ALTU/L
Liver-cell damage
Also known as: Alanine Aminotransferase, SGPT
Typical optimal range
0–41 U/L
Female
Many laboratories consider values up to around 41 U/L as within the typical reference range, though exact cut-offs vary between labs and may differ by sex, so always interpret your result against the range printed on your own report. These figures are indicative — the range printed on your own lab report is the definitive one for your results.
Interpretation of abnormal liver blood tests in primary care follows NICE guideline NG183 (Non-alcoholic fatty liver disease) and associated NHS pathway guidance; your GP will apply these alongside local laboratory reference ranges.
What is ALT?
ALT (Alanine Aminotransferase, sometimes called SGPT) is an enzyme found in high concentrations inside liver cells. When liver cells are damaged or inflamed, they release ALT into the bloodstream, causing levels to rise. Because it is more specific to the liver than other routine liver enzymes, it is one of the most useful early signals of liver stress — though it always needs to be interpreted alongside other tests and your clinical picture.
What a high ALT means
A raised ALT is a signal that liver cells may be under stress — it is not a diagnosis in itself, but it is a prompt to look more closely at what might be driving it. Most causes are common and addressable, and a single mildly elevated reading is often the starting point for a straightforward investigation.
- Metabolic-associated fatty liver (MASLD). Excess fat accumulating in the liver — closely linked to central obesity, type 2 diabetes, and raised triglycerides — is the most common reason for a mildly or moderately raised ALT in the UK. It is often picked up incidentally and, in its early stages, is frequently reversible with lifestyle change.
- Alcohol. The liver processes alcohol, and regular or heavy intake is a very common cause of raised ALT. Even amounts that feel modest can contribute, particularly if other risk factors are present. Being honest with yourself about weekly units is an important part of understanding your result.
- Medications, supplements, and other causes. A wide range of prescribed medicines (including statins, some antibiotics, and anti-inflammatory drugs), herbal supplements, viral hepatitis (B and C), and intense exercise causing muscle breakdown can all elevate ALT. Your GP will review your full medication and supplement list as part of any investigation.
Intense or unaccustomed exercise can temporarily raise ALT due to muscle cell breakdown rather than liver damage — worth mentioning to your GP if you have recently trained heavily. A single mildly raised reading often normalises on repeat testing.
What a low ALT means
A low ALT level is not generally considered clinically significant and does not usually require investigation.
Should I be worried?
A mildly raised ALT on a single test is common and rarely an emergency, but it does deserve attention rather than being ignored. Your GP will typically want to repeat the test after a few weeks — often alongside other liver markers such as AST, GGT, ALP, and bilirubin, as well as a full blood count and possibly a fasting lipid and glucose panel — to build a clearer picture. How far it is above the reference range, whether it is rising, and what other markers show will all guide next steps. If your result is significantly elevated, or if you have symptoms such as jaundice, abdominal pain, or unexplained fatigue, do contact your GP sooner rather than waiting.
What actually helps
For most people with a mildly elevated ALT, the following lifestyle changes have the strongest evidence behind them.
- Reduce alcohol intake. Cutting back on alcohol is one of the most direct and effective ways to lower ALT when drinking is a contributing factor. The UK Chief Medical Officers' guideline is to keep intake below 14 units per week, spread over several days, with alcohol-free days each week.
- Lose visceral fat through diet and activity. Even a modest reduction in body weight — around 5–10% — has been shown in clinical studies to meaningfully reduce liver fat and bring ALT down in people with MASLD. A combination of a sustainable calorie deficit and regular moderate exercise is the most evidence-backed approach.
- Increase physical activity. Regular aerobic exercise reduces liver fat independently of weight loss, and resistance training may also be beneficial. NHS guidance recommends at least 150 minutes of moderate-intensity activity per week as a baseline target.
- Review medications and supplements. If a medicine or supplement could be contributing, your GP can weigh the risks and benefits of continuing it. Never stop a prescribed medication without discussing it first, but do bring a full list — including over-the-counter products and herbal remedies — to your appointment.
Several dietary patterns and specific foods have good supporting evidence for reducing liver fat and supporting healthy ALT levels.
Coffee
Moderate coffee consumption (around 2–3 cups per day, caffeinated or decaffeinated) is consistently associated with lower ALT levels and reduced liver inflammation in observational and intervention studies; the mechanism likely involves antioxidant and anti-inflammatory compounds.
Oily fish and omega-3 rich foods
Omega-3 fatty acids (found in salmon, mackerel, sardines, and flaxseed) have been shown to help reduce liver fat in people with MASLD in several clinical trials, though evidence on ALT specifically is mixed.
Vegetables and fibre-rich foods
A diet high in vegetables, legumes, and wholegrains supports a healthy gut microbiome and reduces overall metabolic burden on the liver; high fibre intake is associated with lower liver fat in population studies.
Nuts (especially walnuts)
Regular nut consumption is associated with better liver enzyme profiles in epidemiological data, likely through anti-inflammatory fats and polyphenols; walnuts in particular feature in Mediterranean diet studies showing liver benefit.
Mediterranean dietary pattern
Adherence to a Mediterranean-style diet — rich in vegetables, olive oil, fish, legumes, and wholegrains — is one of the best-evidenced overall dietary approaches for reducing liver fat and improving ALT in people with metabolic liver disease.
Limit ultra-processed foods and added sugar
High intake of fructose (particularly from sugary drinks) and ultra-processed foods drives liver fat accumulation; reducing these is a practical and evidence-backed step, particularly for people with MASLD.
Track your own ALT
Upload a lab PDF and Better Days trends ALT 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.