Because of the toxic effects of food, water, and the environment, the liver can be a very busy organ, for humans as well as companion animals. Thorne Research Hepagen combines the beneficial liver herbs milk thistle and curcumin with antioxidants and important nutrients for phase I and II liver detoxification.

Pyridoxal 5'-phosphate acts as a cofactor for enzymes, catalyzes reactions with amino acids, and aids in the synthesis of nonessential amino acids. In this formula, the active form of vitamin B6, pyridoxal 5'-phosphate, is provided because healthy liver function is necessary of activation of vitamin B6. Vitamin B12 is required for proper digestion and absorption of food. It is also utilized in amino acid digestion as well as carbohydrate and fat metabolism.

Dimethylglycine (DMG) is a derivative of glycine, the simplest amino acid. It is a building block for many important substances, including methionine and choline. Methionine is an essential sulfur-containing amino acid necessary for phase II detoxification. It helps metabolize fats and is a precursor to cysteine and taurine synthesis. It can be converted to cysteine, a component of glutathione, an important endogenous antioxidant.

N-acetylcysteine (NAC) is composed of the amino acid cysteine and a sulfhydryl group, enabling it to interact with disulfide bonds. NAC serves as a nutritional precursor for the synthesis of glutathione. Reduced glutathione is an important endogenous antioxidant, essential for liver detoxification.

Silybum marianum (milk thistle) contains several potent flavolignans, including three structural isomers, silybin, silydianin, and silychristin, collectively referred to as silymarin. The antioxidant activity of silymarin appears to stabilize hepatocyte membranes, neutralize free radicals, and maintain liver glutathione levels. Curcuma longa has been used traditionally as a hepatoprotectant and cholegogue in both Chinese and Ayurvedic medicine. Its beneficial effects may be due to the fact that curcumin is a potent antioxidant and it helps maintain a normal inflammatory response.