title: Vitamins, Are They Safe?
abstract: The consumption of a daily multivitamin among people all over the world is dramatically increasing in recent years. Most of the people believe that if vitamins are not effective, at least they are safe. However, the long term health consequences of vitamins consumption are unknown. This study aimed to assess the side effects and possible harmful and detrimental properties of vitamins and to discuss whether vitamins can be used as safe health products or dietary supplements. We performed a MEDLINE/PubMed, EMBASE, Scopus and Google Scholar search and assessed reference lists of the included studies which were published from 1993 through 2015. The studies, with an emphasis on RCTs (randomized controlled clinical trials), were reviewed. As some vitamins such as fat-soluble vitamins (vitamin A, vitamin D, vitamin E), and also some of the water-soluble vitamins like folic acid may cause adverse events and some like vitamin C is widely taken assuming that it has so many benefits and no harm, we included relevant studies with negative or undesired results regarding the effect of these vitamins on health. Our recommendation is that taking high-dose supplements of vitamins A, E, D, C, and folic acid is not always effective for prevention of disease, and it can even be harmful to the health.
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Hamishehkar
authors.affiliation: Iranian Evidence Based Medicine Center of Excellence, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Farhad
authors.initials: F
authors.lastname: Ranjdoost
authors.affiliation: Student Research Committee, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Parina
authors.initials: P
authors.lastname: Asgharian
authors.affiliation: Department of Anesthesiology and Intensive Care, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Ata
authors.initials: A
authors.lastname: Mahmoodpoor
authors.affiliation: Tuberculosis & Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Sarvin
authors.initials: S
authors.lastname: Sanaie
keywords: Adverse effects; Complementary Therapies; Dietary Supplements; Drugs; Safety; Vitamins