Salt, we’ve been told, is the cause of and solution to hypertension, otherwise known as chronic high blood pressure. Hypertension and its causes can be complicated, so it’s unfortunate that lowering salt intake is the first, and often only, prescription to bring it under control. That medical gospel has been hammered into the public mind for nearly three decades, and this month’s “World Salt Awareness Week” is meant to further reinforce the salt-hypertension dogma. But what if it’s wrong?
The main danger in this relentless anti-sodium campaign is that some of the people who try to reduce sodium but fail will simply give up, not knowing that there are other routes to blood pressure reduction. That’s a problem, considering that eating less salt isn’t as easy as you might think. From the dawn of sodium research, experts have noted the difficulty of getting patients and subjects to adhere to low-salt diets. This is due, at least in part, to a biological drive to consume salt, which is vital to human survival. Without it, the body can’t transmit electrical signals or retain fluids, conditions which lead to malfunction and death. Of course, unlike our ancestors, modern humans live in an environment where salt isn’t scarce.
On average, Americans consume approximately 3,400 mg of salt, or about 1,000 mg more than health agencies like the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), and the Centers for Disease Control (CDC) tell us is the maximum level we ought to consume. Now the regulators are ratcheting up the political pressure: the FDA has announced plans to get food manufacturers to “voluntarily” reduce sodium in their products.
While this might seem like a reasonable approach, the regulators failed to answer two crucial questions:
- Will reducing sodium in foods actually result in lower sodium intake?
- Even if it does, will lower intake result in improved health outcomes?
Unfortunately, the existing body evidence indicates that the answer to both of these questions is likely “no.”
Americans on average get 75 percent or more of their daily sodium from processed and prepared foods, and we have steadily increased the amount of these foods in our diets. While fast food and other prepared meals comprised just 25 percent of the average American diet in 1960, by 2009 processed foods made up approximately 50 percent of our diet. Despite this increased consumption of processed foods, our average level of sodium intake appears to be practically the same as it was in the 1950s. And it’s not just Americans. Data from thousands of people around the world indicates that the natural range of sodium intake—despite differences in culture, income, and race—is remarkably narrow, between 2,600 and 4,800 mg a day.
Still, the FDA and many health authorities insist we would all be healthier if we reduced our intake to less than 2,400 mg a day. Others, like the American Heart Association, set the limit even lower, recommending no more than 1,500 mg of sodium a day.
But even if it’s possible to force consumers to reduce sodium intake to the low levels recommended by health agencies, recent evidence casts doubt on the assumption that less sodium is always better for overall health. For example, recent population studies that tracked sodium intake levels and the subsequent development of disease and death have found that populations at the extreme ends of the sodium spectrum—that is, those consuming more than 7,000 mg or less than 3,000 mg—were more likely to die. The reasons for this correlation are unclear but should cause authorities to question the campaign against the normal range of sodium consumption.
What about all those studies that assert population sodium reduction will lower blood pressure and decrease hypertension-related deaths? Many, like a recent article published in the British Medical Journal, are based on fantasy. The authors based their conclusions on estimates derived from increasingly disputed assumptions that sodium restriction reduces blood pressure and this reduced blood pressure results in decreased health risks. While there is evidence that sodium restriction can reduce blood pressure in some, this is not the case for all or even most people. For example, studies indicate that an estimated 25 percent of people are “salt sensitive” and will experience decreased blood pressure because of moderate sodium restriction. However, the majority of people will have no blood pressure response to decreased salt intake and a small percent might even see their blood pressure rise as a result.
The human population is heterogeneous; no two people are exactly the same. So why would we presuppose a single solution to a problem as complex as hypertension? Sodium restriction might be an effective way to lower blood pressure for some people; but for others, whether because of their physiological makeup or personal preferences, that won’t work. What does work is a more thorough, multi-pronged approach. Losing weight and increasing dietary potassium, for example, are two alternative approaches shown to be as—or in some cases, more—effective at lowering blood pressure than sodium restriction and some combination of these is likely to be the most effective means of improving blood pressure and overall health.
If we really want to help people live longer, it’s time to shelve the one-size-fits-all “salt only” approach to hypertension reduction, and instead inform consumers about the many different ways they might lower their blood pressure so that individuals can find the approach that works best for them.