Val158Met COMT Polymorphism and Supplementation Guidelines

Introduction to Val158Met Polymorphism

The Val158Met polymorphism affects catecholamine metabolism, particularly dopamine clearance in the prefrontal cortex, with the Val/Val variant resulting in higher enzyme activity and faster dopamine metabolism, while Met/Met carriers have lower enzyme activity and slower dopamine clearance 1

The American College of Nutrition recommends choline supplementation for specific deficiency states, such as liver steatosis, parenteral nutrition patients, and cystic fibrosis, with dosing at 400-550 mg/day for general support and 550 mg-2 g/day for proven deficiency 3, 4, 6
The National Institutes of Health states that SAMe supplementation has limited evidence for most indications, with low certainty of evidence for major depressive disorder 2
The European Society for Clinical Nutrition and Metabolism recommends considering choline supplementation only when standard clinical indications exist, such as liver disease, nutritional deficiency, or specific metabolic conditions, independent of COMT genotype 3, 4, 7

The American Heart Association notes that choline can be converted to trimethylamine-N-oxide (TMAO) by gut bacteria, potentially increasing cardiovascular risk 3, 8
The National Academy of Medicine states that the upper limit for choline is 3.5 g/day, with high doses potentially causing hypotension and fishy body odor 3, 6, 7