GGTU/L
Liver detox load & alcohol exposure
Also known as: Gamma-Glutamyl Transferase
Typical optimal range
0–60 U/L
A typical optimal range is 0–60 U/L, though reference ranges vary between laboratories and by sex, so always interpret your result alongside your lab's own reference interval. These figures are indicative — the range printed on your own lab report is the definitive one for your results.
Interpretation of liver blood tests in UK practice follows NHS and NICE guidance, including NICE guideline NG49 on non-alcoholic fatty liver disease and NICE guideline CG141 on alcohol-use disorders, alongside laboratory reference standards published by the Association for Clinical Biochemistry.
What is GGT?
GGT (gamma-glutamyl transferase) is an enzyme found mainly in liver cells, with smaller amounts in the kidneys, pancreas, and bile ducts. It plays a key role in cellular antioxidant defence and the metabolism of glutathione. Because GGT leaks into the bloodstream when liver or biliary cells are stressed or damaged, measuring it in a blood test is a sensitive early indicator of liver stress — often rising before other liver enzymes do.
What a high GGT means
A raised GGT is a signal that the liver or bile ducts may be under stress and is worth investigating further — it is not a diagnosis in itself. Many causes are benign or reversible, and a single elevated result always needs to be interpreted in context.
- Alcohol intake. GGT is one of the most sensitive blood markers of regular alcohol consumption. Even moderate-to-heavy drinking over a short period can push GGT above the reference range; it typically falls back towards normal within two to four weeks of stopping or significantly reducing alcohol.
- Medications and supplements. A wide range of prescribed medicines — including statins, antiepileptics, antidepressants, and antibiotics — can raise GGT as the liver processes them. Some herbal supplements can have the same effect. Your GP can review your medication list if GGT is unexpectedly elevated.
- Fatty liver disease and biliary problems. MASLD (metabolic dysfunction-associated steatotic liver disease, formerly called NAFLD) and conditions affecting the bile ducts — such as gallstones or primary biliary cholangitis — are common causes of a chronically raised GGT, often alongside other abnormal liver markers.
GGT can be elevated even when other liver enzymes (ALT, AST, ALP) are still within range, which is why it is considered a particularly sensitive early marker. Strenuous exercise has little effect on GGT, unlike CK or AST, so exercise is not usually a confounding factor.
What a low GGT means
A low GGT result is not clinically concerning and does not require any action.
Should I be worried?
A mildly elevated GGT on a single test, particularly with no other liver markers out of range, is common and often has an entirely explainable cause — alcohol intake in the preceding weeks or a medication you are taking. It is worth tracking whether the value is rising, stable, or falling over time, which is exactly where repeat testing is useful. If your GGT is persistently raised, significantly above the reference range, or accompanied by elevated ALT, AST, or ALP, it is worth discussing with your GP. They may want to ask about alcohol intake and medications, arrange a repeat test, check other liver markers and a fasting lipid profile, and in some cases arrange an ultrasound scan of the liver — all straightforward next steps that can quickly clarify the picture.
What actually helps
If your GGT is raised, several well-evidenced lifestyle changes can help bring it down over time.
- Reduce alcohol. Cutting back on alcohol is the single most effective lever for most people with a raised GGT. Studies consistently show that GGT falls significantly within weeks of reducing or stopping alcohol, reflecting the liver's considerable capacity to recover.
- Review medications with your GP. If a prescribed medicine or supplement is thought to be contributing, your GP can weigh up whether an alternative is appropriate — never stop prescribed medication without discussing it first.
- Support a healthy weight. Excess weight — especially visceral fat — is a major driver of MASLD and raised liver enzymes including GGT. Even a modest, sustained weight loss of 5–10% of body weight can meaningfully improve liver markers, as supported by NICE guidance on fatty liver disease.
- Regular physical activity. Both aerobic exercise and resistance training have been shown to reduce GGT and improve liver health independent of weight loss, likely through reduced insulin resistance and hepatic fat content.
There is good supporting evidence for certain dietary patterns and foods in improving liver enzyme levels, including GGT.
Coffee (unsweetened)
Regular coffee consumption is consistently associated with lower GGT levels and a reduced risk of liver disease in epidemiological studies; the mechanism is thought to involve antioxidant and anti-inflammatory compounds including chlorogenic acids.
Cruciferous vegetables (broccoli, cauliflower, kale)
These vegetables contain glucosinolates and sulforaphane, which support the liver's detoxification pathways and have been linked to lower GGT in observational data.
Oily fish (salmon, mackerel, sardines)
Rich in omega-3 fatty acids, which have been shown in trials to reduce hepatic fat and improve liver enzyme levels in people with MASLD.
Wholegrains
A diet with a lower glycaemic load — supported by wholegrains over refined carbohydrates — helps reduce insulin resistance, a key driver of fatty liver and elevated liver enzymes.
Nuts (especially walnuts)
Regular nut consumption, particularly walnuts, is associated with better liver enzyme profiles, likely due to their anti-inflammatory fatty acids, polyphenols, and antioxidant content.
Berries and other polyphenol-rich fruits
Polyphenols found in berries, grapes, and other colourful fruits have antioxidant properties that may help reduce liver oxidative stress, which is one of the biological drivers of raised GGT.
Track your own GGT
Upload a lab PDF and Better Days trends GGT over time, flags it when it drifts, and suggests foods that help.
More in Liver
Sources & further reading
These are reputable UK health resources for further reading. This page is written to be consistent with their guidance but is not a substitute for them.
For information only — not medical advice, and not individually reviewed by a clinician. Reference ranges vary by lab and individual. Discuss any results with a qualified clinician before making changes.