Alanine aminotransferase is often used as a marker for liver health, with high levels indicating liver damage or disease. However, abnormally low levels are connected to some diseases, while factors beyond the liver can cause ALT to rise as well.

ALT is a very important marker to monitor, especially if you haven’t been leading the best lifestyle or you have chronic health issues. With Lab Test Analyzer you can track ALT levels and make sure they are always in the optimal range. Why wait until issues get out of hand and interfere with your work and daily life? Lab Test Analyzer has got you covered – it tracks your health and gives you actionable advice on how to improve it.

Keep reading to learn when you should be concerned about your ALT levels and ways to raise or lower it.

What Is ALT?

Alanine aminotransferase (ALT, also known as blood glutamatepyruvate transaminase, SGPT) is an enzyme necessary for breaking down food into energy for the body [R].

The majority of the body’s ALT is in liver cells. Small amounts are also found in muscle tissue and the blood [R].

When liver cells are damaged due to illness, injury, or medication, they release their stored ALT into the blood, increasing ALT blood levels [R].

Therefore, ALT blood levels (from here referred to simply as ALT levels) are interpreted as a marker for liver health: low levels typically indicate a healthy liver, while high levels suggest liver damage [R].

But sometimes, ALT levels remain normal despite a liver injury. Extremely low ALT levels, on the other hand, can signal other health problems [R, R].

ALT levels are also influenced by demographic factors and genetics [R].

Function of ALT

Muscles use amino acids for energy. ALT allows for the byproducts of amino acids to be transported from the muscles to the liver, where they are used to make glucose. This process is one of the body’s main ways of producing energy from food and consists of 2 steps (called the Cahill cycle) [R, R, R, R].

1) ALT Creates L-alanine to α-ketoglutarate in Muscles

In muscle cells, glutamate is a byproduct of burning proteins for energy, while pyruvate is a byproduct of burning glucose. ALT helps turn these into L-alanine and α-ketoglutarate [R, R].

L-alanine and α-ketoglutarate are then transported to the liver [R].

2) ALT Creates Pyruvate and Glutamate in the Liver

Once l-alanine reaches the liver, ALT transforms it into glucose for energy (via pyruvate), uses it to build new proteins (via L-glutamate), or eliminates it as waste (via L-glutamate) [R, R, R].

Once α-ketoglutarate reaches the liver, it is either used to make urea or as a source of energy (in another chemical process known as the Krebs cycle) [R].

ALT Levels

ALT is measured in units per liter of blood, or U/L.

Until recently, 10 to 40 U/L was accepted as the normal range, and this was used in most experiments to define “normal” versus “high” [R].

However, the most recent comprehensive review (107 studies reviewed in 2013) recommended that these values be revised due to ALT variation between the genders [R].

These researchers recommended that the upper limit of normal should be [R]:

  • 31 U/L for women
  • 42 U/L for men

ALT levels typically do not change much during pregnancy. It may slightly increase during the final trimester, but generally still remains below 40 U/L [R, R, R, R].

Blood Test for ALT

An ALT blood test may be ordered to [R, R, R, R]:

  • Assess liver health
  • Investigate symptoms of liver disease, such as abnormally yellow skin or eyes (jaundice), or pain in the upper-right section of the abdomen
  • Monitor progression of a liver disease
  • Evaluate the effectiveness of a treatment for liver disease
  • Determine if the liver is involved in or damaged by a health condition, such as diabetes or heart disease

You can request that your doctor test your ALT. Conventional doctors look at high or low ALT levels, often without mentioning anything. Sometimes, a lab result may be in the reference range, but not actually be in the optimal range. Reference ranges are not the same as optimal ranges. This is why even ALT in the ‘normal’ range can be unhealthy and indicate that certain processes in the body aren’t optimal. Lab Test Analyzer will let you know if your ALT levels are optimal and what you can do to get them there if they aren’t.

Since ALT is an enzyme, its level is typically determined by measuring its activity (the rate at which ALT transforms L-alanine and α-ketoglutarate into pyruvate and L-glutamate) [R].

ALT level is often measured together with the liver enzyme aspartate transaminase (AST). The ratio AST/ALT is also used as a marker of liver health.

While ALT levels can signal the presence of liver damage, they cannot determine the type of damage, such as scarring, infection, or inflammation [R].

Factors That Affect ALT Levels

Age

In a study with over 44,000 participants, ALT levels rose until age 60 in women and around age 45 in men, and then decreased [R].

In another study of 335 participants, ALT levels peaked around ages 40 to 55 for both genders [R].

In other studies, ALT levels decreased with ageing (2,364 participants; 1,489 participants; 335 participants) [R, R, R].

Adolescents are an exception, as they tend to have lower ALT levels than adults [R].

Gender

Men generally have higher ALT values than women, according to multiple large-scale studies (15,676 participants; 11,898 participants; 5,586 participants) [R, R, R].

In a study of 371 school children, boys had higher ALT levels than girls starting at 7 years old, indicating that hormones could account for the difference [R].

Genetics

Genetic variations between people of different ethnicities are most likely to influence ALT levels. However, in a study (meta-analysis) of 5,421 unrelated Dutch individuals, ALT levels were not significantly influenced by genetics, indicating that most genetic variation is likely between people of different ethnicities [R].

