What Causes Low Ferritin Levels in Functional Medicine?

December 14, 2025 •

4 min read

According to one study, low ferritin with normal hemoglobin is a common, yet often overlooked, hematological disorder. Functional medicine goes beyond simply replacing iron to uncover the specific root causes contributing to low ferritin levels, which can manifest as fatigue, hair loss, and other symptoms.

Quick Summary

Functional medicine identifies the underlying reasons for low ferritin, such as poor gut absorption, chronic inflammation, dietary issues, and blood loss, offering a comprehensive approach to addressing iron deficiency and its related symptoms.

Key Points

Beyond Diet: Low ferritin in functional medicine is often linked to poor absorption or chronic inflammation, not just inadequate iron intake.
Gut-Iron Axis: Poor gut health from issues like SIBO, leaky gut, or low stomach acid is a primary cause of impaired iron absorption.
Inflammation's Role: Chronic inflammation increases hepcidin, a hormone that traps iron in storage, creating a 'functional iron deficiency'.
Optimal Lab Ranges: Functional medicine uses optimal rather than conventional reference ranges to diagnose iron deficiency earlier, often at a ferritin level below 70-100 ng/mL.
Underlying Conditions: Low ferritin can signal underlying issues such as celiac disease, H. pylori infection, or chronic blood loss from heavy periods.
Holistic Solutions: Treatment involves addressing the root cause—healing the gut, reducing inflammation, and optimizing diet, not just supplementing iron.

Understanding Ferritin from a Functional Medicine Perspective

Unlike conventional medicine, which often focuses on treating symptoms, functional medicine aims to identify and address the root causes of health issues. When it comes to low ferritin levels, this means looking beyond simple iron intake to consider factors like digestion, inflammation, and cellular function. Ferritin is a protein that stores iron, and low levels indicate depleted iron reserves in the body. However, a functional medicine approach recognizes that low ferritin isn't just about a lack of dietary iron; it’s a symptom of a deeper imbalance.

The Critical Role of Gut Health in Ferritin Levels

Your digestive system is the primary site for iron absorption, making gut health a central pillar of functional medicine's approach to low ferritin. Conditions that damage the intestinal lining or disrupt the gut microbiome can significantly impair the body's ability to absorb iron, even from an iron-rich diet. This poor absorption, or malabsorption, is a key reason many people struggle with low ferritin despite taking iron supplements.

Leaky Gut Syndrome: Increased intestinal permeability, or "leaky gut," allows toxins and undigested food particles to enter the bloodstream, triggering systemic inflammation and compromising nutrient absorption.
Small Intestinal Bacterial Overgrowth (SIBO): An overgrowth of bacteria in the small intestine can lead to poor nutrient absorption and inflammation, both of which contribute to low iron stores.
Low Stomach Acid: Gastric acid is necessary to convert iron into a form that can be absorbed by the body. Medications that reduce stomach acid, or simply age-related decline, can hinder this process.
Inflammatory Bowel Disease (IBD) and Celiac Disease: These autoimmune and inflammatory conditions directly damage the intestinal lining, severely affecting iron absorption.

The Impact of Chronic Inflammation and Infection

Chronic inflammation is a significant driver of low ferritin levels in functional medicine. The body responds to inflammation by producing hepcidin, a hormone that regulates iron metabolism. High levels of hepcidin can trap iron within storage cells and reduce its absorption from the diet, creating a state of "functional iron deficiency". In this state, iron stores may appear normal or even high in lab tests, but the body cannot properly utilize the iron that is available.

Examples of inflammatory conditions that can cause this issue include:

Autoimmune diseases like rheumatoid arthritis.
Chronic infections, such as H. pylori.
Obesity, which is associated with systemic inflammation.

Dietary and Lifestyle Factors

While inadequate dietary intake is a classic cause of low iron, functional medicine emphasizes that the type of iron consumed and other dietary factors are equally important.

