Vitamin B6-Rich Foods and Liver Enzymes
While vitamin B6 is essential as a cofactor for AST and ALT enzyme function, there is no evidence that consuming foods high in vitamin B6 will lower elevated liver enzymes—in fact, B6 primarily affects how these enzymes are measured in laboratory assays rather than treating the underlying liver pathology causing the elevation. 1, 2
Understanding the Relationship Between B6 and Liver Enzymes
The connection between vitamin B6 and AST/ALT is fundamentally about enzyme measurement, not treatment:
- Pyridoxal-5'-phosphate (PLP), the active form of vitamin B6, serves as a coenzyme for both AST and ALT transaminase reactions 2, 3
- When B6 deficiency exists, laboratory measurements of AST and ALT may appear artificially low because the enzymes lack their necessary cofactor to function in the assay 2, 4
- Adding PLP to laboratory reagents increases measured AST and ALT values in B6-deficient individuals, but this reflects improved assay accuracy rather than worsening liver disease 2, 4
Why B6 Supplementation Won't Lower Elevated Liver Enzymes
The critical distinction is that B6 deficiency causes falsely low enzyme readings, not that B6 supplementation reduces genuinely elevated enzymes:
- In patients with adequate B6 status, supplementation above 3 mg/kg diet has no influence on AST and ALT activities 5
- Studies in hemodialysis patients show that even when vitamin B6 and PLP levels are normal or elevated, AST and ALT remain low due to other metabolic factors unrelated to B6 4
- The AST/ALT ratio, when measured using international standardized methods with PLP addition, does not serve as a reliable index of liver fibrosis or disease severity 3
Food Sources of Vitamin B6 (For Deficiency Prevention Only)
If B6 deficiency is confirmed and contributing to inaccurate enzyme measurements, these foods provide natural sources 1:
- Meat and poultry (particularly important sources) 1
- Fish 1
- Milk and dairy products 1
- Fortified breakfast cereals (key contributors in older adults) 1
- Whole grains 1
- Potatoes 1
The recommended dietary allowance for adults ages 14-70 is 1.3-1.7 mg/day, with requirements reaching 2 mg/day in pregnant women 1
Critical Clinical Pitfalls
Do not use B6 supplementation as a strategy to lower elevated AST/ALT—this approach misunderstands the biochemistry and delays appropriate diagnosis:
- Elevated AST and ALT indicate hepatocellular injury or disease that requires investigation of the underlying cause (viral hepatitis, fatty liver disease, alcohol use, medications, etc.) 1
- B6 deficiency is primarily seen in specific populations: alcoholics, renal dialysis patients, the elderly, post-operative patients, those with infections, and patients on certain medications (isoniazid, penicillamine, anticonvulsants) 1
- In inflammatory conditions or liver disease, plasma PLP levels may be misleading; red blood cell PLP measurements are more reliable 1
When B6 Status Actually Matters for Liver Enzymes
Measure B6 status only when there is clinical suspicion of deficiency causing artificially low enzyme readings:
- Normal plasma PLP values are 5-50 mg/L (20-200 nmol/L) 1
- In conditions with low albumin or altered alkaline phosphatase (common in liver disease), red cell PLP is more accurate than plasma measurements 1
- Vitamin B6 supplementation of 4-6 mg per day is appropriate for confirmed deficiency 1
The appropriate approach to elevated AST/ALT is to investigate and treat the underlying liver pathology, not to manipulate B6 intake. 1