This conclusion is supported by research on Americans, who often have similar lifestyles and diets but come from a wide variety of ancestral backgrounds. For example, Mexican-Americans had higher levels of ALT (14.9%; 11.5%) than African- (8.1%; 6.0%) or white Americans (7.1%; 7.4%) in 2 studies with 15,676 adult and 5,586 adolescent participants [R, R, R, R].

In a study of 1,532 Mexican-Americans, 2 linked single nucleotide polymorphisms (SNPs) in the PNPLA3 gene (rs738409 and rs2281135) affected ALT levels. The combination C/T raised ALT levels, with G/C lowered ALT levels, and C/C had no effect. However, how strongly these SNPs impacted ALT levels varied by age and gender [R].

Other genetic variations that affect ALT are rare. In one case study, a newborn had extreme ALT deficiency due to mutations of liver cells (in the endoplasmic reticulum and mitochondria). Both parents must carry the mutation and pass it on their child for it to cause this disorder [R].

A 26-year-old Chinese man (case study) with liver failure and symptoms of malaise had ALT deficiency due to a mutation in the ALT gene itself [R].

In another case study, a woman had low ALT levels and hepatitis C, which typically presents with elevated ALT. Since her sons had low ALT levels as well, genetics were likely the cause [R].

Deletion of Aldh2 gene lowered ALT levels in response to alcohol consumption in mice [R].

Medication/Treatment

These medications and treatments have been shown to increase ALT levels in humans:

  • Anti-seizure medication (vigabatrin) [R, R, R]
  • Chemotherapy (immune checkpoint inhibitors, tyrosine kinase inhibitors) [R, R, R]
  • Anti-inflammatory medication (diclofenac; rofecoxib) [R, R, R]
  • Cholesterol medication (cholestyramine and rarely statins) [R, R, R, R, R, R, R]
  • Anti-obesity medication (rimonabant) [R]
  • Parenteral nutrition (nutrients delivered directly into the bloodstream, bypassing the digestive system) [R]
  • Antibiotics when multiple antibiotics are taken at once or they are taken for a long time [R, R]
  • Tylenol (acetaminophen) may cause a temporary ALT spike [R, R, R, R]
  • Asthma medication (Zileuton) in a small percentage of patients [R, R]
  • Antipsychotic medication (risperidone) in a very small percentage of patients [R, R, R]

These medications and treatments have been shown to reduce ALT levels in humans:

  • Hepatitis medication (telbivudine, lamivudine, ursodeoxycholic acid, dimethyl dicarboxylate, interferon) [R, R, R, R]
  • Hemodialysis [R, R, R]

Extreme Exercise (in the Short Term)

Strenuous exercise, as measured in 31 hockey players and 9 ultramarathon runners, immediately increased ALT levels [R, R].

In both studies, ALT levels decreased when the participants stopped exercising [R, R].

In a study of 20 Thai youths (ages 14 to 17), ALT levels significantly increased after a boxing match, but not during “intensive” training. This indicates that muscle damage is likely the cause of this ALT elevation, versus other biological effects of exercise [R].

Time of Day

In a study of 12 patients with liver damage (cirrhosis), ALT levels increased during the morning, peaked in the afternoon, and dropped to their lowest at night [R*].

However, in a study (RCT) with 22,970 participants, ALT values were not significantly different between the morning and afternoon. But, this study did not separately measure ALT by the hour or during the night [R].

* This experiment was published as a “To the Editor” letter and therefore was not peer-reviewed with the same scrutiny as the other experiments referenced in this article.

Conditions Associated with Low ALT

1) Heart Disease

Heart Disease

In multiple studies (meta-analysis of 29 studies with 1,264,380 million participants total), people with low ALT levels were more likely to suffer from heart disease [R, R, R].

Two studies of diabetic patients (9,795 and 2,993 participants) found similar results [R, R].

In the first study, people with ALT levels below 8 U/L were 65% more likely to suffer from a heart attack. In the second, the risk of heart disease began to decline for ALT levels over 30 U/L, especially in women [R, R].

Extremely low levels may indicate either impaired liver function or an underlying cause that is both reducing ALT and harming the heart [R].

2) Risk of Dying in Seniors

Risk of Dying in Seniors

In the elderly, low ALT levels may indicate an aging liver, increased fragility, and poor nutrition (455 participants, 1,673 participants) [R, R].

In a meta-analysis of 12 studies with 206,678 participants, extremely low ALT in elderly patients (less than 5 U/L) reliably predicted a risk of dying due to all causes, as well as from heart disease and cancer [R].

Furthermore, ALT may help the brain heal from stroke by helping cells recover from poor blood flow. This could explain why extremely low levels can be harmful [R].

3) Smoking

Smoking

People who smoked had lower levels of ALT in 2 studies with 17,515 and 5,946 healthy participants [R, R].

However, a study with 500 participants found the opposite trend—smokers had slightly higher ALT levels [R].

Smoking by itself may lower ALT levels while elevating ALT in people who already have certain types of liver disease [R].

For example, in a study of 6,095 patients with hepatitis, smoking further increased ALT levels in people that had hepatitis C, but not in those with hepatitis B [R].

