Megavitamin therapy is the use of large doses ofvitamins, often many times greater than therecommended dietary allowance (RDA) in the attempt to prevent or treatdiseases. Megavitamin therapy is typically used inalternative medicine by practitioners who call their approachorthomolecular medicine.[1] Vitamins are useful in preventing and treating illnesses specifically associated with dietary vitamin shortfalls, but the conclusions of medical research are that the broad claims of disease treatment by advocates of megavitamin therapy are unsubstantiated by the available evidence.[2][3] It is generally accepted that doses of any vitamin greatly in excess of nutritional requirements will result either in toxicity (vitamins A and D) or in the excess simply being metabolised; thus evidence in favour of vitamin supplementation supports only doses in the normal range.[4][5][6] Critics have described some aspects of orthomolecular medicine asfood faddism or evenquackery.[7][8][9] Research on nutrient supplementation in general suggests that some nutritional supplements might be beneficial, and that others might be harmful;[10][11][12] several specific nutritional therapies are associated with an increased likelihood of the condition they are meant to prevent.[13]
Megavitamin therapy must be distinguished from the usual "vitamin supplementation" approach of traditional multivitamin pills. Megavitamin doses are far higher than the levels of vitamins ordinarily available through western diets. A study of 161,000 individuals (post-menopausal women) provided, in the words of the authors, "convincing evidence that multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease, or total mortality in postmenopausal women".[14]
In the 1930s and 1940s, some scientific and clinical evidence suggested that there might be beneficial uses of vitamins C, E, and niacin in large doses. Beginning in the 1930s inCanada, a megadose vitamin E therapy for cardiovascular and circulatory complaints was developed byEvan Shute and colleagues, named the "Shute protocol".[15] Tentative experiments in the 1930s byClaus W. Jungeblut[16] with larger doses of vitamin C led to Frederick Klenner's development ofmegadose intravenous vitamin C treatments for polio and other viruses in the 1940s.[17] William Kaufman published articles in the 1940s that detailed his treatment of arthritis with frequent, high doses of niacinamide.[18] Rudolf Altschul andAbram Hoffer applied large doses of the immediate release form ofniacin (Vitamin B3) to treathypercholesterolemia.[19][20] In a 1956 publication entitledBiochemical Individuality,Roger J. Williams introduced concepts for individualized megavitamins and nutrients.[21] Megavitamin therapies were also publicly advocated byLinus Pauling in the late 1960s.[22]
Although megavitamin therapies still largely remain outside of the structure ofevidence-based medicine, they are increasingly used by patients, with or without the approval of their treating physicians, often after recommendations by practitioners of orthomolecular andnaturopathic medicine.[23] The proposed efficacy of various megavitamin therapies to reduce cancer risk has been contradicted by results of one clinical trial.[24]
The USRecommended Dietary Allowance forvitamin C for adult women is 76 mg/day and for adult men 90 mg/day. AlthoughLinus 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.[25] Although he claimed and stood firm in his claim that consuming over 1,000 mg is helpful for one’s immune system when fighting a head cold, the results of empirical research do not align with this view. A meta-analysis concluded that supplementary vitamin C significantly lowered serumuric acid, considered a risk factor forgout.[26] One population study reported an inverse correlation between dietary vitamin C and risk of gout.[27] A review of clinical trials in the treatment of colds with small and large doses of Vitamin C has established that there is no evidence that it decreases the incidence ofcommon colds.[28] After 33 years of research, it is still not established whether vitamin C can be used as a treatment for cancer.[29]
The USRecommended Dietary Allowance forvitamin E for adult women and men is 15 mg/day. The US Food and Nutrition Board set atolerable upper intake level (UL) at 1,000 mg (1,500 IU) per day derived from animal models that demonstrated bleeding at high doses.[30] In the US, the popularity for vitamin E as a dietary supplement peaked around 2000, with popular doses of 400, 800 and 1000 IU/day. Declines in usage were attributed to publications of meta-analyses that showed either no benefits or negative consequences from vitamin E supplements.[31][32][33][34][35][36]
The USRecommended Dietary Allowance forniacin for adult women is 14 mg/day and for adult men 16 mg/day. Niacin is available as a prescription product, either immediate release (500 mg tablets; prescribed up to 3,000 mg/day) or extended release (500 and 1,000 mg tablets; prescribed up to 2,000 mg/day). In the US, niacin is also available as adietary supplement at 500 to 1,000 mg/tablet. Niacin has sometimes been used in combination with otherlipid-lowering medications.[37] Systematic reviews found no effect of niacin oncardiovascular disease or death, in spite of raisinghigh-density lipoprotein (HDL) cholesterol. Reported side effects include an increased risk ofdiabetes.[38][39][40]
^Zell M, Grundmann O (2012). "An orthomolecular approach to the prevention and treatment of psychiatric disorders".Adv Mind Body Med.26 (2):14–28.PMID23341413.
^Aaronson S, et al. (2003)."Cancer medicine".Cancer medicine 6 (Frei, Emil; Kufe, Donald W.; Holland, James F., eds). Hamilton, Ont: BC Decker. pp. 76.ISBN978-1-55009-213-4.
^Klenner, Fred R. (1949). "The treatment of poliomyelitis and other virus diseases with vitamin C".Southern Medicine & Surgery.111 (7):209–214.PMID18147027.
^KAUFMAN W (July 1953). "Niacinamide therapy for joint mobility; therapeutic reversal of a common clinical manifestation of the normal aging process".Conn State Med J.17 (7):584–9.PMID13060032.
^Altschul R, Hoffer A, Stephen JD (1955). "Influence of nicotinic acid on serum cholesterol in man".Arch. Biochem. Biophys.54 (2):558–559.doi:10.1016/0003-9861(55)90070-9.PMID14350806.
^Williams, Roger Lawrence (1998).Biochemical Individuality. New York: McGraw-Hill.ISBN978-0-87983-893-5.
^Stone, Irwin (1982).The healing factor: "vitamin C" against disease. New York: Perigee Books.ISBN978-0-399-50764-9.
^Richardson MA, Sanders T,Palmer JL, Greisinger A, Singletary SE (2000). "Complementary/alternative medicine use in a comprehensive cancer center and the implications for oncology".J. Clin. Oncol.18 (13):2505–2514.doi:10.1200/JCO.2000.18.13.2505.PMID10893280.
^Cabanillas F (2010). "Vitamin C and cancer: what can we conclude--1,609 patients and 33 years later?".Puerto Rico Health Sciences Journal.29 (3):215–217.PMID20799507.
^Eidelman RS, Hollar D, Hebert PR, Lamas GA, Hennekens CH (2004). "Randomized trials of vitamin E in the treatment and prevention of cardiovascular disease".Archives of Internal Medicine.164 (14):1552–56.doi:10.1001/archinte.164.14.1552.PMID15277288.
^Curtis AJ, Bullen M, Piccenna L, McNeil JJ (December 2014). "Vitamin E supplementation and mortality in healthy people: a meta-analysis of randomised controlled trials".Cardiovasc Drugs Ther.28 (6):563–73.doi:10.1007/s10557-014-6560-7.PMID25398301.S2CID23820017.
^Miller ER, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E (January 2005). "Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality".Annals of Internal Medicine.142 (1):37–46.doi:10.7326/0003-4819-142-1-200501040-00110.PMID15537682.S2CID35030072.
