ASTU/L
Liver + muscle damage
Also known as: Aspartate Aminotransferase, SGOT
Typical optimal range
0–40 U/L
Many laboratories use a typical reference range of around 0–40 U/L, but exact cut-offs vary between labs and can differ slightly by sex and age, so always interpret your result against your own lab's reference interval. These figures are indicative — the range printed on your own lab report is the definitive one for your results.
Interpretation of liver enzyme results in primary care follows NICE guidance on non-alcoholic fatty liver disease (NICE guideline NG49) and general NHS laboratory guidance; your GP will use your full clinical picture alongside the result.
What is AST?
AST (Aspartate Aminotransferase, sometimes still labelled SGOT on older reports) is an enzyme found in the liver, heart muscle, and skeletal muscle. When any of these tissues are damaged or under stress, AST leaks into the bloodstream, causing levels to rise. Because it is present in several tissue types, it is less specific for liver disease than ALT, but measuring the two together gives clinicians a more complete picture of what might be going on.
What a high AST means
A raised AST is a signal that one or more tissues — most commonly the liver, but also heart or skeletal muscle — may be under stress or damaged; it is a prompt to investigate further rather than a diagnosis in itself.
- Liver stress or disease. Conditions such as non-alcoholic fatty liver disease (now called MASLD), alcohol-related liver disease, viral hepatitis, and certain medications can all raise AST. It is often elevated alongside ALT in these situations, and the ratio of the two values can help guide further assessment.
- Recent intense exercise. AST is released from skeletal muscle as well as liver, so heavy gym sessions, endurance sport, or any strenuous physical activity in the two or three days before a blood test can push AST above the reference range even in a perfectly healthy person. This is one of the most common reasons for a mildly raised AST in otherwise well individuals.
- Alcohol intake. Even moderate-to-heavy alcohol consumption in the days before a test can raise AST, and chronic high intake is a well-established cause of persistently elevated levels. UK Chief Medical Officers advise keeping alcohol to no more than 14 units per week, spread across several days.
Because AST reflects muscle as well as liver health, a raised result needs to be interpreted alongside ALT and, where appropriate, CK (creatine kinase) to help distinguish a muscle source from a liver source.
What a low AST means
A low AST result is not generally considered clinically significant and is not routinely acted upon.
Should I be worried?
A single mildly raised AST, particularly in someone who has exercised hard recently or had a few drinks, is very common and often resolves on its own. It becomes more meaningful if it is persistently elevated across repeat tests, if it is significantly above the reference range, or if it rises alongside other liver markers such as ALT, GGT, or bilirubin. If your result is flagged as high, it is worth having a conversation with your GP — they may suggest repeating the test after a period of rest from intense exercise and reduced alcohol, and might check other markers such as ALT, GGT, ALP, and a full blood count to build a clearer picture. Try not to read too much into a single result in isolation.
What actually helps
If a raised AST relates to liver health or lifestyle factors, several evidence-backed habits can support the liver and help bring levels down over time.
- Reduce alcohol intake. Cutting back on alcohol is one of the most effective steps you can take if drinking is contributing to a raised result. Sticking within the UK Chief Medical Officers' low-risk guideline of no more than 14 units per week, with several alcohol-free days, gives the liver the chance to recover.
- Allow recovery time before testing. If you train regularly, it is worth scheduling blood tests at least 48–72 hours after your last intense session, since muscle-derived AST can remain elevated for several days after hard exercise and may otherwise give a misleading result.
- Achieve or maintain a healthy weight. Excess body fat, particularly around the abdomen, is closely linked to MASLD and raised liver enzymes. Even a modest, sustained weight loss of 5–10% of body weight has been shown in clinical studies to reduce liver enzyme levels meaningfully.
- Increase physical activity (moderate intensity). Regular moderate aerobic exercise — such as brisk walking, cycling, or swimming — improves insulin sensitivity and reduces liver fat over time, supporting healthier enzyme levels. The NHS recommends at least 150 minutes of moderate activity per week.
There is good supporting evidence that certain foods and dietary patterns benefit liver health and can help normalise raised liver enzymes.
Coffee (filtered or instant)
Multiple observational studies and meta-analyses have consistently linked regular coffee consumption with lower liver enzyme levels and reduced risk of liver disease; this effect is seen with both caffeinated and, to a lesser extent, decaffeinated coffee.
Oily fish (salmon, mackerel, sardines)
Rich in omega-3 fatty acids, oily fish has been shown in clinical trials to reduce liver fat in people with MASLD, which can help bring AST and ALT down over time.
Vegetables and legumes
A diet high in fibre from vegetables, pulses, and wholegrains supports a healthy weight and gut microbiome, both of which have knock-on benefits for liver fat and inflammation.
Nuts (especially walnuts)
Regular nut consumption is associated with lower liver enzyme levels in population studies, likely through anti-inflammatory and metabolic effects.
Olive oil
A core component of the Mediterranean diet, extra-virgin olive oil contains oleocanthal and other polyphenols with anti-inflammatory properties; the Mediterranean dietary pattern overall has evidence for improving liver enzyme profiles.
Wholegrains (oats, brown rice, wholemeal bread)
Replacing refined carbohydrates with wholegrains helps manage blood sugar and insulin levels, which in turn reduces the drive for liver fat accumulation associated with raised AST and ALT.
Track your own AST
Upload a lab PDF and Better Days trends AST over time, flags it when it drifts, and suggests foods that help.
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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.