4) Vitamin B6 Deficiency

In a 5-week study of 52 hemodialysis patients, low ALT levels were associated with vitamin B6 deficiency. ALT levels improved with daily B6 supplementation, indicating that ALT needs vitamin B6 for normal functioning [R].

5) HELLP Syndrome

HELLP syndrome is a disorder in pregnant women that causes malformed red blood cells, elevated liver enzymes, and platelets. A 28-year-old pregnant woman (case study) with high blood pressure, stomach pain, and pregnancy complications (due to newborn heart defects) had ALT deficiency due to HELLP syndrome.

How to Increase ALT

The research about increasing ALT levels is sparse. There are no drugs that are specifically designed for the task, since low ALT is typically seen as a good thing.

We highly recommend consulting a doctor if you are concerned about an abnormally low ALT level before trying any of the following interventions.

Eat More Sugar and Fat

Eat More Sugar and Fat

Supplementing the diets of 76 healthy men with sugar (fructose) for an average of 3 weeks increased ALT levels by an average of 5 U/L in a meta-analysis of 13 trials. Meanwhile, replacing carbs with sugar did not increase ALT levels in 184 healthy male participants [R].

A high-fat diet raised ALT levels in a post-menopause rat model [R].

However, these studies were testing diets to determine if they had a detrimental effect on the liver, which could be seen through increased ALT levels. These interventions are therefore not necessarily healthy ways to increase ALT [R].

Vitamin B6

In a 5-week study of 52 hemodialysis patients, low ALT levels were associated with vitamin B6 deficiency and were increased with daily B6 supplementation [R].

If on HemodialysisLose Weight

Lose weight

In a study of 146 patients with chronic kidney disease on hemodialysis, an average weight loss of 5% correlated with a 28% increase in average ALT levels [R].

Consume More Omega Fatty Acids

Soybean oil (combination of omega-6 and omega-3 fatty acids) and sunflower oil (omega-6 fatty acids) both increased ALT levels in rats [R].

Theoretically Gain Weight

Weight loss reliably reduces ALT, so weight gain may have the opposite effect [R].

It could be especially beneficial in the cases of seniors with extremely low ALT levels because it could improve fragility.

However, this hypothesis is purely theoretical and has not been tested in humans or animals.

High ALT Levels

Conditions Associated with High ALT

1) Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease

A non-alcoholic fatty liver disease is characterized by liver inflammation, fat buildup, and in extreme cases, severe, irreversible damage. It affects approximately 35% of the US population and often occurs alongside diabetes and obesity [R].

According to multiple reviews and studies (4,376 participants, 3,260 participants), a non-alcoholic fatty liver disease is the most common cause of mild ALT increase [R, R, R].

High ALT levels may also predict future development of non-alcoholic fatty liver disease In a study of 72 overweight adolescents, 32% of those with high ALT also had abnormally high levels of liver fat [R, R].

However, not all patients with the non-alcoholic fatty liver disease have high ALT levels, nor can ALT level be interpreted as disease severity [R, R].

In a study of 390 patients with a non-alcoholic fatty liver disease, 43% had normal ALT levels, though there was no difference between them in inflammation. In a study of 101 patients with a non-alcoholic fatty liver disease, those with normal and elevated ALT levels had equal disease severity and were equally at risk for developing further complications [R, R].

2) Alcohol Consumption

Alcohol Consumption

Alcohol consumption is the most common cause of liver disease in the Western Hemisphere [R].

In multiple studies from around the world (1.1 million Korean participants, 46,775 English men, 17,515 Americans, 6,832 Americans, 5,946 Koreans, 125 Italians), ALT levels increased with daily alcohol consumption [R, R, R, R, R, R].

Alcohol breakdown takes a significant toll on liver health by causing free radical damage and increasing levels of inflammatory markers (TNF-α). Long-term, excessive alcohol consumption leads to liver cell death, releasing ALT from the liver into the bloodstream [R, R, R].

But, the relationship between ALT level and alcohol consumption is more complicated than that. In a study of 13,580 adults, drinking alcohol increased ALT levels more in overweight people, who already had elevated ALT, than it did in those with normal weight [R, R, R].

In a study of 6,095 patients with hepatitis, drinking alcohol further increased ALT levels in people that have hepatitis C, but not hepatitis B [R].

Furthermore, patients with a higher initial ALT level were more likely to experience severe alcohol withdrawal in a meta-analysis of 15 studies [R].

However, in a study of 273 Japanese participants, even those who drank up to 81 g of alcohol per day (about 6 drinks) there was only a minor increase in ALT. In 125 Italian participants, “moderate” alcohol consumption (≤ 4 drinks per day) did not increase ALT levels [R, R].

Limited drinking may not increase ALT levels in normal-weight individuals due to its ability to improve insulin sensitivity, which seems to reduce ALT (13,580 participants; RCT of 63 postmenopausal women) [R, R].

3) Hepatitis

Hepatitis infections were a leading cause of extremely high ALT levels in multiple studies (15,676 Americans, 3,260 Taiwanese, 1,645 Italians, 273 Japanese) [R, R, R, R].

In a study of 182 patients over 2 years, 12% of cases of extreme ALT elevation (greater than 1,000 U/l) were due to a hepatitis infection [R].

