Gamma-glutamyl transferase or Gamma GT (GGT) is an enzyme which is found mostly in the liver. The amount of GGT present in the blood increases if the liver is injured or there is an obstruction to the flow of bile. It is also increased by enzyme induction.
GGT is an enzyme which speeds up the transfer of functional groups of molecules such as glutathione to an acceptor which may be an amino acid, a peptide or water. Gamma-glutamyl transferase is found in the cell membranes of many tissues in the body such as the biliary cells, pancreatic and kidney cells. GGT is believed to help transport amino acids across cell membranes. However, it also hydrolyses glutathione and helps to protect against injury from oxidants.
Receiving low or normal GGT results are usually of no concern. However, high GGT can be an indication of liver damage. GGT can also be a marker for high alcohol consumption via induction alongside liver disease. In some studies, GGT levels have also been predictive of chronic conditions such as cardiovascular disease, heart failure, obesity, metabolic disorder and type 2 diabetes. This is due to the oxidant activity shown in people with high GGT. The pro-oxidant activity can cause cell damage as well as DNA damage and these are seen more often in people with chronic diseases.
In terms of liver damage, the higher the concentration of GGT, the more severe the damage to the liver is. High levels can be due to high alcohol consumption, heart failure or drugs. The symptoms of liver disease can greatly affect your life and may include severe fatigue, reduced hunger, nausea, diarrhoea, stomach pain and yellowing of the skin (jaundice). The physical features of liver disease such as jaundice can lead to low self-esteem and depression.
Leading a healthy lifestyle and making some lifestyle changes can help to improve/maintain GGT levels.
A diet which is high in natural foods such as fruit and vegetables are associated with lower blood GGT levels. Fruit and vegetables are a good source of vitamins, minerals and dietary fibre and are rich in antioxidants, so can have protective affects against DNA cell damage caused by high GGT levels.
In the developed world, alcohol is one of the three leading causes of liver disease alongside viral hepatitis. Therefore, it is important to keep your alcohol intake low and within safe limits. The government recommends that the public should drink no more than 14 units of alcohol per week.
Intense physical exercise can cause elevations of biomarkers used in liver function tests. However, this may not necessarily be the case for all biomarkers including GGT.
In adults who are overweight and who may also have fatty liver disease, exercise has been shown to have beneficial effects. Regular exercise can help to reduce the fat found in the liver whilst at the same time improving both cardiovascular and respiratory health.
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