A recent review of multiple studies indicates that mega-dosing of fat soluble vitamins (A, E, D) and some water soluble vitamins (C, folic acid) may not help prevent disease and can potentially cause harm. Please talk with your doctor or pharmacist about the right combination and dosage of multiple vitamins and other dietary supplements for your health needs. Everyone is unique and different!
– Hamishehkar, Ranjdoost, et al. Vitamins, Are They Safe? Adv Pharm Bull 2016:6(4):467-477.