In a case study of a 4-year-old girl, autoimmune hepatitis was the cause of chronically elevated ALT levels even though she experienced no other symptoms [R].

However, in a study of 280 patients with hepatitis C who didn’t have symptoms, 17% had normal levels of ALT, and 45% had mildly elevated ALT levels (below 80 U/L) [R].

It is still unclear whether ALT levels are viable in evaluating infection severity [R, R, R].

In 2 studies of patients with type 1 autoimmune hepatitis (84 patients over an average of 6 years, 69 patients over an average of 8 years) high ALT levels signaled progression of the infection and predicted poor outcomes, including liver cancer or death [R, R].

However, in a meta-analysis of 9 studies with 830 patients with hepatitis B, about a fifth of the patients who had normal ALT levels had severe liver scarring (liver fibrosis) [R].

In another meta-analysis of 8 studies with 683 patients with hepatitis B, nearly half of the patients (48%) with relatively low ALT levels had advanced liver damage [R].

4) Diabetes

Diabetes

In a meta-analysis of 17 studies involving 60,359 participants, the risk of developing type 2 diabetes increased as ALT level increased [R].

In a 5-year study with 724 participants, elevated ALT levels predicted future development of diabetes in cases where BMI, fasting blood sugar, and family history did not [R].

ALT levels were also positively associated with prediabetes, the intermediate step between high blood sugar and diabetes (literature review) [R].

Those with high ALT levels also showed signs of diabetes, such as high fasting blood sugar, increased insulin resistance, and impaired glucose tolerance in a diverse population in 3 studies (15,676 adults, 1,847 adults, 886 adolescents) [R, R, R].

In a study of 2,087 Japanese participants, high ALT was also associated with low levels of adiponectin, a protein that helps maintain glucose levels[R].

High ALT levels also signal the development of diabetic complications (such as glucose toxicity or liver disease) and predict worse outcomes for patients [R, R, R].

In a study of 16,865 adults, high ALT levels were associated with death due to diabetic complications [R].

High ALT levels were common in a study of 115 children with type 2 diabetes. These children could be at a greater risk of developing non-alcoholic liver disease [R].

In a study of 56 patients with type 1 diabetes, those with high ALT levels were more likely to have high BMI, high fasting blood sugar, and increased levels of HbA1c. This marker indicates if blood sugar had been chronically elevated [R].

5) Obesity

Obesity and elevated ALT have been associated with multiple studies (1,168,355 million participants) [R, R, R, R, R].

Specifically, waist circumference and stomach fat more accurately predicted ALT than the standard measurement of body mass index (BMI), as seen in multiple studies (8,430 adolescents, 8,428 adults, 903 women, 175 children) [R, R, R, R, R, R].

Stomach fat has different implications than general obesity and often accompanies conditions such as diabetes and liver disease [R, R].

In a study of 290 obese patients, insulin resistance was associated with high ALT [R].

Therefore, obesity may not itself be increasing ALT but maybe another symptom of an underlying cause that is also increasing ALT levels [R, R, R].

6) Metabolic Syndrome

Metabolic syndrome describes a number of interconnected symptoms that increase the risk of heart disease, diabetes, and the risk of dying in general. These symptoms include high blood pressure, high cholesterol, chronic inflammation, stomach fat, and insulin resistance [R].

In a meta-analysis of 5 studies with 29,815 participants, a risk of developing metabolic syndrome increased by 14% for every additional 5 U/L of ALT in the blood [R].

In another study with 28,456 participants, people in the top quarter of ALT levels were 82% more likely to suffer from metabolic syndrome than those in the bottom quarter [R].

In 2 studies with 5,586 adolescent and 1,740 adult participants, high ALT levels were significantly associated with increased C-reactive protein levels (often high in people with metabolic syndrome). Liver inflammation may contribute to the chronic inflammation in patients with metabolic syndrome [R, R, R, R, R, R].

7) Iron Overload

High ALT levels were associated with abnormally high iron levels, which can cause liver damage, in multiple studies (15,676 participants, 13,605 participants, 959 postmenopausal women) [R, R, R, R].

High ALT and iron overload may be byproducts of an underlying condition. However, iron overload can itself damage the liver, further increasing ALT levels [R, R].

In a study with 3,455 participants, high ALT levels were associated with increased levels of the iron-regulating hormone hepcidin, indicating that the body could be trying to protect the liver from iron overload by releasing hepcidin [R].

In mice, increased iron in the blood caused inflammation, free-radical damage, and a buildup of scar tissue in the liver, resulting in high ALT levels [R].

Hemochromatosis

Hemochromatosis is a genetic disorder found mostly in Caucasians (1 in every 250), which reduces the body’s ability to properly process iron, causing it to build up in cells [R, R].

In a study of 100 patients with hemochromatosis, 65% had high levels of ALT [R].

Hemochromatosis causes iron overload by blocking the production of the iron-regulating hormone, hepcidin [R].

8) Muscle Disease or Injury

Due to the small amount of ALT stored in muscle cells, muscle injury and disease can also cause ALT to leak into the blood and raise levels [R].

In a study of 620 patients with inflammatory muscle disease (polymyositis or dermatomyositis), 43% had high ALT levels [R].

