KIN 343 - 11.21 Vitamin B6 - Overview, DRIs, and Sources

Overview of Vitamin B6

• Vitamin B6 comprises six vitamers, including three primary forms: pyridoxine, pyridoxal, and pyridoxamine.

• These vitamers are structurally related compounds that can interconvert into active forms needed as cofactors for enzymes.

• The phosphorylated derivatives of these compounds are:

  • Pyridoxine phosphate

  • Pyridoxyl phosphate

  • Pyridoxamine phosphate

• Phosphorylation traps these forms within cells, mainly seen in animals.

Dietary Reference Intakes (DRIs) for Vitamin B6

• Infants: AI is based on breast milk intake.

• Children: Increase in DRIs with age.

• Adults: RDAs for males and females can be similar but may differ by 100-200 micrograms.

• Pregnancy: Increased requirements to support maternal metabolism and fetal growth.

• Lactation: Even higher requirements than during pregnancy to ensure sufficient breast milk production.

Tolerable Upper Intake Level (UL) for Vitamin B6

• UL established for vitamin B6 due to potential toxicity from chronic elevated intakes.

• No UL determined for young infants; UL increases with age for both sexes.

• Excessive intake over time can lead to neuropathy.

• Commercial vitamin B6 supplements often contain around 100 milligrams per pill, which is at the UL.

Food Sources of Vitamin B6

Animal Sources

• Good sources include:

  • Salmon

  • Beef

  • Ham

  • Turkey

• Animal products predominantly contain pyridoxal phosphate and pyridoxamine phosphate.

Plant Sources

• Plants contain pyridoxine and the phosphorylated form pyridoxine phosphate.

• Whole grains are superior sources of vitamin B6 compared to polished grains due to the presence of husks and germ.

• Adequate amounts found in:

  • Vegetables

  • Fruits

• Vitamin B6 is more stable in the pyridoxine form, commonly found in commercial supplements.