molecules Review Broccoli or Sulforaphane: Is It the Source or Dose That Matters? Yoko Yagishita 1, Jed W. Fahey 2,3,4, Albena T. Dinkova-Kostova 3,4,5 and Thomas W. Kensler 1,4,* 1 Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA;
[email protected] 2 Department of Medicine, Division of Clinical Pharmacology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA;
[email protected] 3 Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA 4 Cullman Chemoprotection Center, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA 5 Jacqui Wood Cancer Centre, Division of Cellular Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland DD1 9SY, UK;
[email protected] * Correspondence:
[email protected]; Tel.: +1-206-667-6005 Academic Editor: Gary D. Stoner Received: 24 September 2019; Accepted: 2 October 2019; Published: 6 October 2019 Abstract: There is robust epidemiological evidence for the beneficial effects of broccoli consumption on health, many of them clearly mediated by the isothiocyanate sulforaphane. Present in the plant as its precursor, glucoraphanin, sulforaphane is formed through the actions of myrosinase, a β-thioglucosidase present in either the plant tissue or the mammalian microbiome. Since first isolated from broccoli and demonstrated to have cancer chemoprotective properties in rats in the early 1990s, over 3000 publications have described its efficacy in rodent disease models, underlying mechanisms of action or, to date, over 50 clinical trials examining pharmacokinetics, pharmacodynamics and disease mitigation. This review evaluates the current state of knowledge regarding the relationships between formulation (e.g., plants, sprouts, beverages, supplements), bioavailability and efficacy, and the doses of glucoraphanin and/or sulforaphane that have been used in pre-clinical and clinical studies.