Almost 88% of patients with muscular dystrophy, an inherited disease where muscles weaken and waste away, had high levels of ALT in a study with 232 patients with the disorder [R].

In a study with 16 patients with various muscle injuries, extreme exercise and seizures increased ALT levels [R].

In certain types of muscle disease, the severity of damage can be tracked by measuring ALT levels [R].

In a study of 189 patients in the ICU with rhabdomyolysis, a condition where muscle breaks down rapidly, those with ALT levels above 1000 U/L were 46.2% more likely to die than patients with lower ALT levels [R].

ALT levels also mirrored those of creatine kinase, another marker of muscle damage, in a study of 85 patients with muscular disease (idiopathic inflammatory myopathy) [R].

9) Stroke

Stroke

In a meta-analysis of 29 studies with 1.23 million participants, high ALT levels moderately increased the likelihood of stroke [R].

In a study with 279,982 Asian participants, men with elevated levels of ALT were 74% more likely to suffer a stroke than men with low ALT, though this association was less prominent in women (60%) [R].

10) High Cholesterol and Other Blood Fats

ALT, LDL cholesterol, and triglycerides (the main type of fat found in the body) are often high together. This may be due to the effects of insulin resistance and fatty liver disease, suggesting that high cholesterol and ALT are caused by an underlying issue [R, R, R].

Meanwhile, people with high levels of ALT tend to have low levels of HDL cholesterol in multiple studies (77,191 participants) [R, R].

11) High Blood Pressure

High blood pressure

High ALT was strongly linked to increased blood pressure in 2 studies with 15,676 and 416 participants [R, R].

Out of 69 active NFL players, elevated ALT was more common in linemen, who also tended to have high blood pressure [R].

High blood pressure and ALT may be caused by other health problems. People with a non-alcoholic liver disease, type 2 diabetes, and metabolic syndrome generally have both high blood pressure and high ALT levels (27,769 participants, 96 participants) [R, R].

In a study where all 151 participants had a non-alcoholic liver disease, those with especially high ALT levels were more likely to have high blood pressure [R].

12) High Uric Acid

High levels of uric acid in the blood can cause gout and kidney stones [R].

In 2 studies (with 11,572 participants and 3,260 participants), those with high uric acid blood levels also had higher ALT levels [R, R].

A similar result was found in another study with 11,898 participants, but only in women [R].

High uric acid raised the risk for non-alcoholic fatty liver disease in a study with 3,768 participants [R, R].

13) Antioxidant Deficiency

High ALT was linked to low levels of antioxidants in 2 studies with 13,605 and 4,376 participants [R, R].

Specifically, the levels of carotenoids (alpha-carotene, beta-carotene, other carotenoids, beta-cryptoxanthin, lutein/zeaxanthin) and vitamin C were lower in patients with high ALT levels in the study with 13,605 participants [R].

In another study of 1,037 participants over 7 years, people with low levels of provitamin A (beta-carotene, beta-cryptoxanthin, and total carotenoids) were 70% more likely to develop elevated ALT than participants with high levels of these antioxidants [R].

Liver disease (specifically fat accumulation in the liver) was connected to low levels of antioxidants in 2 studies with 350 and 97 participants [R, R].

Carotenoids and vitamin E may help maintain liver health by [R, R]:

  • Improving insulin resistance
  • Reducing the activation of genes that cause cell death
  • Turning white blood cells into anti-inflammatory molecules (M1 macrophages)
  • Blocking damage (from the release of free radicals from the breakdown of fats)

14) Bile Disease

Bile disease describes conditions that affect bile secretion, which involves the liver, gallbladder, and pancreas [R].

In a study of 424 patients with inflamed gallbladders (cholecystitis), those without gallstones had moderately raised ALT levels (82.5 U/L), and those with gallstones had noticeably raised ALT levels (95 U/L) [R].

In case studies of 7 patients with gallstones, ALT levels were initially very high—greater than 1,000 U/L in 5 cases. ALT levels decreased as soon as the gallstones were removed, bile was able to drain normally again, and the patients did not liver damage [R, R].

Higher initial ALT levels in younger patients before gallstone removal predicted a quicker recovery [R].

Gallstones also cause pancreatitis by blocking the bile duct and forcing the bile back into the pancreas [R].

The ALT levels of patients with pancreas inflammation due to gallstones was 200 U/L on average, much higher than levels in patients in which the inflammation was caused by other factors (33 U/L), in a study of 543 patients [R].

In a study of 275 patients with pancreas inflammation, high ALT levels (greater than 150 U/L) accurately predicted 97% if the inflammation was due to gallstones [R].

However, in another study of 167 patients with pancreas inflammation, ALT levels could not predict gallstones. In a 9-year study of 239 patients who had their gallbladders removed to treat this condition, those who had normal ALT levels were more likely to develop pancreas inflammation again [R, R].

15) Celiac Disease

In a study of 140 patients with chronically elevated ALT that was not explained by liver disease, diabetes, or alcohol intake, 8.5% turned out to have the undiagnosed celiac disease [R].

Liver injury due to untreated celiac disease is called celiac hepatitis and is usually successfully treated with a gluten-free diet [R].

In 2 studies with 171 and 158 adults with the untreated celiac disease, 42 to 47% had high ALT levels. After eating a strict gluten-free diet, ALT levels normalized in 95 to 100% of these individuals [R, R].

