05/03/2026
What does Functional Medicine say about low iron?
In the United States, low iron (iron deficiency) is primarily caused by unrecognized or chronic blood loss, followed by increased physiological needs and, less commonly in the U.S., poor dietary intake.
Iron deficiency affects roughly 14% of US adults, with prevalence rising significantly in specific demographics.
Here are the possible causes of low iron in the USA, ordered by highest frequency of occurrence based on current data:
Gastrointestinal (GI) Bleeding (Most Common in Men/Postmenopausal Women): Slow, chronic blood loss from the GI tract is the leading cause for adults. This is often due to:Peptic ulcers
Colorectal cancer or polyps
Inflammatory bowel disease (Crohn’s, ulcerative colitis)
Regular use of NSAIDs (e.g., aspirin, ibuprofen, naproxen), which cause stomach bleeding
Menstrual Blood Loss (Most Common in Women of Childbearing Age): Heavy or prolonged menstrual periods (menorrhagia) are the most common cause for premenopausal women.
Increased Physiological Needs (Pregnancy and Growth): Pregnant people have significantly higher iron needs to support increased blood volume and fetal development.
Infants and children (especially those consuming excessive cow’s milk) are also high-risk groups.
Malabsorption of Iron: Conditions that limit the body's ability to absorb iron, such as:Celiac disease
Bariatric surgery (weight loss surgery)
Atrophic gastritis (acid-suppressing medications)
Inadequate Dietary Intake (Less Common in USA): A diet low in bioavailable iron, such as strict, unplanned vegetarian or vegan diets.
Frequent Blood Donation: Donating blood too frequently without allowing time for iron stores to recover.
Note on Frequency: While anemia due to diet (DID) is cited in global studies, in the U.S. specifically, blood loss (menstrual or GI) is considered the most common reason for iron deficiency, followed by increased needs during pregnancy.
Risk Factors Affecting Frequency:
Age: Prevalence of iron deficiency increases in the elderly due to reduced absorption.
Race/Ethnicity: Studies have shown a higher prevalence of anemia in Black Americans compared to other groups in the US.
Income: Lower-income households in the US have a higher prevalence of anemia.
Iron dysregulation in the USA is highly prevalent, with a 2024 study estimating that nearly 1 in 3 Americans has some form of iron deficiency. The most common causes of iron dysregulation, ordered by frequency, are absolute iron deficiency, functional iron deficiency (iron sequestration), and hereditary hemochromatosis.
Most Common Causes of Iron Dysregulation (Highest Frequency)
Iron Deficiency Anemia (IDA) (Low Iron, Low Ferritin, High TIBC): The most common cause, caused by chronic blood loss (menstruation, GI bleeding) or low nutritional intake.
Anemia of Chronic Disease/Inflammation (Low/Normal Iron, High Ferritin, Low/Normal TIBC): Iron is present but "locked away" by inflammation.
Functional Iron Deficiency (Normal Iron, Normal/High Ferritin, Low/Normal TIBC): Common in obesity, diabetes, and CKD, where iron is present but cannot be used efficiently.
Hereditary Hemochromatosis (High Iron, High Ferritin, Low TIBC): A genetic disorder causing excessive absorption, affecting 1 in 300-500 people.
Liver Disease/Alcoholism (High Iron, High Ferritin, Low/Normal TIBC): Alcohol disrupts liver regulation, leading to liver iron overload.
Excessive Iron Supplementation (High Iron, High Ferritin, Low/Normal TIBC): Iatrogenic overload.Iron Panel Variations by Cause
Low Ferritin + High TIBC + Low Iron (Iron Deficiency): Indicates depleted stores (e.g., menorrhagia, malabsorption, iron-deficient diet).High Ferritin + Low/Normal TIBC + Low/Normal Iron (Anemia of Chronic Disease):
Chronic inflammation (e.g., infections, autoimmune diseases) or obesity causes the liver to produce more ferritin and less transferrin (lowering TIBC).
High Ferritin + High Iron + Low/Normal TIBC (Iron Overload): Typical of Hereditary Hemochromatosis or frequent blood transfusions.
Low TIBC + Low Iron + Normal/High Ferritin (Malnutrition/Liver Disease): Indicates poor nutritional status, such as protein deficiency or liver disease, which prevents the production of transferrin.
Key Findings on Prevalence
14% of US adults have absolute iron deficiency.
15% of US adults have functional iron deficiency.
6% of American young women have iron deficiency anemia.
16 million Americans have some form of iron overload (most commonly from metabolic syndrome, not genetic).40% of children under 5 are iron-deficient.
Once the cause of a patient's individual low iron &/or ferritin then you can strategically target the cause while supplementing iron, I like Floradix with herbs.
If iron deficiency is due to bleeding then stop or reduce bleeding is an important part of the treatment strategy.
Taking iron supplements when your levels are not low can lead to significant health concerns, primarily due to the production of free radicals through the Fenton reaction. When the body has excess iron that is not safely bound to proteins like transferrin, it becomes "free" and highly reactive.Free Radical Generation (Fenton Reaction)The primary concern is that excess iron acts as a pro-oxidant. It reacts with hydrogen peroxide in the body to produce hydroxyl radicals—the most destructive type of free radical.
These radicals cause oxidative stress, which damages:
Cellular Structures: Destroys cell membranes (lipid peroxidation), proteins, and DNA.
Organs: Leads to "ferroptosis" (iron-induced cell death), particularly in the liver, heart, and pancreas.
Intestinal Lining: Unabsorbed iron in the gut creates localized oxidative stress, causing inflammation, ulcers, and potentially increasing the risk of colorectal cancer.
Immediate and Long-Term RisksGastrointestinal Distress: Even in healthy individuals, high-dose iron can cause nausea, abdominal pain, constipation, and diarrhea.Organ Damage: Chronic excess can lead to liver cirrhosis, heart failure, and diabetes as iron deposits in vital tissues.Infection Risk: High levels of free iron can stimulate the growth of certain bacteria and viruses, making you more susceptible to infections.
Nutrient Interference: Excessive iron can block the absorption of other essential minerals, such as zinc, further weakening the body's antioxidant defenses.Summary of Iron Toxicity Stages. If an overdose occurs, symptoms typically progress through these stages:
Stage 1 (0–6 hrs): Severe vomiting, diarrhea, and stomach pain.
Stage 2 (6–48 hrs): A "latent" period where symptoms seem to improve, though internal damage continues.
Stage 3 (12–72 hrs): Critical condition involving shock, liver failure, and seizures.
Stage 4 (2–5 days): Potential death from liver necrosis or multi-organ failure. To avoid these risks, you should only take iron supplements if a healthcare provider has confirmed a deficiency through blood tests.