Vitamin B6 is a water-soluble vitamin that your body uses as a helper molecule in over 140 different chemical reactions, most of them related to processing proteins and building brain chemicals. Adults need between 1.3 and 1.7 mg per day, and most people get enough through a varied diet that includes poultry, fish, potatoes, and bananas.
How Vitamin B6 Works in Your Body
Vitamin B6 actually refers to a group of six related compounds. The three natural forms found in food are pyridoxine, pyridoxal, and pyridoxamine. Once you eat them, your liver converts these into the active form called pyridoxal 5′-phosphate, or PLP. This is the version your cells actually put to work.
PLP acts as a cofactor, meaning it slots into enzymes and allows them to do their jobs. The vast majority of these enzymes work on amino acids, the building blocks of protein. That makes B6 essential for breaking down dietary protein, recycling amino acids, and building new molecules from amino acid raw materials. It also plays a role in releasing stored sugar from your muscles and liver for energy, and it helps your body make hemoglobin, the protein in red blood cells that carries oxygen.
The Brain Chemistry Connection
One of vitamin B6’s most important jobs happens in the brain. PLP is required to produce serotonin, dopamine, norepinephrine, epinephrine, and GABA. These are the neurotransmitters that regulate mood, motivation, stress response, and the balance between brain excitation and calm. Without adequate B6, your body simply cannot manufacture these chemicals at normal rates.
This is why low B6 levels have been linked to depression and confusion. The connection is biochemical, not speculative: the enzyme that converts the amino acid tryptophan into serotonin literally cannot function without PLP attached to it.
Vitamin B6 and Heart Health
Vitamin B6 works alongside folate (B9) and B12 to break down an amino acid called homocysteine. When homocysteine accumulates in the blood, it can damage artery walls and promote blood clots. Observational data suggests that every 5 µmol/L rise in homocysteine levels is associated with a 32% increased risk of heart disease and a 59% increased risk of stroke.
A meta-analysis of randomized controlled trials in stroke patients found that supplementing with B6, B9, and B12 together significantly lowered homocysteine levels and reduced the risk of recurrent stroke by 13%, with an 11% reduction in the combined risk of stroke, heart attack, and vascular death compared to placebo. The benefit appears strongest for stroke prevention rather than heart attacks specifically. That said, these results involved combination supplements, so it’s difficult to isolate B6’s individual contribution.
Signs of Deficiency
Vitamin B6 deficiency is uncommon in people who eat a varied diet, but it does occur, particularly in older adults, people with alcohol use disorders, and those taking certain medications that interfere with B6 metabolism. Deficiency affects multiple systems because the vitamin is involved in so many different reactions.
Early signs tend to be subtle: cracked and sore lips, a swollen tongue (glossitis), and a scaly rash, especially around the face. As deficiency progresses, neurological symptoms appear. These include confusion, depression, weakened immune function, and peripheral neuropathy, a tingling or numbness in the hands and feet. Because B6 is needed to make hemoglobin, prolonged deficiency can also cause a specific type of anemia where red blood cells are smaller than normal.
Recommended Daily Amounts
Your B6 needs increase gradually with age. Children ages 1 to 8 need 0.5 to 0.6 mg daily. By the teen years, the recommendation rises to 1.2 to 1.3 mg. Most adults ages 19 to 50 need 1.3 mg per day regardless of sex.
After age 50, requirements diverge slightly: men need 1.7 mg and women need 1.5 mg daily. Pregnant women need 1.9 mg, and breastfeeding women need 2.0 mg. These are relatively small amounts, and a single chicken breast or a cup of chickpeas can cover most of a day’s requirement.
Best Food Sources
Vitamin B6 is widely distributed across both animal and plant foods, which is one reason deficiency is relatively rare. The richest sources include:
- Poultry and fish: Chicken breast, turkey, tuna, and salmon are among the most concentrated sources, often providing 0.5 mg or more per serving.
- Starchy vegetables: Potatoes and sweet potatoes are surprisingly good sources, especially when baked with the skin on.
- Legumes: Chickpeas stand out as one of the best plant sources, with a single cup of canned chickpeas delivering roughly 1 mg.
- Fortified cereals: Many breakfast cereals are fortified with B6 and can provide a full day’s requirement in one serving.
- Bananas and other fruit: Bananas are the most commonly cited fruit source, though the amount per banana (around 0.4 mg) is moderate.
Because B6 is water-soluble, boiling foods can leach some of the vitamin into the cooking water. Roasting, baking, or steaming preserves more of it.
Too Much B6: The Toxicity Risk
Unlike some vitamins where “more is better” holds loosely true, vitamin B6 has a well-established toxicity threshold. The tolerable upper intake level for adults is 100 mg per day. You cannot realistically reach this through food alone; toxicity is almost always caused by high-dose supplements taken over weeks or months.
The primary symptom of B6 toxicity is, ironically, the same peripheral neuropathy that deficiency causes: numbness, tingling, and loss of coordination in the hands and feet. This happens because excess pyridoxine can damage sensory nerve fibers. Cases have been documented at doses as low as 200 mg per day taken chronically, though most reports involve doses of 500 mg or higher. The neuropathy is usually reversible once supplementation stops, but recovery can take months.
Medication Interactions
Certain medications can deplete your B6 levels or be affected by B6 supplements. Isoniazid, a tuberculosis drug, is one of the most well-known examples. It directly interferes with B6 metabolism, and people taking it are typically given B6 supplements to prevent deficiency-related nerve damage.
On the other side of the equation, vitamin B6 can reduce the effectiveness of levodopa, a medication used for Parkinson’s disease, by accelerating its breakdown before it reaches the brain. This interaction does not apply when levodopa is combined with carbidopa, which is the standard formulation today, but it’s worth knowing if you take any form of levodopa. Oral contraceptives and some anti-seizure medications may also lower B6 levels over time, which is why healthcare providers sometimes recommend monitoring or supplementation for long-term users.