However, in a study with 13,818 participants with celiac disease and 66,584 healthy controls, the celiac patients were 2 to 6 times more likely to suffer from other liver diseases [R].

This suggests that untolerated gluten might create long-term damage to the liver [R].

16) Not Enough Oxygen

Poor circulation, as well as sleep apnea and high altitude, can lead to hypoxia, meaning that cells are not getting enough oxygen [R].

A study of 182 patients with extremely high ALT levels over 2 years identified poor circulation as one common cause of extreme ALT elevation (greater than 1,000 U/L) [R].

In a study of 85 patients with liver disease, those with sleep apnea were more likely to have elevated ALT levels. In another study of 540 participants with sleep apnea symptoms, lower oxygen levels accurately predicted high ALT levels [R, R].

The body can respond to the lack of oxygen by creating more red blood cells to carry more oxygen. This raises hematocrit, a blood test that measures the percentage of red blood cells in the blood [R].

In a study of 1,242 healthy participants, hematocrit accounted for 3% of the variation in ALT levels, which was less than BMI and gender, but more than blood pressure and cholesterol [R].

Hypoxia can lead to damage and inflammation, while also reducing the liver’s ability to regenerate, by creating new blood vessels and connective tissue. This was tested in a rat model of sleep apnea: occasional hypoxia damaged the liver (by free radicals), which eventually became a full-blown non-alcoholic fatty liver disease [R, R, R].

The liver disease itself can also reduce oxygen in liver cells, creating a positive feedback loop that quickly degrades liver health [R].

17) Viral Infection

Viral Infection

In a meta-analysis of 11 studies with 2,086 dengue (a tropical virus carried by mosquitoes) patients, 52% of patients with dengue fever and 54% of patients with life-threatening dengue (hemorrhagic) fever had abnormally high ALT levels [R].

This is likely due to inflammation from the dengue virus that creates lesions on the liver, based on a study with 169 dengue patients [R].

In 41 patients with mononucleosis, ALT initially increased about 5-fold but returned to normal after 20 days [R].

High ALT may signal a strong infection. In a study of 353 dengue patients, those with very high ALT levels were more likely to spend more time in the hospital, experience kidney or liver failure, and die [R, R, R, R].

High ALT levels were also associated with high HIV activity (RNA levels) and a strong infection, in 2 studies of 2,365 and 440 HIV patients [R, R].

18) Drug Overdose

In a study of 93 patients admitted for cocaine intoxication, high ALT levels (>85 U/L) were associated with muscle damage, acute kidney failure, and death [R].

In a study of 1,254 methamphetamine-dependent patients, those with severely high ALT (>80 U/L) were 84% more likely to die, and those with moderately high ALT (>40 U/L) were 59% more likely to die than those with normal ALT levels [R].

19) Choline Deficiency

The liver stores and breaks down choline, requiring this nutrient for optimal health. Choline dietary sources include eggs, chicken, salmon, and almonds [R].

Choline deficiency can cause liver cell death and fat accumulation in the liver, eventually leading to liver disease and possibly liver cancer [R].

Rats with choline deficiency had significantly higher ALT levels than those that ate a choline-supplemented diet [R].

However, research in humans is still underway. In a study (RCT) of 15 patients receiving nutrition through an IV (parenteral nutrition), choline reduced ALT levels after 6 weeks. In a study (RCT) of 60 men (with different MTHFR variants), choline supplements (550 mg per day) did not reduce ALT levels but did prevent ALT from rising [R, R].

20) Pregnancy Complications

Pregnancy Complications

In a study of 430 pregnant women, those with unexplained high ALT—not caused by diabetes, liver disease, or alcohol consumption—were 82% more likely to develop pregnancy-induced diabetes, excluding obese mothers [R].

In a study of 323 pregnant women, those with high ALT during their first trimester were 80% more likely to have a larger than an average-sized baby (macrosomia)[R].

21) Cancer (in Asian Populations)

In a meta-analysis of 14 studies with 1.79 million participants, Asians with ALT levels in the top third were 65% more likely to develop cancer than those in the bottom third. No such link has been made in Europeans [R].

In a study of 782,632 Korean men, those with high ALT were 62% more likely to develop esophageal cancer and 60% more likely to die from it than men with low ALT levels [R].

22) Risk of Dying (in Asian Populations)

In a meta-analysis of 19 studies with 9.24 million participants, Asian participants in the top third for ALT levels were 43% more likely to die from any cause than those in the bottom third. However, this association was not seen in North America participants [R].

23) Depression

Depression

People with high ALT levels were more likely to have symptoms of depression (67% for minor and 76% for major depression) in a study with 5,984 subjects [R].

The inflammation that often accompanies high ALT levels and liver disease could also increase the likelihood of depression through immune signals to the brain [R, R].

24) Maybe Heart Disease

Low ALT is typically associated with increased likelihood of heart disease, but some researchers have found the opposite or no association at all [R].

A meta-analysis of 29 studies with 1.23 million participants found a slight positive association between ALT levels and heart disease in Asian populations but found the opposite in European and North American populations [R].

