What Causes Your B6 to be Low? A Comprehensive Guide to Pyridoxine Deficiency

November 19, 2025 •

3 min read

According to estimates from the Centers for Disease Control (CDC), a portion of the population may experience a marginal vitamin B6 deficiency. While a lack of B6 can result from diet, many other factors can cause your B6 to be low and lead to a range of health complications. This guide explores the diverse reasons behind low vitamin B6 and how to identify potential causes.

Quick Summary

Low vitamin B6 can result from poor dietary intake, certain medications, malabsorption issues, chronic diseases like kidney or autoimmune disorders, or excessive alcohol use. Identifying the root cause is key to effective management.

Key Points

Alcohol Abuse: Chronic alcohol consumption interferes with B6 absorption and increases its excretion, making it a primary risk factor for deficiency.
Medication Interference: Certain drugs, like the antibiotic isoniazid and some anticonvulsants, directly interfere with B6 metabolism, leading to reduced levels.
Chronic Illnesses: Conditions affecting the kidneys, liver, and immune system (e.g., celiac disease, chronic kidney disease) can cause low B6 by impairing absorption or increasing metabolic demand.
Dietary Factors: While less common, insufficient intake from a poor or restrictive diet, particularly for vegans and vegetarians, can cause low B6 levels.
High Demand States: Periods of increased physiological need, such as pregnancy and breastfeeding, can make an individual more susceptible to deficiency.

Vitamin B6, also known as pyridoxine, is a water-soluble vitamin essential for over 100 enzyme reactions in the body. It plays a crucial role in metabolism, brain development, and immune function. Since the body does not store large amounts of B6, a steady daily intake is required. When this intake is inadequate or its metabolism is impaired, a deficiency can develop. While often mild, prolonged low levels of B6 can lead to symptoms such as fatigue, skin inflammation, confusion, and peripheral neuropathy. Understanding the potential causes is the first step toward prevention and treatment.

Medical and Lifestyle Causes of Low B6

Alcoholism and Excessive Alcohol Use

Chronic heavy alcohol consumption is a well-documented risk factor for vitamin B6 deficiency. Alcohol interferes with the absorption of B6 in the intestines and also increases the rate at which the vitamin is broken down and excreted from the body. This dual-impact significantly depletes B6 stores, and many individuals with alcohol dependence also have poor overall nutrition, further exacerbating the issue.

Malabsorption Syndromes and GI Disorders

Conditions that affect the gastrointestinal tract and hinder nutrient absorption can easily lead to low B6 levels. These include:

Celiac Disease: An autoimmune disorder where the immune system reacts to gluten, damaging the lining of the small intestine and impairing nutrient absorption.
Crohn's Disease and Ulcerative Colitis (Inflammatory Bowel Disease): Chronic inflammatory conditions that can decrease the gut's ability to absorb vitamins effectively.
Bariatric Surgery: Procedures that alter the digestive system can reduce the surface area for absorption, increasing the risk of deficiency.

Chronic Kidney Disease

Individuals with impaired renal function, especially those undergoing hemodialysis, are at a higher risk of B6 deficiency. The dialysis process can remove B6 from the bloodstream, and kidney disease can also affect the body's ability to retain the vitamin. Close monitoring and supplementation are often necessary for these patients.

Autoimmune Disorders

Certain autoimmune disorders, like rheumatoid arthritis, can increase the breakdown (catabolism) of B6 in the body. This increased metabolic demand can lead to a deficiency, even with a seemingly adequate dietary intake.

Medication-Induced Depletion

Several medications are known to interfere with B6 metabolism or deplete body stores. It is crucial for individuals on these long-term therapies to discuss B6 supplementation with their doctor. Medications include:

Isoniazid: An antibiotic for tuberculosis that inhibits a B6 synthesis enzyme.
Penicillamine: Used for conditions like rheumatoid arthritis and Wilson disease.
Hydralazine: A medication for high blood pressure.
Anticonvulsants: Some epilepsy drugs can interfere with B6 metabolism.
Corticosteroids: These can deplete B6 with long-term use.

Comparative Causes of Low B6 Levels


Cause	Mechanism of B6 Reduction	Examples
Inadequate Diet	Insufficient intake of B6-rich foods, processing of grains removing vitamins.	Restrictive diets (vegan/vegetarian), reliance on processed foods.
Malabsorption	Conditions damaging the GI tract or reducing absorption surface area.	Celiac disease, Crohn's disease, bariatric surgery.
Alcohol Abuse	Impairs absorption, increases excretion, and leads to poor nutrition.	Chronic alcoholism.
Kidney Dysfunction	Increased clearance of B6 during dialysis or general kidney impairment.	End-stage renal disease, hemodialysis.
Medication Use	Chemical interference with B6 metabolism or depletion of body stores.	Isoniazid, penicillamine, anticonvulsants.
High Metabolic Demand	Increased physiological requirement for B6.	Pregnancy, lactation.

Conclusion

While a direct dietary deficiency of vitamin B6 is relatively uncommon in developed countries due to fortified foods, low B6 levels are often a secondary issue stemming from more complex medical or lifestyle factors. Chronic conditions such as kidney or autoimmune diseases, malabsorption disorders, alcoholism, and the long-term use of certain medications are all significant contributors. Recognizing these root causes is vital for effective management, which often involves not only dietary changes but also targeted supplementation or addressing the underlying condition with a healthcare provider. If you suspect you have a B6 deficiency, a medical evaluation can help determine the cause and the best course of action.

For more information on the functions and dietary sources of vitamin B6, consult the fact sheet from the NIH Office of Dietary Supplements: Vitamin B6 - Health Professional Fact Sheet.

Frequently Asked Questions

Symptoms can include fatigue, skin inflammation (dermatitis), a sore and red tongue (glossitis), cracked lips (cheilosis), depression, confusion, and nerve damage resulting in numbness or tingling (peripheral neuropathy).

Excellent food sources include fish (tuna, salmon), poultry, chickpeas, potatoes, organ meats (beef liver), bananas, avocados, and fortified cereals.

Yes, excessive alcohol consumption is a major cause of vitamin B6 deficiency. It impairs the vitamin's absorption in the gut and speeds up its breakdown and excretion by the body.

Chronic health conditions such as kidney disease (especially for those on dialysis), malabsorption disorders (like celiac or Crohn's), and autoimmune diseases (such as rheumatoid arthritis) can all cause low B6 levels.

Yes, older adults may be at a higher risk due to several factors, including a lower dietary intake and potential underlying conditions that can affect absorption and metabolism.

A doctor can diagnose a deficiency based on a physical examination, a review of your symptoms and medical history, and blood tests to measure the active form of B6, pyridoxal 5'-phosphate (PLP).

Increasing your intake of B6-rich foods is the first step for mild cases. For more significant deficiencies or those caused by underlying medical issues, a doctor may recommend and prescribe B6 supplements.