Plant-Based Diets: Non-heme iron from plant sources is less bioavailable than heme iron from animal products. Without careful planning, individuals on vegetarian or vegan diets may have inadequate iron intake.
Food Sensitivities: Undiagnosed sensitivities, like non-celiac gluten sensitivity, can cause low-grade gut inflammation that impairs iron absorption over time.
Nutrient Antagonists: Consuming certain foods and beverages with iron-rich meals can inhibit absorption. For example, excessive intake of tea, coffee, and dairy products containing calcium can interfere with iron uptake.
Heavy Menstrual Bleeding: Excessive blood loss during menstruation is a very common cause of low ferritin in premenopausal women and is often overlooked or normalized.

Comparison of Conventional vs. Functional Medicine Approach


Feature	Conventional Medicine Approach	Functional Medicine Approach
Focus	Treat the symptom (low ferritin)	Identify and address the root cause
Diagnosis	Relies on standard lab ranges; may overlook non-anemic iron deficiency.	Uses optimal lab ranges; considers inflammation and gut function.
Lab Testing	Measures serum iron, ferritin, and CBC.	Includes advanced testing for gut health, inflammation markers, and nutrient deficiencies.
Treatment	Iron supplements, sometimes without addressing absorption issues.	Diet modification, gut repair protocols, reducing inflammation, addressing infections, and targeted supplementation.
Patient Involvement	Patient follows prescribed protocol.	Patient is an active participant in their healing journey.
Underlying Issues	May be missed if labs fall within the 'normal' range.	Investigated thoroughly as the source of imbalance.

Conclusion: A Holistic Approach to Low Ferritin

Functional medicine provides a comprehensive framework for understanding and resolving low ferritin levels by addressing the multiple interconnected systems of the body. Instead of merely supplementing iron, this approach investigates the critical roles of gut health, chronic inflammation, diet, and lifestyle. By identifying and treating the root causes, patients can achieve long-term, sustainable improvements in their iron status, energy, and overall well-being. This shift in perspective moves beyond symptom management to truly restore the body's balance. For more in-depth information, consider exploring research from the National Institutes of Health.

Potential Complications of Untreated Low Ferritin

Chronic, untreated low ferritin can lead to a range of health complications beyond simple fatigue. The body requires iron for numerous functions, including energy production in the mitochondria and hormone regulation. When iron stores are consistently low, these systems can falter, leading to more severe issues.

Worsened Thyroid Function: Low iron can negatively impact thyroid function, contributing to symptoms of hypothyroidism like weight gain and fatigue.
Hair Loss: Iron deficiency is a well-documented cause of hair loss.
Mood and Cognitive Issues: Low iron can affect mood regulation, concentration, and cognitive function.
Restless Leg Syndrome: There is a known link between low ferritin and restless leg syndrome.

By taking a functional approach and addressing the root cause, it is possible to prevent these complications and support overall health more effectively.

Frequently Asked Questions

Iron deficiency means your body doesn't have enough iron. Low ferritin is an indicator of this condition, as ferritin is the protein that stores iron. Low ferritin levels often appear before full-blown iron-deficiency anemia, meaning your storage reserves are running low.

Yes, absolutely. Since iron is absorbed in the small intestine, conditions that damage the gut lining (like Celiac disease or leaky gut) or affect the gut microbiome (like SIBO) can severely impair your ability to absorb iron from food or supplements, leading to low ferritin.

Chronic inflammation causes the body to release hepcidin, a hormone that blocks iron transport and absorption. This traps iron in storage and reduces its availability for vital functions, creating a 'functional iron deficiency' even if your total body iron stores aren't fully depleted.

While conventional labs might accept much lower values, many functional medicine practitioners consider optimal ferritin levels to be between 70-100 ng/mL for robust energy and cellular function, especially for women.

Yes, proper stomach acid is needed to convert iron into a form that can be absorbed. If you have low stomach acid, whether due to age, diet, or medication use (like proton pump inhibitors), your iron absorption can be compromised.

If your diet is rich in iron but your ferritin remains low, the issue is likely absorption, not intake. Functional medicine would investigate underlying problems like gut dysfunction, food sensitivities, or chronic inflammation that prevent your body from properly utilizing the iron you consume.

The first step is a thorough investigation to identify the root cause. This often involves more detailed blood work, assessing gut health, and examining dietary and lifestyle factors, rather than just starting a high-dose iron supplement.