Enzyme that indicates liver health
21 of 22 providers
Liver Function
fatty liver disease
ALT (Alanine Aminotransferase) is an enzyme found primarily in your liver cells. When liver cells are damaged or inflamed, ALT leaks into your bloodstream, making it one of the most specific and sensitive markers for liver cell injury.
Unlike other liver enzymes like AST (which is also found in heart and muscle tissue), ALT is highly concentrated in the liver, which makes it the most specific indicator of hepatocellular damage. This specificity makes ALT the go-to marker for detecting conditions like fatty liver disease, viral hepatitis, medication-induced liver injury, and other forms of liver inflammation.
ALT is typically measured as part of a comprehensive metabolic panel or liver function tests. While conventional reference ranges often extend up to 40-55 U/L, research shows that optimal levels for longevity and metabolic health are much lower, typically under 25-30 U/L for men and under 20-25 U/L for women.
| Range Type | Level | Significance |
|---|---|---|
| Optimal (Longevity) | Men:<25 U/L, Women:<20 U/L | Associated with lowest metabolic disease risk and optimal liver health. Studies show ALT below these levels correlates with reduced cardiovascular events, lower diabetes risk, and better overall longevity. This is the target range for health optimization. |
| Borderline Elevated | Men:25-40 U/L, Women:20-35 U/L | Often still within "normal"lab range but indicates early metabolic dysfunction or mild fatty liver. This range warrants lifestyle intervention, weight loss if overweight, and investigation of underlying causes. Retest in 3-6 months after implementing changes. |
| Moderately Elevated | 40-100 U/L | Indicates significant liver inflammation or damage. Common causes include NAFLD, alcohol consumption, viral hepatitis, or medication toxicity. Requires medical evaluation, liver imaging (ultrasound), and investigation of underlying cause. Consider checking AST, GGT, and hepatitis panel. |
| Severely Elevated | >100 U/L | Indicates acute or severe liver injury. Levels >1000 U/L suggest acute hepatitis (viral, drug-induced, or autoimmune) or ischemic liver injury. Requires immediate medical attention, comprehensive liver workup including viral hepatitis panel, autoimmune markers, and imaging. Very high levels (>10,000) can indicate acute liver failure. |
Mediterranean diet:Emphasize olive oil, fish, vegetables, whole grains. Studies show 5-10% weight loss can normalize ALT
Reduce refined carbohydrates and sugar:Limit fructose, high-fructose corn syrup, white bread, and sugary drinks
Increase protein intake:1.2-1.6 g/kg body weight supports lean mass during weight loss
Intermittent fasting:Time-restricted eating (16:8) or alternate-day fasting can improve fatty liver
Coffee:2-3 cups daily associated with lower ALT and reduced liver fibrosis risk
Aerobic exercise:150-300 minutes/week of moderate intensity (brisk walking, cycling, swimming)
Resistance training:2-3 sessions/week builds muscle mass and improves insulin sensitivity
High-intensity interval training (HIIT):Particularly effective for reducing liver fat
Exercise works even without weight loss:Physical activity independently improves ALT and liver fat content
Metformin:500-2000 mg daily (if diabetic or prediabetic) improves insulin sensitivity and may reduce liver fat
GLP-1 agonists:Semaglutide, liraglutide show significant benefits for NAFLD and ALT reduction
Berberine:500 mg 2-3x daily, natural insulin sensitizer with liver-protective effects
Optimize sleep:7-9 hours nightly;poor sleep worsens insulin resistance and fatty liver
Manage stress:Chronic stress elevates cortisol, which promotes abdominal fat and liver fat accumulation
Vitamin E:400-800 IU daily (mixed tocopherols) reduces ALT in NAFLD (works best if non-diabetic)
Omega-3 fatty acids:2-4g EPA+DHA daily reduces liver fat and inflammation
Milk thistle (silymarin):140-280 mg 2-3x daily supports liver regeneration
N-acetylcysteine (NAC):600-1200 mg daily boosts glutathione, a key liver antioxidant
Choline:550 mg daily (or phosphatidylcholine) prevents fat accumulation in liver
Limit or eliminate alcohol:Even moderate drinking (1-2 drinks daily) can elevate ALT and accelerate liver disease
Review medications:Statins, NSAIDs, antibiotics, and many supplements can cause drug-induced liver injury
Avoid excessive acetaminophen:Stay under 3000 mg/day;lower if drinking alcohol or taking other medications
Reduce toxin exposure:Minimize pesticides, industrial chemicals, and unnecessary supplements
Check for viral hepatitis:Test for Hepatitis B and C if ALT remains elevated despite lifestyle changes
Large population studies show that even ALT levels in the "high-normal"range (30-40 U/L) are associated with increased risk of liver disease progression, metabolic syndrome, and cardiovascular events. The optimal upper limit for ALT is likely 25-30 U/L for men and 20-25 U/L for women, much lower than conventional reference ranges.
Source:Prati D, et al. Updated definitions of healthy ranges for serum alanine aminotransferase levels. Ann Intern Med. 2002;137(1):1-10.
Meta-analyses demonstrate that elevated ALT independently predicts cardiovascular disease, stroke, and all-cause mortality. Each 5 U/L increase in ALT is associated with 15% higher risk of cardiovascular events. This relationship holds even after adjusting for traditional risk factors like cholesterol and blood pressure.
Source:Kunutsor SK, et al. Liver aminotransferases and risk of cardiovascular disease:A systematic review and meta-analysis. Atherosclerosis. 2014;236(1):12-20.
Randomized controlled trials show that 7-10% weight loss through caloric restriction and exercise significantly reduces ALT, liver fat content, and even reverses early liver fibrosis in NAFLD patients. The Mediterranean diet combined with exercise is particularly effective, with up to 45% of patients achieving ALT normalization.
Source:Vilar-Gomez E, et al. Weight loss through lifestyle modification significantly reduces features of nonalcoholic steatohepatitis. Gastroenterology. 2015;149(2):367-378.
Multiple large cohort studies show that regular coffee consumption (2-3+ cups daily) is associated with lower ALT levels, reduced risk of NAFLD progression to cirrhosis, and lower rates of liver cancer. Both caffeinated and decaffeinated coffee show benefit, suggesting compounds beyond caffeine (like chlorogenic acids) provide liver protection.
Source:Alferink LJ, et al. Coffee and herbal tea consumption is associated with lower liver stiffness in the general population. J Hepatol. 2017;67(2):339-348.
The PIVENS trial demonstrated that vitamin E (800 IU daily) significantly improved ALT levels, liver histology, and inflammation in non-diabetic patients with NASH compared to placebo. However, benefits are most pronounced in non-diabetics, and long-term safety requires monitoring.
Source:Sanyal AJ, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis. N Engl J Med. 2010;362(18):1675-1685.
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $349 | 100+ | |
 InsideTracker | ✓ | $680 | 54 |
 Function Health | ✓ | $365 | 100+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| — | $399 | 100+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $125 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 129 |
21 providers include this biomarker in their panels
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
