Vitamin B6

What Is Vitamin B6?

Vitamin B6 is a group of six related, water-soluble compounds: pyridoxine, pyridoxal and pyridoxamine, and a phosphate form of each. Pyridoxine is the one in most supplements and the one in the name. The body turns all of them into pyridoxal 5'-phosphate (PLP), the form enzymes use.

What Vitamin B6 Does

PLP helps more than 100 enzymes, most of them breaking down, building or reshaping amino acids from protein. That is also how the brain gets its messengers: serotonin, dopamine, norepinephrine and GABA are all made from amino acids by B6-dependent enzymes. B6 is needed to build hemoglobin, which carries oxygen in red blood cells, and to turn the amino acid tryptophan into niacin.

With folate and vitamin B12, it also clears homocysteine, an amino acid that builds up in the blood when any of the three runs short. Trials that gave the three vitamins together lowered homocysteine, but did not reduce heart attacks or strokes.

Vitamin B6 in Garlic, Chicken, and Potatoes

Per 100 g, garlic has 1.235 mg of vitamin B6 in the Caltide food library, more than chicken. But a clove weighs about 3 g and gives about 0.04 mg, around 3% of what an adult needs a day. A 135 g portion of grilled chicken breast (0.855 mg per 100 g) gives about 1.15 mg, most of the 1.3 mg adults under 50 need, and a 28 g handful of pistachios about 0.48 mg.

Starchy plants count more than they look. A boiled potato has 0.3 mg per 100 g, so a 200 g potato gives about 0.6 mg, and a banana (120 g) about 0.25 mg. In the United States, fortified cereals, beef, poultry, starchy vegetables and some fruit supply most of the B6 people eat.

Who Is Most Likely to Be Low in Vitamin B6

Deficiency from diet alone is uncommon, and it usually comes with low folate and B12. The groups most at risk are people with kidney disease, including those on dialysis, people with autoimmune conditions such as rheumatoid arthritis, and people with alcohol use disorder. Signs include a type of anemia with small red blood cells, a scaly rash, cracks at the corners of the mouth, a swollen tongue, depression and confusion.

Too Much Vitamin B6 From Supplements

Vitamin B6 is one of the few B vitamins where too much does real harm. Months of high doses from supplements can damage the sensory nerves, starting with numbness or tingling in the hands and feet. In 2023 EFSA lowered its adult upper limit from 25 mg to 12 mg a day. Because B6 is in multivitamins, B-complex products and many combination supplements, amounts from two or three products can add up past that limit without any one label looking high.