In recent years antihypertensive therapy has evolved from treatment for a relatively small number of patients with severe hypertension to treatment for millions of people with mild to severe hypertension. We now treat not only patients at high risk for future cardiovascular morbidity and mortality, of whom nearly all are benefitting from antihypertensive therapy, but also much larger groups of patients each individually at low risk. In this latter group only a small percentage actually benefits from antihypertensive therapy. For example, in the Australian trial in subjects with mild hypertension and no other evidence of cardiovascular disease, only two excess deaths were prevented at the expense of 1000 patient-years of drug treatment (Australian Therapeutic Trial 1980). For most individual members of this group normalizing their mild blood pressure elevation appears to offer no benefit, yet all of them are exposed to antihypertensive therapy and its side effects. When instituting antihypertensive pharmacotherapy in patients with mild hypertension one has to be concerned about these side effects, not just the objective ones (e.g., effects on plasma lipoproteins or glucose which may offset any gains to be obtained by lowering blood pressure), but also subjective ones (e.g., fatigue, impotence) which may markedly affect the quality of life.Nonpharmacologic, in particular nutritional, management of mild hypertension has intuitively major appeal for "lowering blood pressure without side effects." Many studies have evaluated the effects of dietary changes on blood pressure. Several recent symposia have addressed the issue of nutrition and hypertension. Despite this, the report from the first Consensus Development Conference of the Canadian Hypertension Society ("on the management of mild hypertension in Canada") states "Because of conflicting evidence and problems with patient compliance, the conference had difficulty reaching consensus on the effectiveness of salt restriction and, for the obese, of weight reduction in lowering blood pressure" (Logan 1984).This issue of the Canadian Journal of Physiology and Pharmacology contains the proceedings of a workshop "Nutritional Management of Hypertension: Controversies and Frontiers," held in Harrison Hot Springs, British Columbia, September 6–7, 1985. This workshop was organized under the auspices of the Canadian Hypertension Society and made possible by generous financial support from ICI Pharma, Canada (general sponsorship) as well as from the National Institute of Nutrition for the obesity session, and from the Dairy Bureau of Canada for the sodium–calcium session.To define more clearly the controversies and uncertainties, this workshop was organized in a different way than previous meetings dealing with this issue. A clinical scientist working in a particular area was invited to outline the evidence in favour of a given dietary manipulation for the treatment of hypertension, and another one to outline the evidence against. This evaluation would particularly concern evidence regarding "efficacy" and "effectiveness". A discussant then presented an evaluation of the two position papers, followed by a general discussion and a summary by the session chairman. This type of scrutiny of our current knowledge was done for sodium restriction, calcium supplementation, and weight loss. As part of this evaluation two speakers addressed the closely related issues of practical aspects of diet management (e.g. compliance) and the consequences–risks of weight loss in relation to the pathophysiology of obesity.In the last part of the workshop possible future developments in nutrition and hypertension were reviewed, such as "nutrition in the young, early intervention?," vegetarian approach to hypertension, role of dietary fats, and proteins and precursors.The organizing committee very much appreciated that Dr. David Sackett was willing to serve as the scientific chairman of this workshop, to summarize the present "state of the art" on diet modulation in the management of hypertension as well as to propose recommendations for treatment of hypertension in clinical practice and for future research directions.It was a pleasure for me to serve as chairman of the organizing committee. As President of the Canadian Hypertension Society I would like to thank all session chairmen, speakers, discussants, and participants for their enthusiasm and eagerness to explore the topic of nutrition and hypertension. I hope that the scientific information and insight that the proceedings of this workshop offer will convey their commitment.
Do Recommendations for the Management of Hypertension Improve Cardiovascular Outcome? The Canadian Experience