Shaking up the Conventional Wisdom on Salt What Science Really Says about Sodium and Hypertension By Michelle Minton January 2017 ISSUE ANALYSIS 2017 NO. 1 CEIAnalysis-minton:Layout 1 1/13/2017 6:09 AM Page 1 Shaking up the Conventional Wisdom on Salt What Science Really Says about Sodium and Hypertension By Michelle Minton Executive Summary • Weigh and thoroughly consider unintended The notion that if you eat too much salt you will have consequences; and high blood pressure has been perceived as medical • Be more effective and less harmful than the gospel that most people—including this author— likely alternatives. believed for the past three decades. But in recent years, research has emerged that challenges this once Based on a review of the scientific literature, the accepted truth. Headlines asking, “Is salt really bad for results of nearly four decades of government efforts your blood pressure?” and declaring, “It’s time to end focused on sodium restriction, and the existence of the war on salt,” have fostered growing suspicion other—possible more effective—means of hypertension among the public that the facts about salt and its reduction as presented in this paper, the current effects on health might not be as clear cut as once government recommendations on sodium fail to meet believed. this standard. Around the world, chronically elevated blood pressure Key findings of this study include the following: affects approximately 40 percent of the adult population. In the United States, nearly one in three • Humans require a certain amount of dietary adults qualifies as hypertensive, which puts individuals sodium in order for our bodies to regulate fluid at greater risk for many serious health events, including homeostasis. Too little sodium will result in the heart attack, heart failure, and stroke. body ceasing to function, while too much can cause strain and death. However, the scientific Considering the cost of the disease, both in terms of community has yet to agree on an optimal human suffering and the burden it places on our health range of sodium intake. care system, government agencies have made reducing • At least in part, the factors that determine what the prevalence of hypertension a top priority. A public amount of salt a person craves (“salt appetite”) health strategy that successfully reduces hypertension may be determined biologically and influence a rates has the potential to improve millions of lives and person’s eating behavior in unconscious ways, save millions of dollars. A misguided approach, on the making it resistant to public policy efforts to other hand, would at best fail to reduce hypertension; lower sodium intake (which may prompt at worst it would encourage behavioral changes that undesirable physiological responses and increase harm, obscure more effective means of risk changes in behavior). reduction, and erode public trust in agencies. • Currently, government health agencies such as For these reasons, population-wide recommendations the U.S. Department of Health and Human should be rare and adhere to rigorous standards. At a Services, U.S. Department of Agriculture, and minimum, such recommendations should: Centers for Disease Control and Prevention recommend adults consume less than 2,300 • Be limited in scope and based on robust, milligrams of sodium per day. This limit high-quality evidence; originated not from a process of scientific Minton: Shaking up the Conventional Wisdom on Salt 1 CEIAnalysis-minton:Layout 1 1/13/2017 6:09 AM Page 2 consultation, but from government fiat, prompted • There is almost universal agreement within the by politicians, bureaucrats, and industry. scientific literature that other dietary factors, • Most human populations consume a relatively such as weight loss and increasing potassium similar level of sodium that is much higher than intake, are as effective as sodium reduction in the U.S. government recommendation, while reducing blood pressure. Such alternative only a handful of populations—some isolated strategies also appear to be beneficial for a tribal and Sub-Saharan peoples—consume less larger portion of the population, have a greater than 2,300 milligrams a day. probability of adherence, and have less chance • Americans have not significantly increased of unintended consequences. sodium intake since such investigations began in the 1950s. This is despite increases in processed Worldwide, government attempts to lower population food consumption, more sodium in processed sodium intake below the recommended limit have failed food, and significant increases in both calorie despite four decades of effort. Considering this failure consumption and average weight. and what we currently know—and do not know—about • Lowering sodium can lower blood pressure for the biological effect of sodium restriction on the some people, but the response may only be seen population at large, government health agencies engaged at a certain extreme consumption level and is in efforts to lower hypertension rates should abandon heterogeneous. When sodium is decreased, their myopic and ultimately futile war on salt. some individuals will experience decreases in blood pressure, some will experience no change, The development of high blood pressure is personal, and some will see their blood pressure increase. multifactorial, not influenced by a single genetic or • Scientific evidence is inconsistent regarding the lifestyle factor; sodium reduction may be advisable for health benefits of moderate sodium restriction some, but ineffective or counterproductive for others. for individuals who are not hypertensive. The most effective approach for risk reduction can only • People do not die as a result of high blood be made on an individual basis by patients and their pressure, but rather from health effects linked to, health care providers. However, if the government is but not necessarily caused by elevated blood going to attempt to lower population hypertension rates, pressure. As a corollary, blood pressure it should refocus its efforts toward helping people lose reduction does not always result in improved weight and increase potassium in their diet with higher a health outcomes. consumption of fruit and vegetables. Compared with • Diets consisting of sodium levels lower than the salt-centric approach, this strategy would have a firmer recommended level are associated with negative grounding in science, be less likely to cause unintended health outcomes, though the cause of this harm, and may even have health benefits in addition to association is unclear. lowering blood pressure. 2 Minton: Shaking up the Conventional Wisdom on Salt CEIAnalysis-minton:Layout 1 1/13/2017 6:09 AM Page 3 Introduction health organizations and their future “Some seek not gold, but there recommendations, and harm the lives not a man who does not public’s health. need salt.” ~Cassiodorus For example, the idea that dietary cholesterol raised blood serum The heterogeneous Health advocates are right to worry cholesterol—and because of that raised about hypertension. It is a serious nature of human heart disease risk—was commonly condition that affects a very large accepted medical wisdom as recently populations percentage of people. Globally, around as last year. Today, it is increasingly 40 percent of the population has makes providing considered erroneous for most of the elevated blood pressure, which increases population, so much so that restrictions universally the risk for strokes and heart attacks.1 on dietary cholesterol were left out of The numbers are even higher among beneficial the most recent government dietary those over 50 years old. In some recommendations.4 This occurred recommendations countries, half or more of the older because of mounting evidence indicating population is hypertensive.2 Public difficult and that, for most people, cholesterol in the health programs to reduce hypertension diet has no effect on serum cholesterol complicated. have the potential to save and improve levels, and may even impart certain countless lives around the globe and nutritional and heart-protective relieve financial pressure on national benefits.5 The link between fat intake health care systems. To achieve this and certain disease risks, once medical goal, policy makers need to identify dogma, has recently been flipped on and implement strategies that actually its head. Though eating a “low fat produce net positive outcomes and diet” had been considered a safe avoid those that prove to be ineffective recommendation to lower cardiovascular or harmful. and obesity risks, much of the modern That is no simple task. The heteroge- research shows variation in the risks neous nature of human populations, with and benefits associated with various innumerable differences in genetics and types of fat. For example, recent studies lifestyle factors, makes providing examining milk fat have found an universally beneficial recommendations inverse relationship, or none at all, difficult and complicated. Thus, between full-fat dairy and diabetes, recommendations made to the general obesity,6 and cardiovascular risk.7 public should be limited in scope and Beginning in the 1950s, health firmly grounded in the most sound and associations began recommending for robust scientific evidence.3 On the people to reduce the amount of animal other hand, health initiatives based fat in their diets.8 That message was on logical leaps and unsubstantiated codified in the U.S. Food and Drug theories erode the public’s trust of Minton: