KIN 343 - 11.22 Vitamin B6 - Digestion and Absorption

Vitamin B6 Digestion and Absorption

Forms of Vitamin B6

• Vitamin B6 comprises three primary forms:

  • Pyridoxyl Phosphate

  • Pyridoxamine Phosphate

  • Pyridoxine Phosphate

Dephosphorylation Process

• Dephosphorylation: Critical for the digestion and absorption of Vitamin B6.

  • The vitamins must be converted from their phosphorylated forms before absorption.

  • This process is largely facilitated by the enzyme alkaline phosphatase found in the gastrointestinal tract.

Absorption Mechanism

• Absorption Types:

  • At typical intake levels, dephosphorylation is necessary for absorption.

  • However, at high intakes, there is evidence to suggest that phosphorylated forms of Vitamin B6 can be absorbed intact.

Knowledge Gaps in Understanding

• There is currently a lack of solid understanding regarding:

  • The exact mechanism of absorption, including the identity of the transporter involved.

  • The processes involved in transporting Vitamin B6 into the bloodstream from enterocytes.

• Uptake Efficiency:

  • The absorption process is relatively efficient, with uptake efficiency reported to range between 60% to 90%.

Conclusion

• While certain aspects of Vitamin B6 digestion and absorption are well understood, significant gaps remain, particularly regarding the mechanisms for transporter identity and dephosphorylated absorption efficacy.