A new study has uncovered more evidence that widely-circulated advice for cutting the amount of sodium in your diet should be taken with, well, a grain of salt.
The research — undertaken by scientists at the University of California, Davis Department of Nutrition — examined the sodium intake of people in 45 countries over a 50-year period. Interestingly, it seems that consumption levels stayed fairly constant during this time, ranging from 2,600 and 4,800 milligrams per day.
According to the study’s authors, the data shows that people normally self-regulate the amount of sodium they consume within a relatively narrow range, and that increased salt in the food supply hasn’t significantly changed the amount we eat. These results corroborate recent neuroscience research showing that humans and other animals automatically adjust the amount of salt in their diets thanks to specialized networks in the brain.
In May, the Institute of Medicine released a report casting doubt on current federal recommendations regarding sodium, warning that reducing sodium too much could even put some people at risk.
Currently, the U.S. government recommends that people between the ages of 2 and 50 should limit sodium to 2300 milligrams per day, or just under one teaspoon. Meanwhile, people 51 and older — as well as African Americans and people with diabetes, hypertension or chronic kidney disease — should stay under 1500 milligrams, or just a little more than half a teaspoon per day.
In 2010, the American Heart Association (AHA) recommended all Americans cut their sodium to under 1500 milligrams per day. The American Medical Association (AMA) and the AHA defended their low-sodium advice even after the IOM announced its findings this spring.
“Guess what, they’re wrong,” said Judith Stern, professor emeritus of nutrition and internal medicine at UC Davis and one of the study’s authors. “They’re not looking at the latest science. And they’re going along with the general recommendation. My opinion is they shouldn’t do that.”
Stern said it’s not surprising to see resistance among organizations involved in health policy, because a lot of effort has gone into spreading the message about sodium restrictions.
“There’s belief, and there’s science. Belief is very hard to deal with. Science is continually being updated, and that’s what confuses people.”
She said when sodium falls too low, the body reacts to the deficiency by constricting arteries to increase blood pressure. “And that’s a real killer,” Stern said.
She adds that African Americans and people with particular salt sensitivity should still consciously limit their sodium intake. But for most people, she recommends getting a balance of electrolytes like sodium, potassium and other nutrients, instead of focusing on sodium alone.
No Response Yet
Both the AMA and the AHA told Earth Eats that they were not yet ready to comment on the new UC Davis study.
The AHA’s website includes a strong warning about eating too much sodium.
Cardiovascular diseases are the leading cause of death worldwide, and high blood pressure is a major risk factor. For the estimated one in three Americans who will develop high blood pressure, a high-sodium diet may be to blame. In some people, sodium increases blood pressure because it holds excess fluid in the body, creating an added burden on the heart. Too much sodium in the diet may also have other harmful health effects, including increased risk for stroke, heart failure, osteoporosis, stomach cancer and kidney disease. The problem is starting early in America: 97 percent of children and adolescents eat too much salt, putting them at greater risk for cardiovascular diseases as they get older.
The AMA does not have specific guidelines for sodium intake, but its current policy, which rolled out in 2007, calls for a 50 percent reduction in sodium in processed foods, fast food products and restaurant meals over ten years.
- Normal Range of Human Dietary Sodium Intake: A Perspective Based on 24-Hour Urinary Sodium Excretion Worldwide (American Journal of Hypertension)
- Nutrition Policy Rethink – The Body Controls Salt Intake, Restrictions Aren’t Needed (Science 2.0)
- Institute of Medicine, Heart Association Disagree On Sodium (United Press International)
- No Benefit Seen in Sharp Limits on Salt in Diet (New York Times)