The idea that eating less salt can worsen health outcomes may sound bizarre, but it’s not new. A 1972 paper published in the New England Journal of Medicine reported that the less salt people ate, the higher their levels of renin, a substance secreted by the kidneys, which set off a physiological cascade of events that seemed to end with an increased risk of heart disease. In this scenario: Eat less salt, secrete more renin, get heart disease, and then die prematurely.
Four years ago, Italian researchers began publishing the results from a series of clinical trials, all of which reported that, among patients with heart failure, reducing salt consumption increased the risk of dying prematurely. Other recent studies suggest that reducing sodium to anything like what government policy refers to as a “safe upper limit” (one teaspoon a day if you’re healthy) is likely to do more harm than good. These studies, which covered some 100,000 people in more than 30 countries, showed that salt consumption is remarkably consistent—about one and a half teaspoons a day—among populations over time. This suggests that how much salt we eat is determined by physiological demands, not diet choices. And a handful of these studies—involving type 1 diabetics, type 2 diabetics, healthy Europeans, and patients with chronic heart failure—reported that the people eating salt at the lower limit of normal were more likely to have heart disease than those eating smack in the middle of the normal range. Effectively what the 1972 paper on the salt-renin connection would have predicted.
Proponents of the eat-less-salt campaign tend to deal with this contradictory evidence by implying that anyone raising it is a shill for the food industry (which has been widely criticized for adding salt to processed foods to improve taste) and doesn’t care about saving lives. An NIH administrator told me back in 1998 that to publicly question the science on salt was to play into the hands of the food industry.
When several agencies, including the Department of Agriculture and the Food and Drug Administration, held a hearing last November to discuss how to go about getting Americans to eat less salt (as opposed to whether or not we should eat less salt), these anti-salt proponents argued that the latest reports suggesting damage from lower-salt diets should simply be ignored. According to cardiologist Graham MacGregor, MD, who has been promoting low-salt diets since the 1980s, the studies were no more than “a minor irritation that causes us a bit of aggravation.”
This attitude that studies that go against prevailing beliefs should be ignored on the basis that, well, they go against prevailing beliefs, has been the norm for the anti-salt campaign for decades. Maybe now the prevailing beliefs should be changed.
Next: Who’s right? The other side of the salt shaker.