Why am I deficient in vitamin B6? Understanding the root causes

October 25, 2025 •

3 min read

While severe dietary vitamin B6 deficiency is relatively rare in developed countries, marginal deficiency is more common due to various underlying issues, according to the National Institutes of Health. Understanding these factors is the first step to answering the question: Why am I deficient in vitamin B6?

Quick Summary

Vitamin B6 deficiency often stems from poor absorption caused by chronic illness, certain medications, or excessive alcohol use. It can also arise from increased metabolic demand and is frequently linked to other B vitamin deficiencies, impacting neurological, dermatological, and immune function.

Key Points

Beyond Diet: Deficiency is often caused by underlying medical conditions, alcohol use, or specific medications, not just inadequate intake.
Malabsorption Matters: Chronic gastrointestinal and autoimmune disorders like Celiac or Crohn's can severely impair vitamin B6 absorption.
Medication Interference: Some drugs, particularly isoniazid and certain anticonvulsants, can actively deplete the body's vitamin B6 stores.
Kidney and Liver Health: Impaired kidney and liver function significantly increase the risk of developing a B6 deficiency.
Look for Symptoms: Signs like peripheral neuropathy, dermatitis, and anemia can point toward a B6 deficiency, though symptoms can be vague and overlap with other conditions.
Treatment is Targeted: Effective treatment involves addressing the root cause, dietary changes, and often, supplementation under medical supervision.

Understanding the Role of Vitamin B6

Vitamin B6, or pyridoxine, is a water-soluble vitamin essential for over 100 enzymatic reactions in the body. It plays a critical role in amino acid metabolism, red blood cell formation, brain development, and immune function. Since the body doesn't store much B6, a steady intake is necessary. A deficiency can occur when this intake is insufficient or other factors interfere with its use.

Primary Causes of Vitamin B6 Deficiency

Diet is typically a sufficient source of vitamin B6 for healthy people. However, certain dietary choices and food processing methods can impact B6 levels.

Inadequate Diet: Severe malnutrition or diets lacking in B6-rich foods, particularly in areas with limited food access, are direct contributors.
Restricted Diets: Vegetarians and vegans might have a higher risk because B6 from animal sources is more easily absorbed than from plants. Fortified foods and legumes can help.

Secondary Causes: Chronic Conditions and Malabsorption

Beyond diet, medical conditions that impact the body's ability to absorb or process vitamin B6 are common causes of deficiency.

Alcohol Dependence

Excessive alcohol intake significantly increases the risk of vitamin B6 deficiency. Alcohol hinders the absorption of the vitamin and speeds up its removal from the body. It can also damage the liver, which is crucial for activating B6. Thus, chronic alcohol use disorder is closely linked to low B6 levels.

Gastrointestinal Disorders

Conditions that impair nutrient absorption in the small intestine can lead to B6 deficiency.

Celiac disease: Damages the intestinal lining, reducing absorption.
Inflammatory Bowel Diseases: Conditions like Crohn's and ulcerative colitis cause inflammation that interferes with nutrient uptake.
Bariatric Surgery: Can alter the digestive tract and decrease nutrient absorption.

Kidney Disease

Individuals with poor kidney function, especially those on dialysis, are more susceptible to B6 deficiency. This is because kidney problems can lead to increased loss of the active form of B6.

Autoimmune Disorders

Chronic inflammation associated with conditions like rheumatoid arthritis can accelerate the breakdown of vitamin B6, requiring a higher intake.

The Impact of Medications

Certain medications can interfere with how the body uses vitamin B6, potentially leading to deficiency with long-term use. Supplementation may be necessary for patients taking these drugs.

Isoniazid: An antibiotic that inactivates vitamin B6.
Anticonvulsants: Some seizure medications can increase B6 breakdown.
Hydralazine: A blood pressure medication.
Penicillamine: Used for certain diseases like Wilson's disease.
Theophylline: A drug for respiratory issues that can lower B6 levels.

Comparing Causes of Vitamin B6 Deficiency


Cause	Mechanism	At-Risk Populations	Common Associated Conditions
Poor Dietary Intake	Lack of B6-rich foods (meat, fish, vegetables, legumes).	Strict vegans, vegetarians, elderly, individuals with malnutrition.	General malnutrition, other B vitamin deficiencies.
Malabsorption Disorders	Impaired intestinal absorption of nutrients.	Celiac disease, Crohn's disease, Ulcerative Colitis, post-bariatric surgery patients.	Inflammatory Bowel Disease (IBD), autoimmune diseases.
Chronic Alcohol Abuse	Decreased absorption, increased excretion, and impaired liver metabolism.	Individuals with alcohol dependence.	Liver disease, thiamine deficiency (Wernicke's encephalopathy).
Kidney Disease	Excessive clearance of vitamin B6.	Patients with chronic renal insufficiency, on hemodialysis.	Renal failure, other vitamin and mineral imbalances.
Medications	Interference with B6 metabolism or activation.	Patients on isoniazid, some anticonvulsants, hydralazine, penicillamine.	Tuberculosis, epilepsy, rheumatoid arthritis, Wilson's disease.

Symptoms of Vitamin B6 Deficiency

Symptoms of B6 deficiency vary; mild cases may show no signs. More significant deficiencies can affect several body systems:

Neurological: Includes peripheral neuropathy, depression, confusion, and sometimes seizures.
Dermatological: May involve seborrheic dermatitis, cheilosis, and glossitis.
Hematological: Can cause microcytic anemia.
Immune System: May lead to a weakened immune response.

Diagnosing and Treating a Deficiency

Diagnosis involves a medical history, including diet and medications, and often blood tests to measure active B6 levels (plasma PLP). Treatment typically focuses on the underlying cause, dietary changes, and often, B6 supplementation, with dosage adjusted to the deficiency's severity. IV administration may be used if oral intake isn't possible. Increasing intake of B6-rich foods like chickpeas, beef liver, tuna, salmon, potatoes, and bananas is also key.

Conclusion: Taking Control of Your Vitamin B6 Levels

Answering why am I deficient in vitamin B6? often requires looking beyond diet to include chronic illnesses, medications, and lifestyle. Identifying and treating the root cause with healthcare guidance is crucial for effective management. Being aware of symptoms and discussing concerns with a doctor is vital for restoring health.

For more detailed information on vitamin B6, you can consult the National Institutes of Health fact sheet.

Frequently Asked Questions

Early or mild deficiency may have minimal or no symptoms. As it progresses, initial signs can include fatigue, irritability, a red and sore tongue (glossitis), and scaling on the lips (cheilosis).

Yes, several medications can cause a functional vitamin B6 deficiency. These include isoniazid (for tuberculosis), some anticonvulsants (like phenytoin and carbamazepine), hydralazine, and penicillamine.

Yes, chronic alcohol use is a major risk factor. It impairs the absorption of vitamin B6 and increases its metabolic clearance, leading to lower levels.

Conditions that cause malabsorption and can lead to vitamin B6 deficiency include celiac disease, inflammatory bowel diseases like Crohn's and ulcerative colitis, and bariatric surgery.

Yes, impaired kidney function, especially in patients on dialysis, is linked to an increased risk of vitamin B6 deficiency. This is due to increased metabolic clearance of the active form of the vitamin.

Diagnosis is based on a clinical evaluation of symptoms and risk factors, often confirmed with blood tests that measure the level of pyridoxal 5-phosphate (PLP), the active form of B6.

Good dietary sources of vitamin B6 include chickpeas, beef liver, tuna, salmon, potatoes, fortified breakfast cereals, and bananas.