Megavitamin therapy is the use of large doses of vitamins, often many times greater than the recommended dietary allowance (RDA) in the attempt to prevent or treat diseases.
[18] Rudolf Altschul and Abram Hoffer applied large doses of the immediate release form of niacin (Vitamin B3) to treat hypercholesterolemia.
[23] The proposed efficacy of various megavitamin therapies to reduce cancer risk has been contradicted by results of one clinical trial.
Although Linus Pauling was known for highly respectable research in chemistry and biochemistry, he was also known for promoting the consumption of vitamin C in large doses.
A meta-analysis concluded that supplementary vitamin C significantly lowered serum uric acid, considered a risk factor for gout.
The US Food and Nutrition Board set a tolerable upper intake level (UL) at 1,000 mg (1,500 IU) per day derived from animal models that demonstrated bleeding at high doses.
[37] Systematic reviews found no effect of niacin on cardiovascular disease or death, in spite of raising high-density lipoprotein (HDL) cholesterol.