What are the symptoms of pyridoxal phosphate deficiency?

December 10, 2025 •

3 min read

According to the Centers for Disease Control (CDC), a marginal deficiency in Vitamin B6 is more common than overt deficiency and affects millions of Americans. This can lead to pyridoxal phosphate (PLP) deficiency, which is the active form of vitamin B6 and can significantly impact the body's systems, especially neurological, dermatological, and hematological functions.

Quick Summary

Pyridoxal phosphate deficiency can cause a variety of health issues, including neurological, dermatological, and hematological symptoms. This article details the key signs and causes of this nutritional imbalance to help individuals recognize potential issues.

Key Points

Neurological Issues: Pyridoxal phosphate deficiency can lead to peripheral neuropathy, characterized by tingling and numbness, and in severe cases, seizures and mood changes.
Skin and Oral Symptoms: A lack of PLP can cause seborrheic dermatitis, cheilosis (cracked lips), and glossitis (swollen, red tongue).
Anemia and Fatigue: The deficiency can result in microcytic anemia, leading to persistent fatigue and general weakness.
Weakened Immune System: An impaired immune response, making individuals more susceptible to infections, is another consequence of low PLP levels.
Causes Vary: While dietary causes are rare in developed countries, malabsorption issues, alcohol use, certain medications, and genetic disorders can all trigger a deficiency.
Toxicity vs. Deficiency: Interestingly, both a deficiency and an excess of vitamin B6 can cause peripheral neuropathy, highlighting the importance of proper dosage.

Understanding Pyridoxal Phosphate and Its Importance

Pyridoxal phosphate (PLP) is the active form of vitamin B6, an essential water-soluble vitamin. It acts as a crucial coenzyme in numerous metabolic processes, including amino acid, carbohydrate, and fatty acid metabolism. PLP is also vital for the synthesis of neurotransmitters, hemoglobin, and nucleic acids. A deficiency arises when the body has inadequate levels of this crucial compound, which can result from insufficient dietary intake or an underlying condition that affects absorption or metabolism.

Common Neurological Symptoms

Because PLP is essential for the production of neurotransmitters like serotonin, dopamine, and GABA, a deficiency often manifests with significant neurological symptoms.

Peripheral Neuropathy: A key neurological symptom is peripheral neuropathy, which can cause a "pins and needles" sensation, burning pain, and numbness in the hands, feet, arms, and legs. In severe cases, this can lead to clumsiness, poor coordination, and difficulty walking.
Mood and Cognitive Changes: Adults may experience confusion, depression, irritability, and anxiety. In severe cases, this can progress to disorientation and other cognitive issues.
Seizures: Seizures can occur, particularly in infants with an inherited metabolic disorder affecting PLP synthesis. These seizures may be resistant to conventional antiseizure medications but respond well to vitamin B6 supplementation.

Dermatological and Oral Manifestations

Skin and oral health are also significantly impacted by a lack of PLP, leading to distinct symptoms that can sometimes be mistaken for other conditions, such as pellagra.

Seborrheic Dermatitis: Individuals may develop seborrheic dermatitis, a scaly, red, and greasy rash that can appear on the face, scalp, and other areas.
Cheilosis and Glossitis: The mouth is often affected, with cheilosis (scaling and cracking at the corners of the mouth) and glossitis (a swollen, red, and smooth-looking tongue).

Hematological and Other General Symptoms

PLP is critical for the production of hemoglobin, the protein in red blood cells that carries oxygen. Its deficiency can therefore lead to anemia and other general health issues.

Microcytic Anemia: A deficiency can cause microcytic anemia, characterized by abnormally small and pale red blood cells, which leads to fatigue and weakness.
Weakened Immune System: PLP is needed for the production of antibodies and white blood cells, meaning a deficiency can impair immune function and increase susceptibility to infections.
General Weakness and Dizziness: General symptoms of weakness and dizziness are also commonly reported, resulting from the body's impaired energy utilization and cellular functions.

Comparison of Deficiency and Toxicity Symptoms

It is crucial to note that while deficiency causes issues, an excess of vitamin B6 can also lead to similar neurological symptoms, particularly peripheral neuropathy.


Symptom Category	Pyridoxal Phosphate Deficiency	Vitamin B6 Toxicity (Excess)
Neurological	Peripheral neuropathy (numbness, tingling), confusion, seizures.	Sensory neuronopathy (nerve damage), severe sensory loss, ataxia (poor coordination).
Dermatological	Seborrheic dermatitis, cheilosis, glossitis.	Some non-specific systemic symptoms like rashes may occur at very high doses.
Hematological	Microcytic anemia, fatigue.	Not typically associated with anemia; can cause hemolysis in some cases.
Gastrointestinal	Anorexia, vomiting, diarrhea.	Nausea, vomiting, diarrhea.

Causes of Pyridoxal Phosphate Deficiency

While dietary deficiency is rare in industrialized countries, several factors can increase a person's risk:

Malabsorption Issues: Conditions like celiac disease or inflammatory bowel disease can hinder the proper absorption of nutrients, including vitamin B6.
Alcohol Use Disorder: Excessive alcohol consumption can interfere with the body's ability to absorb and utilize B vitamins.
Certain Medications: Some medications, such as isoniazid used to treat tuberculosis, can interfere with PLP metabolism.
Inherited Metabolic Disorders: Rare genetic disorders, like pyridoxamine 5'-phosphate oxidase (PNPO) deficiency, impair the body's ability to synthesize PLP, leading to severe symptoms like seizures in infancy.

Conclusion

Pyridoxal phosphate deficiency is a serious condition that can affect multiple systems in the body, from the nervous system to the skin. Symptoms can range from general weakness and confusion to peripheral neuropathy and seizures. Recognizing these symptoms and understanding the potential causes, which include poor diet, malabsorption, and genetic factors, is crucial for timely diagnosis and treatment. Consulting a healthcare provider for a proper diagnosis and supplementation plan is the best course of action if a deficiency is suspected. Addressing the deficiency is critical to restoring proper metabolic, neurological, and immune function.

Frequently Asked Questions

Pyridoxal phosphate (PLP) is the biologically active coenzyme form of vitamin B6. It plays a critical role in over 100 enzymatic reactions in the body, primarily related to protein, carbohydrate, and fat metabolism.

While overt and severe deficiency is rare in developed countries, marginal deficiency is not uncommon. It is more prevalent in individuals with certain medical conditions, alcohol use disorder, or malabsorption issues.

Yes, a severe deficiency of PLP can cause seizures, particularly in infants with inherited metabolic disorders. These seizures may not respond to typical anticonvulsant medications but often improve with vitamin B6 supplementation.

Early signs can include peripheral neuropathy (tingling in hands and feet), mood changes such as irritability or depression, and skin issues like seborrheic dermatitis or cheilosis.

Excellent food sources of vitamin B6 include poultry, fish, organ meats, chickpeas, bananas, and fortified cereals.

Diagnosis typically involves a physical examination to identify clinical signs, a detailed patient history, and laboratory tests to measure serum levels of pyridoxal phosphate.

Treatment involves supplementation with vitamin B6. The dosage and duration depend on the severity and cause of the deficiency. It is important to address any underlying conditions, such as malabsorption.