeling light-headed, especially on standing
Cold hands and feet
Pale or sallow skin
Period pain and/or heavy periods
Hair loss or brittle hair
Brittle nails with ridging
Headaches, especially premenstrually
Restless legs at night
Poor sleep or insomnia
Increased PMS and mood swings
Low immune resilience / frequent illness
Poor wound healing
Biochemistry of Iron: Storage, Absorption, and Utilisation
Iron plays a vital role in the transport of oxygen (via haemoglobin), mitochondrial energy production, neurotransmitter synthesis (especially dopamine and serotonin), DNA replication, and immune cell function.
Storage: Iron is stored primarily in the liver, spleen, and bone marrow. It is stored as ferritin, a protein that buffers the body against both iron overload and deficiency.
Absorption: Iron absorption occurs in the duodenum and proximal jejunum (upper small intestine). It depends on:
Adequate stomach acid (HCl) to release iron from food
A healthy gut lining (no inflammation or damage)
The presence of vitamin C, which enhances non-heme iron absorption
Transport & Utilisation:
Iron binds to transferrin in the blood and is transported to cells, especially the bone marrow for red blood cell production.
Cells use iron in mitochondria, enzymes, and for oxygen transport.
It is tightly regulated because excess free iron can drive oxidative stress.
Root Causes of Iron Deficiency in Integrative Medicine
1. Low Stomach Acid (Hypochlorhydria)
Adequate hydrochloric acid is essential to release iron from dietary sources, particularly heme iron from red meat. Stress, ageing, H. pylori infections, and antacids/PPIs can all lower stomach acid and reduce iron uptake.
2. Heavy Menstrual Bleeding (Menorrhagia)
Blood loss is the most apparent cause of iron depletion. Common causes of heavy periods include:
Endometriosis
Adenomyosis
PCOS with oestrogen dominance
Uterine fibroids
Perimenopausal anovulatory cycles
Signs of heavy bleeding include:
Soaking pads/tampons every 1–2 hours
Needing to double up on protection
Bleeding longer than 6 days
Passing clots larger than a 10-cent coin
Bleeding more than 80mls of blood per period (5 tbsps)
3. Inflammatory Gut Conditions
Diseases like:
Coeliac disease
Crohn’s disease
Ulcerative colitis
Irritable bowel syndrome with inflammation
Inflammation damages the intestinal villi where iron is absorbed and may raise hepcidin, a hormone that blocks iron absorption during inflammation.
4. Coeliac Disease and Non-Coeliac Gluten Sensitivity
Even without overt symptoms, gluten can cause low-grade villous atrophy, reducing surface area for iron absorption. Coeliac disease is often undiagnosed in cases of unexplained iron deficiency.
5. Underlying Chronic Viral Infections
Chronic or reactivated viral infections can severely impact mitochondrial function, immune signalling, and nutrient utilisation.
Key viruses include:
Epstein-Barr Virus (EBV)
Cytomegalovirus (CMV)
Herpes Simplex Virus (HSV-1/2)
Human Herpesvirus 6 (HHV-6)
These viruses increase cytokine activity, suppress the gut, increase inflammation, and trigger elevated hepcidin levels (which block iron from entering circulation). Symptoms may include chronic fatigue, joint pain, swollen glands, poor immune recovery, and flares during stress.
6. Food Intolerances / Allergies
Common triggers like gluten, dairy, eggs, or food chemicals (histamine, salicylates) can create mucosal inflammation, impairing absorption over time.
7. Dysbiosis & Parasitic Infections
Pathogenic bacteria and parasites compete for iron and damage the gut lining. Blastocystis hominis and Dientamoeba fragilis are common culprits in unexplained iron deficiency with fatigue and IBS-like symptoms.
8. Postpartum Iron Depletion
Pregnancy increases demand dramatically, and many women begin the postpartum period in a state of significant deficiency due to blood loss and increased needs during recovery.
Optimal Pathology Testing for Iron Status
Test | Normal Range | Optimal Range | Notes |
Ferritin | 30–300 µg/L | 60–100 µg/L | Below 30 indicates storage deficiency. Over 150 may indicate inflammation. |
Serum Iron | 10–30 µmol/L | 18–25 µmol/L | Can fluctuate daily. Best taken fasted. |
Transferrin Saturation | 20–45% | 30–40% | Indicates how much iron is bound and available for use. |
TIBC (Total Iron Binding Capacity) | 45–72 µmol/L | 50–65 µmol/L | High levels may reflect deficiency. |
CRP / hs-CRP | <5 mg/L | <1 mg/L | Elevated in inflammation, which skews ferritin. |
Vitamin B12 | 140–700 pmol/L | 400–700 pmol/L | Often low alongside iron. |
Folate | >10 nmol/L | >15 nmol/L | Required for red blood cell formation. |
TSH / Free T3 / Free T4 | Lab-dependent | Optimal thyroid function needed for iron use. |
Iron Supplementation: Best Practices
Use highly absorbable forms: Iron bisglycinate or liposomal iron.
Take with vitamin C: 500 mg improves absorption 2–3x.
Avoid co-ingestion with: Calcium, zinc, magnesium, dairy, coffee/tea, high-fibre meals.
Timing: Take away from meals on an empty stomach, where tolerated.
Reassess ferritin every 8–12 weeks, not sooner, to allow time for levels to shift.
Iron-Rich & Blood-Building Foods
Animal Sources (heme iron):
Liver (chicken/beef)
Red meat (beef, lamb, kangaroo)
Oysters, sardines, shellfish
Plant-Based (non-heme):
Lentils, chickpeas, kidney beans
Pumpkin seeds, sesame seeds
Dark leafy greens (cooked)
Blackstrap molasses
Beetroot
Parsley
Blood-building foods:
Bone broth
Nettle tea
Dates and prunes
Egg yolks
Red root vegetables
Best prepared as:
Slow-cooked, warming meals that support spleen/stomach qi (TCM perspective)
With warming spices: ginger, turmeric, cinnamon, fennel
What Interferes With Iron Absorption & Utilisation?
Caffeine (within 1 hour of supplementation)
Calcium or dairy-rich meals
Excessive fibre or phytates (in grains)
Inflammation / chronic infections
Low stomach acid
Stress and cortisol dysregulation
When Iron Is Low, Look Beyond the Labs
Low iron rarely exists in isolation. It's often part of a broader functional picture involving:
Hypothyroidism (T4 to T3 conversion requires iron)
Adrenal dysfunction (high cortisol depletes iron stores)
Mood disorders (low dopamine, serotonin linked to iron and B6 status)
Histamine intolerance (iron is a cofactor in DAO enzyme)
Period pain (linked to prostaglandin and magnesium imbalances, worsened by low iron)
Final Thoughts & Practitioner Support
If you're dealing with chronic fatigue, anxiety, dizziness, or hormone symptoms that haven’t improved with iron alone, it’s likely there’s more going on beneath the surface. Correcting iron deficiency requires more than just topping up a number. It means understanding the full picture of gut health, hormones, immune function, inflammation, and nutrient synergy.
If you’d like support navigating this process and rebuilding your health in a tailored, efficient way, I offer one-on-one consultations through my clinic.
You can book a session or a free 10-minute clarity call here: www.womensintegrativehealthclinic.com.au/services-page
Comments