How much salt is too much? Should I cut back? Photo / Tyler Comrie, The New York Times
Without sodium, you wouldn’t be able to survive. Nerves would fail to fire; muscles wouldn’t contract. But experts say that most people consume far too much of it, increasing their risk of high blood pressure and heart disease.
In the United States, for instance, about 95 per cent of men and 77 per cent of women consume more than 2,300 milligrams per day, a limit federal health officials recommend.
But in recent decades, researchers have disagreed about exactly how much sodium is too much, with some suggesting that federal guidelines are too strict. Those reports captured our attention and left many people confused, said Dr Lawrence Appel, a professor of medicine at the Johns Hopkins University School of Medicine.
But more recent research has clarified some of that murkiness, Appel said. We asked him and other experts to help set the record straight.
Scientific studies from the past 50 years or so have shown a clear pattern: “The more salt we eat, the higher our blood pressure goes,” said Cheryl Anderson, a professor of public health at the University of California, San Diego.
In a 2021 review of 85 clinical trials, for example, scientists looked at what happened to people’s blood pressure when they consumed 400 to 7,600 milligrams of sodium per day. As their consumption increased, the researchers reported, so did their blood pressure. The effect was strongest for people who already had high blood pressure, but the researchers also saw it in people who didn’t.
Managing your blood pressure is one of the most important things you can do to reduce your risk of developing heart disease or having a stroke, Anderson said. Nearly half of adults in the United States have high blood pressure. And researchers say that of all of the problems with our diets, sodium is the most harmful to global health: Excessive salt consumption causes close to 2 million deaths each year, they estimate, mainly from cardiovascular disease.
According to the US dietary guidelines, adults should have no more than 2,300 milligrams — equivalent to about 1 teaspoon of table salt — per day. The World Health Organisation and International Society of Hypertension have a slightly lower limit at no more than 2,000 milligrams per day. And the American Heart Association says that while no more than 2,300 milligrams per day is a good target to aim for, it’s even better to avoid going over 1,500 milligrams per day, especially if you already have high blood pressure.
These guidelines are based on the best available evidence concerning high blood pressure and heart disease, said Dr Frank Hu, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health.
But not all experts agree. In several studies published in the past decade or so, for instance, researchers reported that it was only people who consumed much more sodium — on the order of 5,000 milligrams per day — who had a greater risk of heart disease or earlier death. Those findings suggested that the sodium guidelines set by health organisations across the world were too strict, said Dr Martin O’Donnell, a professor of neurovascular medicine at the University of Galway in Ireland.
This perspective garnered a lot of mainstream attention, Appel said. But other researchers found serious flaws with the contradictory studies; the main issue being that they could not accurately measure how much sodium people consumed, he added.
In a 2022 analysis, Hu and his colleagues compiled the results from studies that used more rigorous methods. Among 10,700 adults who were followed for nearly nine years, most consumed between about 2,250 and 5,250 milligrams per day. The researchers found that those who consumed the least amount of sodium had the lowest risk of cardiovascular disease. And as sodium consumption increased, so did cardiovascular risk, a finding that supports the US guidelines.
The sodium debate illustrates many of the challenges of nutrition research, Appel said. Large nutrition trials are much harder to conduct than large drug trials, he said, especially when looking at long-term health risks like heart attacks and strokes. Instead, nutrition researchers often rely on study designs that can only show associations between certain eating patterns and health, and conflicting results are common.
But the evidence to support reducing sodium consumption to the recommended levels is “pretty darn strong,” Appel said.
And, Hu added, “I don’t think we should wait for perfect evidence to take action.”
If you have high blood pressure, reducing your sodium consumption will most likely help lower it, said Dr Deepak K. Gupta, a cardiologist at Vanderbilt University Medical Center in Nashville, Tennessee. This has been shown in many studies, including a 2023 trial led by Gupta, which suggested that, in most people, low-sodium diets reduced blood pressure about as well as a medication did.
But you shouldn’t wait until you have high blood pressure to think about sodium, said Alta Schutte, a professor of cardiovascular medicine at the George Institute for Global Health in Australia. Excess sodium throughout life can gradually damage blood vessels and eventually lead to high blood pressure. “It’s a cumulative effect,” she said.
Several recent trials have shown that adults with normal blood pressure who cut back on sodium were less likely to develop high blood pressure than those who didn’t reduce their consumption. “Prevention is certainly much better than treatment,” Hu said.
At the same time, these and other studies have shown that getting enough potassium may be just as important as cutting back on sodium, Schutte said. Getting adequate potassium from your diet can reduce your risk of high blood pressure and heart disease, in part because potassium helps your kidneys remove extra sodium from your blood.
But some people should avoid consuming too much potassium. If you have kidney disease or are taking certain medications like potassium-sparing diuretics, check with your doctor before increasing your consumption, Schutte said. And those who are prone to low levels of sodium in their blood may not want to adopt a low-sodium diet, she added.
The average adult in the United States consumes about 3,500 milligrams of sodium per day. And it can be challenging to cut back to 2,300 milligrams without making drastic dietary changes. It’s also difficult to know if you’re over the limit in the first place, since no simple test can measure this. But it’s not all or nothing, Hu said. Any reduction in sodium should be helpful for most people.
In the United States, about 70 per cent of the sodium people consume comes from processed foods and dining out, according to the Food and Drug Administration. The best way to reduce your sodium consumption is to eat less of these foods and to cook more of your meals at home, Appel said.
Vegetables, fruits, beans, nuts and dairy products are all rich sources of potassium, and eating more of these foods can boost your potassium while also probably reducing your sodium, Hu said.
You can experiment with adding flavour to your food by using more herbs and spices and less salt. Research suggests that spicy seasonings like chilli peppers and acids like lemon juice and vinegar can enhance the taste of salt, making a little bit go a longer way. And in taste tests of store-bought tomato soup, people said that a low-sodium version seasoned with garlic, celery, oregano, bay leaves and black pepper was just as tasty as a full-sodium version.
When buying packaged foods, Anderson said that a good rule of thumb was to choose products with no more milligrams of sodium per serving than calories. This will help you stay below the 2,300 milligram daily limit. And be aware that certain canned foods, like beans and vegetables, are often high in sodium; draining and rinsing them can reduce the load.
Keep in mind, O’Donnell said, that your overall eating pattern is more important than any one ingredient. The Mediterranean diet has been shown to reduce your risk of cardiovascular disease, he added, and it prioritizes many foods that are rich in potassium and don’t contain too much sodium.
This article originally appeared in The New York Times.
Written by: Alice Callahan
Photographs by: Tyler Comrie
©2024 THE NEW YORK TIMES
Diet fads may come and go, but no-joke rules about our heart health are clear to experts.