Several anticonvulsants (phenytoin, carbamazepine, valproate) are folate antagonists or accelerate folate metabolism via CYP450 induction. Folate deficiency is one of the best-documented drug-nutrient interactions.
Reynolds (1968) — classic study; Tamura & Stokstad (1976); standard neurology protocol
Megaloblastic anemia, elevated homocysteine, cognitive decline, birth defects if pregnant
L-Methylfolate 800mcg–5mg daily (higher doses for phenytoin users). Do NOT use folic acid — may reduce anticonvulsant efficacy in some patients. Discuss with neurologist.
View on Fullscript: Thorne 5-MTHF (Methylfolate)Discuss with your physician before adjusting supplementation. This is educational content, not medical advice.
Enzyme-inducing anticonvulsants (phenytoin, carbamazepine, phenobarbital) accelerate Vitamin D catabolism via CYP3A4 induction. Deficiency develops faster than with most other drugs.
Valsamis et al. (2006) — significantly lower Vitamin D in long-term anticonvulsant users; increased fracture risk
Bone loss, fractures, osteomalacia, muscle weakness, immune impairment
Vitamin D3 2,000–4,000 IU daily. Monitor 25(OH)D — target 50–80 ng/mL.
View on Fullscript: Thorne Vitamin D/K2 LiquidDiscuss with your physician before adjusting supplementation. This is educational content, not medical advice.
Anticonvulsants impair biotin metabolism. Valproate specifically interferes with biotin utilization and biotinidase activity.
Said et al. (1989) — reduced biotin levels in anticonvulsant users
Hair loss, skin rash, fatigue, cognitive changes
Discuss with your physician before adjusting supplementation. This is educational content, not medical advice.
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