Dr. Bernhard Juurlink recently presented this talk on broccoli sprouts to the 2017 Convention of the International Sprouts Growers Association. Dr. Juurlink is also a volunteer Board member of the Canadian Neurovascular Health Society.

Hippocrates Was Right
Bernhard H.J. Juurlink
Professor emeritus,
Department of Anatomy & Cell Biology
College of Medicine,
University of Saskatchewan

Mitochondrial dysfunction, oxidative stress and associated inflammation underlie aging and associated chronic diseases. Nrf2 activators set in motion a signaling pathway that that alters gene expression that ultimately decreases oxidative stress and associated inflammation and as well improves mitochondrial function. This pathway was slowly unraveled following the pioneering research by Dr. Lee W. Wattenberg and later Dr. Paul Talalay to understand why certain foods were associated with a decreased risk of developing cancer. It was quickly discovered that what these foods had in common were phytochemicals that caused increased activities of phase 2 enzymes, enzymes involved in the metabolism of drugs and xenobiotics, including carcinogens. Eventually these cancer-preventing phytochemicals were discovered to activate the Nrf2 signaling system that results in the alteration of expression of dozens of genes. Such phytochemicals are now called Nrf2 activators and one of the first of such dietary phytochemicals identified by Dr. Talalay’s group was sulforaphane, an isothiocyanate metabolite of sulforaphane glucosinolate (glucoraphanin). This research group also identified that broccoli sprouts of particular cultivars are a rich source of sulforaphane glucosinolate.

Although the initial focus of research attention was the ability of Nrf2 activators to decrease the probability of cancer formation and progression, I noted that the increased expression of phase 2 enzymes should also decrease oxidative stress and associated inflammation, areas of my research interest. I published an hypothesis paper on this idea in 2001. I, and my colleagues, subsequently obtained funding from the Saskatchewan Agricultural Development Fund to test this idea. My laboratory has shown that intake of Nrf2 activators (including sulforaphane whether via broccoli sprouts consumption or sulforaphane administered by gavage) will decrease oxidative stress and associated inflammation in rodent models of aging. Positive outcomes from these experiments include decreased blood pressure, better brain aging, better locomotory function during old age and better renal function. We also have shown that stroke-prone hypertensive rats on a diet that contained high sulforaphane broccoli sprouts had offspring with better blood pressure and less oxidative stress and inflammation in every tissue examined. That is, a dietary Nrf2 activator had positive effects on fetal determinants of adult health. This latter, at least in part, was associated with normalizing the epigenome of the kidneys.

Subsequently, other laboratories have shown that intake of Nrf2 activators have positive effects on a variety of diseases that have dyslipidemia, oxidative stress and inflammation as underlying disorders in various animal models. Of great significance is that a number of clinical trials have shown that consumption of high sulforaphane broccoli sprouts or extracts thereof have therapeutic effects in humans. These include trials showing positive effects on decreasing helicobacter infections, normalizing lipid metabolism, normalizing glucose control in type 2 diabetes, promoting the ability to detoxify airborne carcinogens, and ameliorating the symptoms of autism and possibly schizophrenia.

Hippocrates stated that food should be our medicine and medicine our food. We are at a stage where Hippocrates dictum can be put into practice. Broccoli is not the only vegetable variety that contains sulforaphane glucosinolate. Black Tuscany kale has even a better glucosinolate profile than the Calabrese broccoli cultivar my laboratory has used. However, a word of caution: although sulforaphane glucosinolate and certain other glucosinolates activate the Nrf2 signalling pathway, a number of glucosinolates are goitrogenic. It becomes very important to know the glucosinolate profile of the sprouts before promoting their consumption. I am not sure if the sprouts of all the broccoli seeds labelled Calabrese have the same glucosinolate profile as the ones we used. A very useful service the International Sprout Growers Association can provide their membership is to determine the glucosinolate profiles of the Brassica sprouts grown from seeds being sold by the membership.

Acknowledgments: I thank my colleagues and the funding agencies that supported my research. I have been very fortunate in having wonderful undergraduate students, graduate students, post- doctoral fellows and other colleagues participating in the research in which I have engaged.