Liver diseases that raise ALT levels and risk of heart disease—such as non-alcoholic and alcoholic liver disease—often go undiagnosed in Asian populations, possibly explaining population differences [R, R].

High ALT levels also increased the likelihood of an enlarged heart in a pilot study of 151 patients with non-alcoholic liver disease [R].

In another study of 610 patients, those with coronary heart disease had an average of 230% more ALT in their blood than the healthy controls (independent of confounding factors such as alcohol consumption, high blood pressure, and elevated cholesterol)[R].

ALT was not significantly correlated with heart disease in 2 studies with 3,719 participants and 2,812 participants [R, R].

How to Lower ALT

Engage in Moderate Exercise

Engage in Moderate Exercise

Exercise significantly decreased ALT levels in 1787 participants (meta-analysis and 2 other studies) with liver disease. Individuals with high starting BMI were particularly likely to see a major decline in ALT [R, R, R, R, R].

Exercise most likely reduces ALT levels in children and teens as well. In a study of 2,844 adolescents, those with “low” fitness had higher ALT levels than those with “adequate” fitness, suggesting that improving fitness with exercise could decrease ALT levels [R, R].

Intense exercise, on the other hand, increased ALT levels in studies on boxers, hockey players, and ultra-marathon runners [R, R, R].

Lose Weight

In a 15-month study with 31 overweight patients, exercise and diet led to weight loss, which was directly correlated to decreases in ALT [R].

In a study (RCT) of 2,153 healthy participants, treatment with the diabetes drug metformin for 3 years lowered ALT levels. This effect was dependent on weight loss, indicating that metformin stimulated weight loss, which in turn lowered ALT levels [R].

While evidence of weight loss directly lowering ALT levels is sparse, losing weight may slow and even reverse liver diseases such as non-alcoholic fatty liver disease, supporting the hypothesis that weight loss improves liver health [R].

Eat a Low-Carb Diet (or Gluten-Free Diet)

While a low-calorie diet likely reduces ALT through weight loss, low-carb diets lower ALT levels independent of weight loss [R].

For example, in a study (RCT) of 259 overweight diabetic patients, those who ate a modified Mediterranean diet (35% carbs, 45% fat) had lower ALT levels after 6 months than those on the American Diabetes Association diet (50% carbs, 30% fat) [R].

Furthermore, in a study (RCT) with 52 overweight, insulin-resistant patients, the low-carb diet (40% carbs, 45% fat) lowered ALT levels more than the low-fat diet (60% carbs, 25% fat) even though both diets had the same number of calories and participants lost the same amount of weight [R].

However, in a study of 59 obese women, participants on the low-fat and low-carb diets saw a similar reduction in ALT levels (33% and 41%, respectively). Both groups also lost a comparable amount of weight (5.5% and 5.7%, respectively), indicating weight loss was probably the intervening factor [R].

In cases of an undiagnosed celiac disease, a gluten-free diet is likely the most effective way to lower ALT levels. In 2 studies with 171 and 158 patients with celiac disease, ALT levels decreased in 95 to 100% of individuals with high levels after eating a gluten-free diet for 6 months [R, R].

Consume More Vitamins and Antioxidants

Vitamins and antioxidants

High ALT levels may be due to abnormally low levels of vitamins and antioxidants in the blood, indicating that supplementing with them could be beneficial [R, R].

Antioxidants and vitamins may improve liver health and ALT levels by reducing oxidative damage and inflammation (turning white blood cells into the anti-inflammatory type) [R].

Vitamin E

In a 2015 meta-analysis of 5 studies (RCTs) with 401 patients with a non-alcoholic fatty liver disease, supplementation with vitamin E reduced ALT levels by an average of 29 U/L [R].

Vitamin E supplementation also reduced ALT levels in patients with a non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, and chronic hepatitis C, according to another meta-analysis of 8 studies with 119 patients with various liver diseases [R].

In a study (DB-RCT) of 247 patients with a non-alcoholic liver disease, 800 IU of vitamin E per day (approximately 530 mg) decreased ALT levels after 96 weeks of treatment and improved liver health (biopsy) [R].

However, this result has not been duplicated in experiments with children and adolescents [R, R].

Vitamin E did not significantly reduce the ALT levels of children with liver disease (non-alcoholic fatty liver disease) in a meta-analysis of 5 studies (RCTs) with 270 children participants [R].

In a study (DB-RCT) of 173 adolescents with a non-alcoholic fatty liver disease, daily supplementation with 800 IU of vitamin E for 96 weeks did not reduce ALT levels. However, the control group may have adhered to their protocol better than the treatment group [R].

Resveratrol

Resveratrol, an antioxidant found in the skin of grapes and blueberries, may reduce inflammation and cell death in the liver [R, R].

Several studies (DB-RCTs) with 50 and 60 non-alcoholic fatty liver disease patients found daily supplementation with resveratrol reduced ALT levels [R, R]:

  • 500 mg daily for 12 weeks reduced ALT levels by 32% on average [R]
  • 300 mg daily for 13 weeks reduced ALT levels by 18% on average [R]

Vitamin C (Alone and with Vitamin E)

Vitamin C significantly reduced ALT levels in rats exposed to pesticides (neutralizing free radicals) [R].

Vitamin C and vitamin E, alone and in combination, decreased high ALT levels due to copper poisoning in baby chicks [R].

