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ALT

ALANINE AMINOTRANSFERASE (ALT)

Alanine aminotransferase (ALT) is an enzyme found most commonly in hepatocytes (the liver) and to a lesser extent the kidneys. Alanine aminotransferase also occurs in muscle cells, adipose tissue, the brain, and the prostate. The ALT enzyme catalyzes the transfer of amino groups from L-alanine to alpha-ketoglutarate, producing L-glutamate and pyruvate. This chemical process is crucial for the mitochondrial citric acid cycle. Elevated ALT levels usually indicate liver damage caused by various illnesses – as liver cells are damaged, alanine aminotransferase is released into the circulation. The ALT levels in hepatocytes are 3,000 times higher than in the blood.


ALT levels may also be elevated due to heavy exercise (up to a week afterward), alcohol use, hepatitis, celiac disease, certain medications (such as Paracetamol, statins, and opiate-based analgesics), and severe burns. Moderate increases in ALT levels also occur with metabolic disorders such as hyperlipidemia, obesity, and type 2 diabetes. In many countries, ALT levels are used to support the diagnosis of metabolic syndrome. An increase in the ALT levels is directly proportional to the occurrence and severity of metabolic syndrome – the higher the ALT levels, the more likely and severe the metabolic syndrome.


Extremely high ALT levels (10x the normal level) are usually caused by acute hepatitis. Elevated ALT levels are linked to increased mortality. Low ALT levels (below 10) are linked to higher mortality, particularly in the elderly. Low ALT levels may also occur in connection with impaired liver function.


Typical reference ranges (S-ALT):

  • Women: below 35 U/I
  • Men: below 50 U/I

Lifestyle factors decreasing (too high) ALT levels include:

  • Weight loss, if the individual is overweight
  • A hypocaloric diet (with a weight loss intent) in combination with cold-pressed olive oil will quickly reduce ALT levels in individuals with non-alcoholic fatty liver disease (NAFLD)
  • Relatively low-carbohydrate (below 35 % / “Mediterranean”) diet
  •  Reduces ALT levels regardless of whether weight loss occurs
  • A gluten-free diet (particularly for individuals with undiagnosed and/or untreated celiac disease)
  •  A person with celiac disease whose liver function levels (incl. ALT) are elevated will often find that these levels become normalized after a few months of consuming a gluten-free diet
  • Physical exercise (moderate intensity)
  •  Walking and basic aerobic exercise (particularly for individuals with non-alcoholic fatty liver disease or non-alcoholic steatohepatitis [NASH])
  •  Moderate-intensity strength training
  • Coffee (and caffeine) may inhibit the rise of ALT levels to some extent (more than 2 cups per day vs. no coffee)
  • Carotenoids from food reduce fatty liver disease and ALT levels
  •  For example, beta-cryptoxanthin and astaxanthin, as well as other carotenoids
  • Vitamin E as a dietary supplement, particularly for individuals with advanced fatty liver disease and slightly elevated ALT levels, as well as individuals with NAFLD, NASH, or CHC (chronic hepatitis C)
  • Resveratrol (500 mg/day) as a dietary supplement, particularly for individuals with advanced fatty liver disease
  • Powdered turmeric (3 g/day)
  • N-acetylcysteine (NAC; 600 mg x2/day), particularly for individuals with non-alcoholic fatty liver disease
  • Alpha-lipoic acid (400 mg/day) and ursodeoxycholic acid (300 mg/day), particularly for individuals with non-alcoholic fatty liver disease
  • Artichoke leaf extract (2,700 mg/day) as a dietary supplement, particularly for individuals with steatohepatitis or NAFLD
  •  Artichoke leaf extract may also improve blood cholesterol levels (see above)
  • Probiotic therapy may reduce liver enzyme levels across the board and promote recovery from non-alcoholic fatty liver disease
  • The mechanisms include reducing harmful bacteria, reducing small intestinal bacterial overgrowth (SIBO), regeneration of the intestinal lining, and immune system regulation

NB! Depending on the day and the situation, there may be significant biological variation in ALT values. Any elevated values should, therefore, be monitored with repeat tests, ideally at a few weeks.