Vitamin B6

Studies in people

• Open question

  Women's health and deficiency²

  Vitamin B6 deficiency is linked to health problems in women, and fixing it is thought to help.

• Open question

  Cancer risk³

  People who ate more vitamin B6 from food had lower cancer risk, but supplement trials found no such effect.

• Benefit

  Constipation risk⁴

  People who ate more vitamin B6 in food were less likely to report ongoing constipation.

• Benefit

  Stress and quality of life⁵

  In stressed adults with low magnesium, vitamin B6 plus magnesium improved physical activity in daily life more than magnesium alone.

• No harm found

  Stress levels in adults⁶

  In adults with low magnesium, vitamin B6 added to magnesium gave no extra stress relief overall.

• Benefit

  Dementia risk⁷

  In a long study of Japanese adults, those who ate more vitamin B6 were less likely to develop dementia.

• Open question

  Energy use during exercise⁹

  Vitamin B6 helps the body release energy during exercise, and some female athletes may not get enough.

• Concern

  Nerve damage risk¹⁰

  Vitamin B6 overdoses rose in people taking supplements, and high doses can cause nerve damage.

• Open question

  Bowel cancer risk¹¹

  Vitamin B6 in the blood has been linked to lower bowel cancer risk, but studies of B6 in food disagree.

• Benefit

  Birth control side effects¹²

  Women taking vitamin B6 pills reported less nausea, headache and depression while on the pill.

• Benefit

  Dietary vitamin intake and cancer¹³

  In women not taking supplements, higher dietary vitamin B6 intake was linked to lower colorectal cancer risk.

• Benefit

  Immune system in a rare disorder¹⁴

  People with common variable immunodeficiency often had low vitamin B6, and taking vitamin B6 raised their CD4 T cells.

• Benefit

  Leg artery disease¹⁵

  In older men, those eating more vitamin B6 were less likely to have narrowed leg arteries.

• Benefit

  Parkinson's survival¹⁶

  In people with Parkinson's, eating more vitamin B6 before diagnosis was linked to living longer.

• Open question

  Exercise performance¹⁷

  In men eating little vitamin B6, thiamin and riboflavin for 11 weeks, exercise performance dropped, but not because of any one vitamin.

Animal and lab studies only

• Benefit

  Colon cancer risk²⁰

  In animal studies, vitamin B6 in the diet cut down colon tumors in mice.

Study type not stated

• Open question

  Inflammation and cancer risk¹⁹

  Vitamin B6's link to inflammation and cancer is not yet fully understood.

How it’s made and used

• Kidney transplant nutrition⁸

  In children with kidney transplants, some had high vitamin B6 levels even without taking supplements.

• B6 supplements and blood¹⁸

  In six healthy people, taking vitamin B6 by mouth raised blood levels of several B6 forms, mainly pyridoxal-P.

• How much the body absorbs²¹

  In pig studies, 51 to 91% of vitamin B6 was absorbed from most foods tested, but only 16% from boiled brown rice.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.