You’re probably eating too much sodium. Here’s what you need to know

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 Australia, it’s estimated that Australians aged two and older eat an average of 2150 milligrams of sodium per day. This is more than the recommended limit of 2000 milligrams.

One in three Australian adults have high blood pressure, which can happen as a result of too much sodium.Credit: Getty Images

But in recent decades, researchers have disagreed about exactly how much sodium is too much, with some suggesting that some local and international government guidelines are too strict. Those reports captured our attention and left many people confused, says 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 says. We asked him and other experts to help set the record straight.

How does sodium affect health?

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,” says 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 7600 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 says. One in three Australian adults have high blood pressure. And researchers say that of all of the problems with our diets, sodium is the most harmful to global health.

How much sodium is too much?

According to Australian guidelines, adults should have no more than 2000 milligrams — less than the equivalent of about 1 teaspoon of table salt — per day, in line with the limits set by the World Health Organisation and International Society of Hypertension.

These guidelines are based on the best available evidence concerning high blood pressure and heart disease, says Dr Frank Hu, a professor of nutrition and epidemiology at the Harvard TH 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 5000 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, says 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 says. 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 adds.

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 2250 and 5250 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.

The sodium debate illustrates many of the challenges of nutrition research, Appel says. Large nutrition trials are much harder to conduct than large drug trials, he says, 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 says.

And, Hu adds, “I don’t think we should wait for perfect evidence to take action.”

So, do I need to cut back on sodium?

If you have high blood pressure, reducing your sodium consumption will most likely help lower it, says Dr Deepak K. Gupta, a cardiologist at Vanderbilt University Medical Centre 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, says 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 says.

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 says.

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 says. 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 says. And those who are prone to low levels of sodium in their blood may not want to adopt a low-sodium diet, she adds.

How will I know if I’m consuming the right amount?

It’s 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 says. Any reduction in sodium should be helpful for most people.

In Australia, about 80 per cent of the sodium people consume comes from processed foods, and 20 per cent comes from salt used at the table or in home cooking, according to Food Standards Australia and New Zealand.

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 says.

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 says.

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 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 2300 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 says 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 adds, and it prioritises many foods that are rich in potassium and don’t contain too much sodium.

The New York Times

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