What Deficiency Causes Chronic Cough? The Surprising Nutritional Links

October 17, 2025 •

4 min read

While most chronic coughs are caused by conditions like asthma or GERD, research suggests a surprising link to nutritional health. A deficiency in certain vitamins and minerals can contribute to an unexplained chronic cough by affecting the nervous system and immune responses. This article explores the specific deficiencies that can be overlooked contributors to persistent coughing.

Quick Summary

Studies show that deficiencies in vitamin B12, iron, and vitamin D can be underlying factors for persistent coughing that doesn't respond to standard treatments. These nutrient shortages can increase airway inflammation, nerve sensitivity, and immune dysfunction, sustaining the cough reflex.

Key Points

Vitamin B12 Deficiency: Can cause sensory neuropathy, leading to a hypersensitive and irritable larynx that triggers a persistent, unexplained chronic cough.
Iron Deficiency: In women, iron deficiency has been linked to chronic cough by potentiating airway inflammation and weakening mucosal defenses.
Vitamin D Deficiency: Associated with persistent chronic cough, especially in severe cases, due to its role in regulating immune responses and inflammation in the respiratory tract.
Magnesium's Role: Plays a part in smooth muscle function and can increase airway hyperreactivity when deficient, which may exacerbate coughing, particularly in those with pre-existing lung conditions.
Complex Causality: Nutrient deficiencies are often a contributing factor alongside other issues, not always the sole cause, and require medical diagnosis and guidance for treatment.
Supplementation May Help: In cases where a deficiency is identified, proper supplementation under a doctor's care has shown to resolve or improve chronic cough symptoms.

The Surprising Link Between Nutrition and Persistent Coughing

For many, a chronic cough—one lasting eight weeks or more—can be a frustrating and debilitating condition with no clear cause. While common culprits like postnasal drip, asthma, and acid reflux are often investigated, medical research has uncovered a compelling connection between certain nutrient deficiencies and unexplained chronic cough. These nutritional gaps can influence the nervous system and immune function, creating an environment where the cough reflex is more easily triggered and sustained.

Vitamin B12 Deficiency and Sensory Neuropathy

One of the most significant links between a specific nutrient deficiency and unexplained chronic cough is with vitamin B12, also known as cobalamin. Deficiency can lead to sensory neuropathy, damaging peripheral nerves and potentially making throat and larynx nerves hypersensitive to irritants, thus triggering the cough reflex. Research indicates that patients with unexplained chronic cough and B12 deficiency may see improvement with supplementation. B12 deficiency can also cause other neurological symptoms like tingling, numbness, fatigue, and memory problems.

Iron Deficiency and Airway Inflammation

Iron is vital for immune function and regulating inflammation. Iron deficiency, especially in women, may impair immune function and weaken airway defense, increasing pro-inflammatory cytokines that sensitize the airway to irritants and prolong coughing. Studies on women with chronic cough have shown that iron deficiency can contribute to laryngeal and cough hyperresponsiveness, with supplementation improving symptoms. Common symptoms of iron deficiency include fatigue, paleness, and shortness of breath.

Vitamin D Deficiency and Respiratory Health

Vitamin D plays a key role in immune function and has anti-inflammatory properties. Low levels may weaken the immune response and contribute to respiratory tract inflammation. For those with chronic respiratory conditions, low vitamin D is linked to worse symptoms and persistent cough. Research, such as the Rotterdam Study, has associated severe vitamin D deficiency with persistent chronic cough in adults, and generally, low vitamin D is linked to increased risk of respiratory infections that can prolong a cough.

Other Potential Contributors: Magnesium and Calcium

Magnesium and calcium also influence respiratory function, although their link to chronic cough is less direct.

Magnesium: As a muscle relaxant, magnesium supports smooth muscle function in airways. Deficiency can increase airway hyperreactivity and inflammation, potentially contributing to bronchoconstriction.
Calcium: An imbalance with low magnesium can make bronchial smooth muscles contract more easily. Extremely low calcium (hypocalcemia) can cause muscle spasms, including in the throat, which might worsen coughing.

