Vitamin B6, also known as pyridoxine, is a water-soluble nutrient that plays a broad role in maintaining overall health. It is not produced by the body and must be obtained through diet or supplements. This vitamin participates in numerous bodily processes, contributing to various aspects of physical well-being.
Understanding Healthy B6 Levels
A healthy B6 level is typically measured by assessing the concentration of pyridoxal 5′-phosphate (PLP) in the blood plasma, as PLP is the biologically active form of vitamin B6. For fasting individuals, a reference range for PLP is generally considered to be between 5 and 50 micrograms per liter (mcg/L) or 23-223 nmol/L.
Maintaining B6 levels within this range is important for proper bodily function. PLP acts as a cofactor for over 140 different enzyme reactions in the body. These reactions are involved in protein, fat, and carbohydrate metabolism, as well as the creation of neurotransmitters and red blood cells. Blood tests for PLP are commonly performed using specialized laboratory methods.
When B6 Levels Are Not Healthy
B6 Deficiency
When B6 levels fall below the healthy range, a deficiency can occur, though dietary deficiency is considered rare as the vitamin is found in most foods. Common causes of low B6 include certain medications, such as isoniazid and some anti-seizure drugs, or conditions that impair nutrient absorption like celiac disease, Crohn’s disease, and chronic kidney disease. Alcohol use disorder and severe malnutrition can also contribute to deficiency.
Symptoms of B6 deficiency can affect various body systems. Neurological issues may include peripheral neuropathy, characterized by numbness, tingling, or a “pins and needles” sensation in the hands and feet. Skin problems like seborrheic dermatitis, presenting as a red, scaly rash, and cheilosis, which causes cracked and sore lips, can also arise. Other signs include glossitis (a swollen, red tongue), irritability, confusion, and in some cases, seizures. Anemia, where the body lacks healthy red blood cells, can also develop due to B6’s role in hemoglobin formation.
B6 Toxicity (Excess)
Conversely, excessively high levels of vitamin B6, primarily from over-supplementation, can lead to toxicity. Symptoms are often observed with long-term intake of dosages above 250 mg/day, though toxicity can occur at lower doses.
The most recognized symptom of B6 toxicity is sensory neuropathy, which involves damage to the nerves. This can manifest as numbness, tingling, pain, or burning sensations, often in the hands and feet. Other potential symptoms include difficulty walking, muscle weakness, loss of coordination, heartburn, nausea, and sensitivity to sunlight. If these symptoms appear, stop B6 supplementation and consult a healthcare professional. Nerve damage may improve but can sometimes be permanent, so medical guidance is recommended for diagnosis and management.