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GGT

GAMMA-GLUTAMYL TRANSFERASE (GGT)

Gamma-glutamyl transferase (GGT) is an enzyme found mostly in the liver, but also in the kidneys, pancreas, and intestine. The main function of GGT is the breakdown and recycling of glutathione. GGT is also involved in the breakdown of many drugs and toxins, forming amino acids and converting inflammatory molecules into other molecules.

Elevated GGT levels occur predominantly in connection with liver diseases (hepatitis or cirrhosis), but also with heart failure, stroke, atherosclerosis, diabetes, anorexia, hyperthyroidism, cancer, or pancreatitis. The most common cause of high GGT values is alcohol abuse. Even small amounts of alcohol can increase GGT levels.


Elevated GGT levels also occur in approximately half of all cases of non-alcoholic fatty liver disease (NAFLD, see above). In such cases, the levels are 2–3 times compared to normal. Many drugs can also increase GGT levels. These include anti-inflammatory drugs (NSAIDs), statins, antibiotics, antifungals, SSRIs, and H2 blockers. Environmental toxins can also increase GGT levels. Elevated GGT levels are linked to increased mortality. Low glutathione levels may also increase GGT levels, indicating that GGT levels indicate cellular level oxidative stress. Low GGT levels typically only occur in connection with familial intrahepatic cholestasis.


Elevated GGT levels are an independent risk factor for type 2 diabetes (along with ALT) and an early predictive marker of atherosclerosis, heart failure, arteriosclerosis, gestational diabetes, and various liver diseases.


Alcohol-induced increase in GGT levels may be controlled with carotenoid-based antioxidants such as lycopene, alpha- and beta-carotene, and beta-cryptoxanthin. According to researchers, GGT may be an early sign of oxidative stress in the body. The active form of ubiquinone, Ubiquinol (150 mg/day), significantly reduces oxidative stress and GGT levels.


Typical reference ranges (GGT):

  • Women: below 40 U/I
  • Men: below 60 U/I

Factors reducing GGT levels include:

  • Reducing alcohol use
  • Carotenoids and Ubiquinol (see above)
  • Avoiding heavy metals and insecticides as well as other pollutants
  • Drinking coffee (particularly for men who use alcohol)
  • Fish oil (a therapeutic dose, 4 g/day)
  • Curcumin and turmeric
  • The consumption of vegetables, berries, and fruits is linked to lower GGT levels