NR (Nicotinamide Riboside) vs TUDCA (Tauroursodeoxycholic Acid)

Mechanism

NR is converted to NMN by nicotinamide riboside kinases (NRK1/NRK2), then to NAD+ via the salvage pathway. Like NMN, elevated NAD+ activates sirtuins, PARPs, and CD38. NR has demonstrated ability to cross the blood-brain barrier and elevate brain NAD+ levels. It supports mitochondrial function, DNA repair, and circadian rhythm regulation through SIRT1-mediated deacetylation of BMAL1 and CLOCK proteins.

Standard Dosing

300-600mg daily

Timing

Morning with or without food.

Cycle Duration

ongoing

Side Effects

• Mild nausea
• Warmth/flushing (mild)
• GI upset
• Fatigue in some during initial days

Contraindications

• Active cancer (same theoretical NAD+ concern as NMN)
• Pregnancy/lactation
• Theoretical cancer concern shared with NMN

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Mechanism

TUDCA is a water-soluble bile acid conjugate (taurine + ursodeoxycholic acid) with potent hepatoprotective and cytoprotective properties. It inhibits the mitochondrial pathway of apoptosis by preventing BAX translocation to mitochondria and cytochrome c release. TUDCA reduces endoplasmic reticulum (ER) stress by acting as a chemical chaperone, assisting protein folding and reducing the unfolded protein response (UPR). It protects hepatocytes by stabilizing cell membranes, displacing toxic hydrophobic bile acids (chenodeoxycholic, lithocholic) from biliary epithelium, and promoting choleresis (bile flow). Additionally, it has neuroprotective effects via reduction of ER stress in neurons and modulation of the TGR5 bile acid receptor.

Standard Dosing

250-500mg daily

Timing

With meals for liver support. Some protocols recommend before meals to prime bile flow.

Cycle Duration

Cycle 4-8 weeks for liver support; ongoing at low dose for chronic liver conditions under supervision

Side Effects

• Diarrhea (dose-dependent)
• GI discomfort
• Flatulence
• Rare: calcification of gallstones

Contraindications

• Complete biliary obstruction (cannot reach bile ducts if obstruction is complete)
• Calcified gallstones (UDCA/TUDCA dissolve cholesterol stones, not calcified)
• Acute cholangitis
• Complete biliary obstruction
• Gallstones (may mobilize stones)

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