Thiamine (Benfotiamine) vs Vitamin B6 (P5P)

Mechanism

Benfotiamine is a lipophilic S-acyl derivative of thiamine with 5x greater bioavailability than water-soluble thiamine. Once absorbed, it is converted to thiamine pyrophosphate (TPP), the active coenzyme for pyruvate dehydrogenase (linking glycolysis to Krebs cycle), alpha-ketoglutarate dehydrogenase (Krebs cycle), branched-chain alpha-ketoacid dehydrogenase (BCAA metabolism), and transketolase (pentose phosphate pathway). Benfotiamine specifically activates transketolase, shunting glucose metabolites away from damaging AGE (advanced glycation end-product) formation pathways, hexosamine pathway, and PKC activation — the three major pathways of hyperglycemic damage.

Standard Dosing

150-300mg benfotiamine daily

Timing

With meals. Divide higher doses.

Cycle Duration

ongoing

Side Effects

• Generally very well tolerated
• Mild GI upset (rare)
• Skin rash (very rare)
• Garlic-like body odor at very high doses

Contraindications

• Rare thiamine allergy (more relevant to parenteral administration)

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Mechanism

Pyridoxal-5-phosphate (P5P) is the active coenzyme form of vitamin B6, required by over 150 enzymes. Key roles: transamination and decarboxylation of amino acids, serving as a cofactor for aromatic L-amino acid decarboxylase (converting 5-HTP to serotonin and L-DOPA to dopamine), glutamic acid decarboxylase (producing GABA), cystathionine beta-synthase (homocysteine transsulfuration to cysteine), serine hydroxymethyltransferase (one-carbon folate metabolism), glycogen phosphorylase (glycogenolysis), and aminolevulinic acid synthase (heme synthesis).

Standard Dosing

25-50mg P5P daily

Timing

Morning with food. Often included in B-complex.

Cycle Duration

ongoing

Side Effects

• Peripheral neuropathy at chronic doses >200mg/day (numbness, tingling)
• Photosensitivity
• Nausea
• Vivid dreams

Contraindications

• Levodopa monotherapy
• Doses >200mg/day chronically (peripheral neuropathy risk)

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