Does vitamin C (ascorbic acid) increase liver enzymes?

Vitamin C Does Not Increase Liver Enzymes in Normal Individuals

Based on current evidence, vitamin C does not increase liver enzymes in healthy individuals and may actually have protective effects on liver function. 1

Evidence on Vitamin C and Liver Enzymes

Clinical Guidelines and Recommendations

The European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines on liver disease specifically address vitamin C in relation to non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). The guidelines state:

• "Until further data regarding their efficacy are available, antioxidants (e.g. vitamin C, resveratrol, anthocyanin, bayberries) cannot be recommended to treat NAFL/NASH" 1
• This recommendation received a grade 0 (insufficient evidence) with strong consensus (100% agreement)
• Importantly, the guidelines do not indicate any concern about vitamin C causing elevation of liver enzymes 1

Potential Protective Effects

Rather than increasing liver enzymes, evidence suggests vitamin C may have protective effects on liver function:

1. In NAFLD patients, epidemiological studies have reported vitamin C intake below recommended daily allowance, suggesting an association between dietary habits, disease, and vitamin C deficiency 1

2. Recent research indicates that higher dietary vitamin C intake is associated with:

   • Improved glucose metabolism
   • Better liver function
   • Reduced plasma ferritin (a biomarker of iron accumulation)
   • Higher albumin levels 2

3. Experimental studies in animal models have demonstrated that vitamin C supplementation:

   • Can ameliorate liver enzyme elevations caused by hepatotoxic substances
   • May reduce oxidative stress in the liver
   • Can attenuate hepatotoxic injuries 3, 4

Vitamin C Dosing and Safety

• The Recommended Dietary Allowance (RDA) for vitamin C is 75 mg for women and 90 mg for men 5
• Australia and New Zealand have established a Suggested Dietary Target (SDT) of 220 mg/day for men and 190 mg/day for women to address chronic disease prevention 1
• China has adopted a Proposed Intake (PI) of 200 mg/day to raise plasma vitamin C concentrations to achieve saturation 1
• A Tolerable Upper Level has been set at 2 g based on gastrointestinal upset that sometimes accompanies excessive intakes 5

Clinical Implications

• For healthy individuals, vitamin C supplementation within recommended ranges does not appear to increase liver enzymes
• In contrast to concerns about liver enzyme elevation, vitamin C may actually help normalize liver function in certain conditions 4, 2
• In diabetic models, vitamin C has been shown to ameliorate biochemical parameters including liver enzymes 6

Potential Caveats and Considerations

• Individual responses to vitamin C supplementation may vary
• Extremely high doses (above the Tolerable Upper Level of 2g) may cause gastrointestinal upset but not liver enzyme elevation
• Patients with pre-existing liver conditions should consult with healthcare providers before starting any supplement regimen
• The bioavailability of vitamin C from supplements is comparable to food sources 1

In conclusion, current evidence does not support concerns that vitamin C increases liver enzymes in healthy individuals. On the contrary, adequate vitamin C intake appears to be associated with improved liver function parameters.