Finally, a combination of vitamins C and E reduced ALT levels due to alcohol consumption by reducing free radicals in multiple studies on rats [R, R].

Choline

Choline is a B vitamin-like nutrient necessary for healthy liver function. It occurs naturally in eggs, chicken, salmon, and almonds [R, R].

In a study (RCT) of 15 patients receiving nutrition through an IV (parenteral nutrition), choline reduced ALT levels after 6 weeks [R].

Choline supplements also lowered ALT levels in rats [R].

However, a study (RCT) of 60 men, choline supplements (550 mg/day) did not reduce ALT levels but prevented ALT from rising [R].

Rutin

Treatment with rutin, an antioxidant found in citrus fruits, reduced ALT levels in rats after they had increased due to a high-calorie diet and daily alcohol consumption [R].

Daily supplementation with rutin protected rats from high ALT levels when they were fed a high-cholesterol diet (by reducing the damage caused by free radicals) [R].

Drink More Coffee

Drink More Coffee

In multiple studies (26,206 participants total), people who drank an average of at least 2 cups of coffee per day had lower ALT levels than those who did not [R, R, R].

In a study of 376 patients with hepatitis C over 12 months, those who drank coffee regularly were more likely to see a decrease in their ALT levels, or preserve their normal ALT levels [R].

However, in a study of 177 patients with scar tissue on their livers (liver fibrosis), daily coffee consumption did not lower ALT levels. However, the participants who drank at least 2 cups of coffee a day had lower levels of scarring (as measured by liver biopsy), suggesting that coffee was still improving liver health [R].

It is unclear if the beneficial effects of coffee are due to its antioxidant properties or by another mechanism. Caffeine is unlikely to be involved because green tea does not consistently reduce ALT levels [R, R, R, R].

Try Iron Reduction Therapy

A 3-month regimen of iron reduction therapy reduced ALT levels by an average of 38% in a study (RCT) with 33 patients with chronic hepatitis C [R].

Supplement with Plant Extracts

Artichoke Leaf Extract

Taking 2700 mg of artichoke leaf extract per day for 2 months reduced ALT levels by an average of 47% in a study (DB-RCT) of 60 patients with non-alcoholic liver disease [R].

Extract of Hammada Scoparia Leaf

The Hammada scoparia leaf is a traditional medicine from North Africa used to treat cancer, hepatitis, and obesity [R].

Daily supplementation with this extract protected rats from increased ALT due to alcohol consumption [R].

Extract of Piliostigma thonningii Plant

The Piliostigma thonningii plant is native to the tropical forests of Africa, where it is used to treat stomach aches, coughs, colds, inflammation, and snake bites [R].

Daily supplementation with this plant extract significantly lowered ALT levels in rats, possibly by decreasing insulin resistance [R].

Drink Alcohol in Moderation

Alcohol

Small amounts of alcohol may reduce ALT levels by increasing insulin sensitivity, reducing free radical damage, and/or reducing blood levels of uric acid [R].

In a study of 9,703 healthy Japanese men, moderate alcohol consumption (4 to 14 drinks per week) was associated with lower ALT levels [R].

Minimal alcohol consumption (1% of their water) significantly reduced ALT levels in rats fed a high-fat diet. Doubling the alcohol consumption to 2% weakened the effect [R].

To put this in perspective, it is equivalent to about 11 grams of pure alcohol per day for a human. A standard drink has 14 grams of alcohol.

Probably Not Omega-3

Due to the beneficial effects of omega-3 fatty acids on a non-alcoholic liver disease, many researchers suspected that they would also decrease ALT levels. However, the evidence does not support this claim [R, R].

Though some studies found a positive result, 2 meta-analyses (932 participants total) did not find any benefits of omega-3 supplements for ALT levels [R, R].

Limitations and Caveats

ALT is not a reliable measure for liver health. Normal levels may mask diseases or infections, and individual variation is high due to internal and external factors [R, R, R].

Another literature review determined that ALT levels can differ by as much as 10 to 20% from the same sample, indicating that testing needs to be standardized [R].

Finally, even fluctuation within the normal range can indicate potential problems [R, R].

Tests of other liver enzymes such as AST, ALP, and GGT can help create a more complete picture of liver health [R].

Irregular ALT Levels?

If you have not yet tested your ALT levels, I recommend that you ask your doctor to do it. If you already have your blood test results and you’re not sure what to make of them, check out Lab Test Analyzer. It does all the heavy lifting for you. No need to do thousands of hours of research on what to make of your various blood tests.

People don’t realize that their blood test results contain a gold mine of information that’s waiting to be unearthed. Unfortunately, not everyone has the time nor the inclination to sift through dozens of research papers.

It’s super-simple so that even if you don’t have any background in science, you will understand what your results mean and what you can do to get them in the optimal range.

Lab Test Analyzer gives you up-to-date scientific information about your lab results. In addition, you will get both lifestyle tips and natural solutions to help you optimize your health. You can also rely on our science-based Optimal Ranges to prevent potential health issues and maximize your overall well-being.

All of the content is backed by science and researched by a team of PhDs, professors, and scientists.

We’re all unique, so we deserve solutions that treat us that way.

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The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

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