But the professor cautioned New York City health officials to slow down. He argued that without “convincing scientific evidence of a benefit to eating less salt, much less an assurance of safety, it might be wiser for the New York City Health Department to press for the research that could provide a solid scientific basis for action.”
We respectfully argue that there is in fact a solid scientific basis for action. In 2007, the Treatment of Hypertensive Patients (TOHP) trial reported that a 25 percent reduction in sodium intake in more than 3,000 borderline hypertensive individuals (average blood pressure of 126/85) resulted in a 30 percent decrease in cardiovascular disease and a 20 percent decrease in mortality, both results being statistically significant. Thus we have hard data that reducing salt intake in average individuals means less heart disease and longer life.
Moreover, in 2004, the Institute of Medicine, the scientific organization that sets the nation’s standards for recommended levels of nutrients and is comprised of the country’s leading researchers in health and nutrition, determined that the evidence linking a lower-sodium diet with better cardiovascular health was so strong that dramatic action was required, and required now. They recommended that adult Americans limit their consumption of sodium to 1,200 to 1,500 milligrams a day. That’s about 60% less than what Americans typically consume.
But “big changes,” Professor Alderman argued, “might have unintended harmful consequences.” Let’s pull back a bit. The “big changes” Professor Alderman is concerned about are actually not changes at all; they are a return to what our human bodies are biologically designed to eat. For most of humankind’s existence, salt that was added to food was not a part of our diet. We ate foods that came from the earth, not from factories, and these foods were naturally very low in sodium. An apple has just 3 milligrams of sodium. A russet potato has only about 17 milligrams. The “big changes” we have in fact experienced came about in the 20th century, when America starting consuming foods like Big Macs (a whopping 1,050 milligrams of sodium), Aunt Annie’s Soft Pretzels (1,120 milligrams of sodium), and pepperoni pizza (two slices tally up about 1,250 milligrams of sodium). Going from 3 milligrams of sodium for your afternoon snack to 1,000 and more? That’s big change. That’s why we’re in trouble today, as NYC health officials have correctly pointed out.
Professor Alderman does grant that reducing salt intake seems a reasonable idea, but again urges the NYC health department to wait to apply pressure to food processors. He wants more evidence. He is concerned that policies restricting sodium might backfire, causing health problems.
But how much more evidence do we need? Data coming in right now from Great Britain, where government policies have restricted the amount of sodium the food industry can put in food, have found that the Brits are now eating less sodium overall, and suffering from fewer cardiovascular diseases like hypertension and heart attacks – and living longer. If this is “backfire,” we want it. We need it. Heart disease is the #1 killer of both men and women in the U.S. The number of lives we would save from lowering our salt intake, pointed out my colleague Dr. Stephen Havas at the University of Maryland School of Medicine in 2005, is the equivalent of preventing a jumbo jet from crashing every day.
Professor Alderman concedes that average blood pressure does fall when groups of people reduce their sodium intake by one to two grams, but “there is tremendous variation among individuals,” he points out. Well of course there is. Human reactions vary tremendously to all kinds of medical/nutritional therapy. Some people, for example, lower their blood cholesterol significantly when they cut their intake of saturated and trans fat; others, only modestly. But most do in fact see decreases in blood cholesterol, not increases. The same can be said for sodium intake, as evidenced by the NIH-sponsored DASH (Dietary Approaches To Stop Hypertension) trials over the past two decades. In every DASH study, average blood pressure dropped when sodium intake was curtailed, and the biggest reductions in blood pressure for everyone – people with hypertension as well as those with blood pressure readings as low as 120/80 – occurred in those individuals on the lowest sodium diet, which was 1,500 milligrams of sodium a day.
Finally, Professor Alderman states that “what really matters is whether reducing salt will ultimately prevent heart attacks and strokes and thus improve or extend life.” We agree. We only argue that the time for “whethers” is over. The New York City Department of Health and Mental Hygiene is correct in its desire to act. We have sufficient and strong data showing that reducing salt will in fact saves lives. In Japan and several European countries, many studies have shown that strokes have become less common as sodium intake drops. Deaths from heart attacks have also declined. There is also superb research on populations who never made the “big change” to high-salted, processed foods – populations like the New Guinea Highlanders, Yanomamo Indians, and Eskimos who consume little or no added salt. For their entire life, average blood pressure stays below 120/80. Few in these low-salt-eating cultures suffer hypertension. In the United States, our lifetime risk of developing hypertension is 90 percent. 90 percent.
And just last week, researchers at the University of California, San Francisco, reported in the New England Journal of Medicine that reducing dietary salt could prevent up to 66,000 strokes, 99,000 heart attacks, and 92,000 deaths in the U.S. while saving $24 billion in health costs per year.
We’ll say it one more time: It’s time to act, and kudos to NYC health officials for doing so.
By Robert Vogel, MD
Pritikin Scientific Advisory Board
Author of The Pritikin Edge: 10 Essential Ingredients For a Long and Delicious Life (Simon & Schuster)
Professor of Medicine, University of Maryland
Diet Consultant, National Institutes of Health and National Football League