Those which bind to the B12-IF complex, preventing uptake, those which bind to IF itself, preventing the binding with B12, and those which bind to parietal cells, preventing the production of IF to begin with
Mechanism of Action and Target Biology NNMT Enzyme and Function: Nicotinamide N-methyltransferase (NNMT) catalyzes the SAM-dependent methylation of nicotinamide: Reaction: Nicotinamide + SAM 1-methylnicotinamide (1-MNA) + S-adenosylhomocysteine (SAH) Expression: Liver, adipose tissue (particularly visceral), smooth muscle, some neurons Regulation: Increased expression in obesity, diabetes, aging, certain cancers Substrates consumed: Nicotinamide (NAD+ precursor) and SAM (methyl donor) 5-Amino-1MQ Inhibition Mechanism: Competitive inhibitor with respect to nicotinamide substrate IC: Submicromolar range for NNMT enzyme Selectivity: Minimal inhibition of other methyltransferases at relevant concentrations Result: Increased intracellular nicotinamide availability for NAD+ salvage pathway Downstream Effects of NNMT Inhibition: 1
Two concentration targets dominate community documentation: 2.5 mg/mL and 5 mg/mL
Singapores HSA has issued warnings about this
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If the reaction happens within minutes of taking the supplement, it is more likely an acute allergic response
