The liver performs hundreds of metabolic functions including glucose and lipid metabolism, synthesis of clotting factors and albumin, detoxification of drugs, environmental toxins, and metabolic by-products, and conjugation and excretion of bilirubin, hormones, and other compounds. Its ability to perform these functions efficiently depends entirely on having adequate cofactors, which come from diet.
Phase I and Phase II Detoxification
Hepatic detoxification occurs in two phases. Phase I uses cytochrome P450 enzymes to oxidise, reduce, or hydrolyse compounds, rendering them more water-soluble and often more reactive. Phase II conjugates these intermediates with glucuronic acid, glutathione, sulphate, or glycine, making them water-soluble for excretion. Both phases require specific nutrients as cofactors. Phase I requires B vitamins, magnesium, iron, and zinc. Phase II requires glutathione precursors including cysteine, glycine, and glutamine, sulphur from cruciferous vegetables and alliums, and glucuronic acid from adequate carbohydrate metabolism.
Dietary Supports for Optimal Liver Function
- Cruciferous vegetables: glucosinolates from broccoli, cauliflower, and Brussels sprouts specifically induce phase II enzymes through Nrf2 activation
- Garlic and onions: allicin and organosulphur compounds support glutathione synthesis and phase II detoxification
- Coffee: consistent evidence for protective effects against liver fibrosis and non-alcoholic fatty liver disease; 2 to 3 cups daily is associated with lower liver enzyme levels
- Adequate protein from whole food sources: provides the amino acid substrate for phase II conjugation reactions
- Adequate hydration: water is required for the renal excretion of conjugated compounds after hepatic processing