Comparison Table: Nutritional Deficiencies and Chronic Cough


Deficiency	Mechanism Leading to Cough	Associated Symptoms	Food Sources
Vitamin B12	Causes sensory neuropathy, leading to an irritable larynx and hypersensitive cough reflex.	Numbness, tingling, fatigue, memory problems, paleness.	Meat, fish, poultry, eggs, dairy products, fortified cereals.
Iron	Impairs immune function, increases airway inflammation, and weakens mucosal defense.	Fatigue, paleness, shortness of breath, headache.	Red meat, poultry, fish, lentils, beans, spinach, fortified cereals.
Vitamin D	Contributes to immune dysfunction and chronic inflammation, exacerbating respiratory symptoms.	Low energy, frequent infections, depression, bone pain.	Sun exposure, fatty fish, fortified milk and cereals, supplements.
Magnesium	Can increase airway hyperreactivity and muscle contraction, linked to respiratory muscle dysfunction.	Muscle cramps, spasms, fatigue, irregular heartbeat.	Nuts, seeds, leafy greens, whole grains, avocados.

What to Do If You Have a Persistent Cough

If you have a chronic cough that has not responded to traditional treatments, considering a nutritional link may be beneficial, but this must be done in consultation with a healthcare professional.

Consult a Doctor: Always begin by seeking professional medical advice. A doctor can rule out more serious causes and perform blood tests to check for specific nutrient deficiencies.
Get Tested: Based on your symptoms, your doctor can order tests for B12, iron, and vitamin D levels. Addressing these deficiencies through diet or supplementation under medical supervision can be an effective part of a treatment plan.
Optimize Your Diet: Eating a balanced, nutrient-dense diet rich in fruits, vegetables, lean protein, and whole grains is foundational to overall health. Focus on incorporating the food sources mentioned above. You can read more about dietary strategies for managing cough symptoms here: [https://route2health.com/blogs/news/the-role-of-diet-in-managing-cough-foods-to-eat-and-avoid].

Conclusion

While nutritional deficiencies might not be the most common cause of a chronic cough, emerging research highlights their potential as overlooked contributing factors, especially in unexplained cases. Vitamin B12 deficiency can heighten nerve sensitivity, iron deficiency can increase airway inflammation, and low vitamin D can weaken immune responses, all of which can sustain a persistent cough. For those struggling with a long-lasting cough that conventional treatments fail to address, investigating underlying nutritional status may offer a path to resolution. Always work with your healthcare provider to get a proper diagnosis and treatment plan that addresses all potential causes. Early detection and treatment of these deficiencies are simple steps that can lead to significant improvements in respiratory health.

Frequently Asked Questions

Yes, a deficiency in vitamin B12 can cause sensory neuropathy that leads to an irritable and hypersensitive larynx, which can contribute to an unexplained chronic cough.

Yes, particularly in women, iron deficiency has been linked to chronic idiopathic cough by affecting the immune system and increasing airway inflammation. Supplementation has been shown to improve cough symptoms in some cases.

Vitamin D deficiency has been associated with persistent chronic cough, as it can impair immune function and promote chronic respiratory inflammation. Studies show that severe deficiency is more prevalent in those with chronic cough.

While not a direct cause, magnesium deficiency can increase airway hyperreactivity and affect respiratory muscle function, potentially contributing to coughing in individuals with conditions like asthma or COPD.

The only way to determine if a deficiency is related to your cough is to consult a doctor. A healthcare provider can order blood tests for specific nutrient levels and rule out other, more common causes of chronic cough.

If a nutrient deficiency is the underlying cause, addressing it with supplementation can resolve the cough. However, supplementation should only be done under a doctor's supervision, as deficiencies are often contributing factors rather than the sole cause.

Unexplained chronic cough refers to a persistent cough lasting more than eight weeks for which standard diagnostic tests fail to find a clear cause. In these cases, nutritional factors like vitamin deficiencies may be considered.