Vitamin B6 – Function, Requirements, and Food Sources
Vitamin B6 is a water-soluble nutrient belonging to the B vitamin group. It is essential for the proper functioning of the human body, supporting the nervous system and influencing immune health. This vitamin is found in many common foods as well as in dietary supplements. What is vitamin B6 good for? Which foods contain it? How much vitamin B6 should you consume daily? What are the symptoms of deficiency, and can too much of it be harmful?
Table of contents
What is vitamin B6?
Vitamin B6, also known as pyridoxine, is a water-soluble nutrient classified as a B vitamin. It is absorbed from the digestive tract and must be supplied through the daily diet or, when necessary, in supplement form. It consists of six related compounds, all sharing a pyridine ring as their core structure. Vitamin B6 is stored in the liver, kidneys, muscles, and brain and is involved in more than 140 different biochemical reactions in the body.
The vitamin was first isolated in 1932 by a Japanese scientist working on vitamin B1 extracted from rice. A few years later, a Hungarian researcher described vitamin B6 as a substance that could prevent skin inflammation in rats. In 1938, it was isolated from yeast, and soon after, its synthetic form was produced.
Vitamin B6 - sources
Vitamin B6 is widely present in both plant-based and animal-based foods. The richest sources include:
- wheat bran and germ,
- buckwheat groats,
- brown rice,
- quinoa,
- whole grain cereals,
- walnuts and hazelnuts,
- poultry,
- garlic, ginger, chili peppers,
- salmon, mackerel, trout,
- pork,
- liver.
Other good sources include sunflower seeds, bananas, red bell peppers, white beans, avocado, spinach, and dried apricots. It can also be found in soy, tapioca, raisins, peas, and eggs.
Vitamin B6 - functions. What is it good for?
Vitamin B6 acts as a cofactor for over 100 enzymes involved in cellular processes, making it essential for proper enzymatic activity. It participates in amino acid metabolism and protein synthesis, as well as in the metabolism of fats, carbohydrates, and nitrogen compounds. It plays a role in magnesium absorption, supports glycogen breakdown into glucose for energy, and is involved in gluconeogenesis – producing glucose from non-carbohydrate sources.
It is essential for immune system function, contributing to the production of antibodies and regulating immune cell activity. Low active B6 levels may correlate with higher inflammation markers. In the nervous system, vitamin B6 helps produce neurotransmitters like dopamine, serotonin, and epinephrine, and supports proper muscle contractions.
Vitamin B6 is involved in hemoglobin synthesis, steroid hormone regulation, and the conversion of tryptophan to niacin. It also helps regulate homocysteine levels, reducing cardiovascular risks such as arterial damage, heart attack, coronary heart disease, and stroke. Studies also suggest it may lower blood pressure.
As an antioxidant, it helps neutralize free radicals, reduces oxidative stress, and slows aging processes. It may improve skin health, relieve PMS symptoms, regulate mood through GABA synthesis, and reduce nausea and vomiting.
Research also shows that low vitamin B6 levels may contribute to diabetes development, while diabetes itself can lower B6 levels. Supplementation may help lower blood glucose and HbA1c levels in people with type 2 diabetes.
Daily vitamin B6 requirements
Recommended intake varies with age, sex, and physiological state. According to the Institute of Food and Nutrition (IŻŻ) guidelines, the Recommended Dietary Allowance (RDA) is:
- 0.5 mg for children 1–3 years,
- 0.6 mg for children 4–6 years,
- 1.0 mg for children 7–9 years,
- 1.2 mg for boys up to 12 and girls up to 18 years,
- 1.3 mg for women up to 50 and males aged 13–50 years,
- 1.5 mg for women over 50,
- 1.7 mg for men over 50,
- 1.9 mg for pregnant women,
- 2.0 mg for breastfeeding women.
Vitamin B6 deficiency
Deficiency is rare due to its wide availability in foods. Causes include:
- malabsorption disorders (e.g., intestinal diseases),
- medications interfering with absorption,
- increased needs not met by diet,
- genetic factors,
- excessive excretion due to health issues.
Mild deficiencies may cause no symptoms or slight disruptions in tryptophan and methionine metabolism. Severe deficiency may lead to:
- fatigue and general weakness,
- low mood, irritability, and nervousness,
- mouth corner cracks, eczema, inflamed tongue,
- skin and oral inflammation,
- weakened immunity,
- insomnia,
- neurological issues due to low GABA synthesis.
Vitamin B6 excess
Being water-soluble, excess vitamin B6 is excreted in urine and sweat. However, very high, long-term intakes may cause neurotoxic effects, including peripheral nerve inflammation.
Overdose symptoms may include:
- sensory and motor disturbances,
- muscle weakness,
- poor coordination,
- tingling or numbness in limbs,
- nerve tissue degeneration,
- persistent feeling of cold.
Vitamin B6 in supplements
Supplements can help people with deficiencies or higher needs – such as heavy drinkers, smokers, the elderly, malnourished individuals, athletes, and those under intense physical strain.
It is often found in B-complex products or combined with minerals like magnesium or zinc, but also available as single-ingredient products. Forms include tablets, capsules, drops, powders, and liquid shots.
Vitamin B6 - best form
It exists in six forms, derivatives of 4,5-bis(hydroxymethyl)-2-methylpyridin-3-ol, including pyridoxine, pyridoxal, pyridoxamine, and their phosphate esters. All are biologically active but are converted in the body to pyridoxal phosphate, the metabolically active coenzyme.
Supplements usually contain pyridoxine hydrochloride, which is stable under heat and light. However, pyridoxal-5-phosphate is considered the most bioavailable and active form.
Notably, using “pyridoxine” as a synonym for vitamin B6 is incorrect according to IUPAC-IUB biochemical nomenclature guidelines.
Vitamin B6 - possible drug interactions
It can interact with medications, with some improving and others impairing its absorption. Magnesium, zinc, and other B vitamins may enhance bioavailability. Increased needs occur with antiepileptic and antituberculosis drugs, as well as with L-dopa, theophylline, and benzodiazepines. Long-term NSAID use may also raise requirements.
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