Home Biomarkers Vitamin B6

Vitamin B6

Vitamins Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Vitamins

Overview

Vitamin B6 refers to a group of chemically related compounds; the biologically active form measured in blood is pyridoxal 5'-phosphate (PLP). The test measures plasma PLP concentration to assess vitamin B6 status. Deficiency can impair amino acid and neurotransmitter metabolism and hemoglobin synthesis, causing symptoms such as peripheral neuropathy, irritability, dermatitis, glossitis, seizures, or microcytic/hypochromic anemia. Excess (usually from supplements) can cause sensory neuropathy. Levels vary with age, pregnancy (requirements increase), chronic alcohol use, renal or hepatic disease, inflammation, and certain medications—older adults and malnourished people are at higher risk of deficiency.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Vitamins - Symptoms: unexplained neuropathy, anemia, seizures, dermatitis or glossitis, or suspected malnutrition - Diagnoses/monitoring: vitamin B6 deficiency, monitoring high-dose supplementation or drug-induced deficiency - Reasons for abnormal levels: poor intake, malabsorption, alcoholism, renal or liver disease, certain drugs (e.g., isoniazid) - Biological meaning: low PLP indicates inadequate cofactor availability for neurotransmitter and hemoglobin synthesis; high PLP usually reflects excessive supplementation and neurotoxicity risk - Lifestyle/family: heavy alcohol use, very restrictive diets, high-dose supplement use, or family history of metabolic disorders affecting B6 metabolism

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Understanding Test Results

PLP <5 μg/L (<20 nmol/L): consistent with deficiency.
Associated with symptoms such as peripheral neuropathy, seizures (esp.
in infants), irritability, glossitis and microcytic anemia; common causes include poor dietary intake, alcoholism, malabsorption, isoniazid therapy, or increased requirements (pregnancy).
PLP 5–8 μg/L (20–30 nmol/L): borderline/insufficient consider dietary review, medication effects, inflammation or early deficiency.
PLP 8–50 μg/L (30–200 nmol/L): generally adequate status for most people; clinical correlation needed if symptoms persist.
PLP >50 μg/L (>200 nmol/L): often reflects high-dose supplementation or impaired clearance; sustained high levels have been linked to sensory neuropathy and should prompt review of supplement use and dose reduction.
Very high values are uncommon and warrant evaluation for excessive intake and possible toxicity.
Factors such as acute inflammation, low albumin, or renal disease can alter PLP independently of intake and should be considered when interpreting results.

Normal Range

5-50 μg/L OR 20-200 nmol/L

FAQs

Q: What is vitamin B6 good for?

A: Vitamin B6 (pyridoxine) is a cofactor for many enzymes, aiding amino acid, carbohydrate and fat metabolism. It supports neurotransmitter synthesis (serotonin, dopamine, GABA), healthy red blood cell formation and hemoglobin, immune function, and brain development. Adequate B6 helps regulate mood, lower homocysteine levels, and can ease pregnancy-related nausea and some premenstrual symptoms when used appropriately.

Q: What are symptoms of vitamin B6 deficiency?

A: Vitamin B6 deficiency can cause skin rashes, flaky or sore lips and tongue, and mouth ulcers. Neurological symptoms include numbness, tingling, burning or weakness in hands and feet, poor coordination, irritability, depression and confusion. It may also cause anemia, fatigue, weakened immunity, and in infants can trigger seizures or developmental delays.

Q: What is another name for vitamin B6?

A: Vitamin B6 is also called pyridoxine. It exists in three related forms—pyridoxine, pyridoxal, and pyridoxamine—with the biologically active coenzyme being pyridoxal 5′-phosphate (PLP). PLP is essential for amino-acid metabolism, neurotransmitter synthesis, and hemoglobin production. Dietary sources include meat, fish, whole grains, legumes, and fortified foods; supplements often list it as pyridoxine or pyridoxine hydrochloride.

Q: What foods are high in B6?

A: Foods rich in vitamin B6 include poultry (chicken, turkey), fatty fish (salmon, tuna), and organ meats (liver). Plant sources include chickpeas, lentils, potatoes and other starchy vegetables, bananas, fortified cereals, whole grains, nuts (especially pistachios) and seeds. Regularly including a variety of these particularly lean meats, legumes and whole grains helps meet daily B6 needs through diet.

Q: Who needs vitamin B6 the most?

A: People who most need vitamin B6 include pregnant and breastfeeding women (higher requirements), older adults (reduced absorption), people with malabsorption or chronic kidney disease, those with liver disease or alcohol dependence, individuals on certain medications (e.g., isoniazid, some anticonvulsants, oral contraceptives), and anyone with a very poor diet or metabolic conditions that increase B6 loss.

Q: What fruits are high in vitamin B6?

A: Fruits rich in vitamin B6 include bananas (one of the best fruit sources), avocados, and cantaloupe. Other good choices are watermelon, mango, papaya, kiwi, and dried fruits such as prunes and apricots. Regularly including these fresh or dried fruits in your diet helps boost B6 intake for metabolism, nervous-system function, and red blood cell production.