Can yerba mate cause liver damage?

Can Yerba Mate Cause Liver Damage?

Yerba mate can cause liver damage, though this is rare, and you should discontinue it 2 weeks before surgery due to concerns for hyperglycemia and cardiovascular effects.

Evidence for Hepatotoxicity

The Society for Perioperative Assessment and Quality Improvement (SPAQI) recommends holding yerba mate for 2 weeks before surgery, citing concerns for hyperglycemia and cardiovascular effects, and noting the need to consider weaning due to dependence 1. While this guideline focuses on perioperative management, it acknowledges potential systemic effects that warrant caution.

There is one documented case report of acute hepatitis directly attributed to yerba mate consumption 2. This represents the first written case of mate tea-induced hepatotoxicity in the medical literature, demonstrating that idiosyncratic liver injury can occur 2.

Protective Effects vs. Risk

The evidence presents a paradox:

• Animal studies and in vitro research suggest hepatoprotective effects. Yerba mate improved metabolic redox status in rat liver, prevented oxidative damage, and reduced cell damage in histopathologic analysis 3. It has been described as hepatoprotective in comprehensive reviews 4.

• Human observational data shows protective associations. The beverage has been confirmed to show protective effects on liver cells in human studies 5.

• However, case reports document actual liver injury. The documented case of acute hepatitis proves that despite theoretical benefits, real hepatotoxicity can occur in susceptible individuals 2.

Clinical Decision-Making Algorithm

When evaluating a patient with elevated liver enzymes who consumes yerba mate:

1. Obtain detailed consumption history - document daily amount, duration of use, and preparation method (especially temperature, as very hot consumption may increase risk) 5, 2

2. Check the pattern of liver injury - determine if hepatocellular (elevated ALT/AST), cholestatic (elevated ALP), or mixed pattern 6

3. Rule out other causes systematically:

   • Viral hepatitis serologies 1
   • Alcohol use (detailed quantity assessment) 1
   • Other hepatotoxic medications or supplements 6
   • Muscle injury as source of elevated AST (check CK level) 7

4. If yerba mate is the suspected cause:

   • Discontinue immediately if ALT/AST ≥3x upper limit of normal 6
   • Monitor liver enzymes within 48-72 hours after discontinuation 6
   • Expect improvement if yerba mate was the culprit

Important Caveats

The risk appears idiosyncratic, not dose-dependent. Unlike acetaminophen, there is no established toxic threshold 1, 2. This means even moderate consumption could theoretically cause injury in susceptible individuals.

Very high consumption, especially when very hot, may increase cancer risk, though this has not been unequivocally confirmed 5. The temperature of consumption appears to be a modifying factor for multiple adverse effects.

Fungal contamination is a separate concern. Studies found substantial fungal growth in commercially available yerba mate samples, with some fungi surviving extreme pH and temperature variations 8. Immunocompromised patients face additional risk of invasive fungal disease from contaminated products 8.

Practical Recommendations

• For patients with known liver disease: Advise caution or avoidance, as pre-existing liver dysfunction reduces drug metabolism capacity and increases vulnerability to hepatotoxins 6

• For surgical patients: Discontinue 2 weeks preoperatively and consider tapering due to caffeine dependence 1

• For healthy individuals: While population-level risk appears low, counsel that rare idiosyncratic hepatotoxicity can occur and to discontinue immediately if symptoms develop 2

The contrast between animal studies showing hepatoprotection and human case reports of hepatotoxicity highlights that individual susceptibility varies considerably, and clinical vigilance is warranted despite generally favorable safety data 5, 2, 4, 3.