Gamma-Glutamyl Transpeptidase (GGT)

Gamma-Glutamyl Transpeptidase (GGT)

Gamma-Glutamyl Transpeptidase (GGT) is an enzyme concentrated in the liver but also found in the bile ducts, kidneys, pancreas and spleen.  As one of the 3 main liver enzymes, it helps break down protein, moves molecules across the body and helps the liver break down toxins.  A blood test is used to check your liver enzymes and liver function. 


What is GGT and what do you need it for?

There are 3 main liver enzymes: 

  • Alkaline phosphatase (ALP)

  • Alanine transferase (ALT)

  • Gamma-glutamyl transpeptidase (GGT)

GGT helps to transfer amino acids across cell membranes and plays an important role in helping the liver metabolise toxins. 


Why is GGT an important biomarker?

Elevations of GGT are strongly related to increased liver damage, much more so than ALP and ALT markers, making it an important biomarker for liver health. It is also a sensitive marker of alcohol consumption.  If you drink in excess, your GGT levels usually increase. 

If your GGT levels are high as a result of liver damage, you may experience:

  • Jaundice - yellow skin and eyes

  • Itching

  • Nausea and vomiting

  • Tiredness

  • Unexplained weight loss

  • Swelling around the stomach or legs

More recently a new understanding of GGT has emerged beyond its traditional role as a marker of liver dysfunction, it is also regarded as a marker of oxidative stress. Therefore, it can be risk-associated with numerous conditions such as cardiovascular disease, diabetes, metabolic syndrome, cancer and all-cause mortality.  


How do I measure my GGT levels?

You can check your GGT levels and liver function with a blood test by a phlebotomist and you may wish to consult your doctor / medical professional about your results.

Optimal results are not precisely defined but ideally towards the lower end of the normal lab reference range:  

  • Biologically Male – Between 10-71 U/L (units per litre)

  • Biologically Female – Between 6-42 U/L

Although what is an 'ideal' vitamin D level remains contentious, around 75nmol/L is considered optimal for health.  

If you are not within an optimal range of GGT levels in your body, it is important to understand what could be causing this and what you can do to adjust your levels for better health.


What can influence my GGT levels?

  • Drugs - including antibiotics and Nonsteroidal anti-inflammatory drugs (e.g.g ibuprofen) can increase your levels.

  • Alcohol - the higher the alcohol intake often results in higher GGT levels.

  • Lower antioxidant defences - particularly glutathione is linked with higher GGT levels.

  • Iron overload - serum ferritin levels closely parallel GGT levels.

What can I do to impact my GGT levels?

Dietary and lifestyle modifications can help to lower raised liver enzyme levels caused by liver damage whilst tracking longer-term improvement in wider health markers such as cardiovascular health, iron status, metabolic health, inflammation and oxidative stress.  These can include: 

  • Reducing alcohol intake –to a low / moderate recommended level.

  • Food intake  – Eating a diet that bolsters the body's antioxidant defence system.

  • Enjoy coffee - coffee can help to lower GGT.

  • If there are signs of iron overload – An iron reduction strategy will be important to address with a medical professional. 

  • Boost levels of glutathoine – if they are low. 

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