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food source · 1
Bananas are often reduced to a potassium fruit, but their more reliable strength is vitamin B6: one medium banana supplies a good share of an adult's daily need.
Mechanism · A helper in the amino acid workshop
In the body, B6 becomes pyridoxal phosphate (PLP), which helps more than a hundred enzymes: it moves an amino group from one molecule to another, or clips one end off an amino acid to turn it into a messenger molecule. The last step in making several of the brain's neurotransmitters depends on it.
Numbers · Not the potassium champion
One medium banana supplies a good share of an adult's daily B6. Bananas do have potassium, about 358 mg per 100 g, but they are far from the top; potato with its skin has more by weight. A banana tastes sweeter as it ripens because its starch is turning into sugar, not because it gains B6.
synergy · 1
Homocysteine in the blood is managed by three B vitamins together: B12 and folate turn it back into methionine, and B6 sends it toward making cysteine. A shortage of any one of the three can raise homocysteine.
cofactor · 2
The active form of vitamin B6 (PLP) is the coenzyme for two key reactions: one takes a one-carbon unit off serine and hands it to folate, and the other sends homocysteine toward making cysteine. So in one-carbon metabolism, folate and B6 stand on two sides of the same junction.
What the body runs short of is never the amino group but the carbon skeletons of the 9 essential amino acids: transaminase enzymes constantly move amino groups from one molecule to another, and the coenzyme that does this work is pyridoxal phosphate (PLP), the active form of vitamin B6.
regulates · 1
Vitamin B6 has some evidence for easing premenstrual symptoms, but it is limited. It is also one of the few water-soluble vitamins that harms when overdone: taking more than 100 mg a day long term can cause peripheral neuropathy, meaning numbness and tingling in the hands and feet. Keep both the benefit and the risk in mind.