Salt, like sugar, is one of those divisive nutrients.
The broad consensus is that sugar is an unnecessary, but delicious, evil that harms our health if we have too much (what is too much depends on who you ask) while salt is necessary for survival but also, according to some, the single most harmful substance in food when had in excess.
Again, what is excess depends on who you ask.
In a controversial new book, American cardiovascular research scientist Dr James DiNicolantonio believes we should be eating more salt not less.
He also argues that a lack of salt is driving people to eat more sugar.
Let’s unpack this point first.
DiNicolantonio acknowledges that “all government bodies and health agencies around the world” tell us to cut back on salt.
It is a message that, he believes, may be “predisposing” us to sugar addiction. “The reason? When we become deficient in this essential mineral our body has a built-in safety mechanism [the reward centre in the brain] to make sure that we go out and get more salt so we don’t die from salt deficiency,” DiNicolantonio says.
“The problem is that the other more harmful white crystal, sugar, can hijack this sensitised reward system, potentially making sugar more addictive during states of salt deficiency … Basically the more healthy white crystals we lose from our body [salt] the more cravings we can have for the other more harmful white crystal [sugar].”
Wait, don’t the majority of us eat about five times the recommended amount?
“On the surface it appears everyone is getting to much salt but as I describe in my book The Salt Fix millions of people are at risk of salt deficiency,” DiNicolantonio replies.
He notes that low sodium levels in the blood is “the most common electrolyte abnormality in both the inpatient and outpatient setting”; sleep apnoea, thyroid issues, kidney problems and excess caffeine consumption can cause people to lose more salt; inflammatory bowel diseases and coealic disease affect our ability to absorb salt; exercise and heat cause salt-loss through sweat and those on low-carb diets lose more salt out the urine.
“In other words, there are literally millions of people at risk of salt deficiency and thus sugar addiction,” he says, a topic he also explores in a new editorial.
“The longest living populations in the world population also happen to have the lowest rates of death due to coronary heat disease such as Japan, South Korea, and France all eat a high-salt diet,” DiNicolantonio adds.
Dietitian Dr Joanna McMillan is not convinced by the salt-sugar link, pointing out that “western diets tend to be high in both”, and questions aspects of his argument, but says it raises good questions.
“80 per cent of our average intake of salt in Australia comes from processed foods. It is probable that a high-salt diet is also a high processed food diet and in epidemiological studies it’s hard to tease these factors apart,” McMillan says.
“There has long been a minority but consistent view that we may be overstating the role of salt. It’s certainly not the mainstream view though.”
She adds it is one of “the great nutrition science arguments” that has been debated for more than 20 years.
“The salt research base lacks a key piece of evidence and that’s why there is this debate. The key piece of evidence it lacks is a big definitive outcome trial that randomises people to more versus less salt and looks to see what the effects are on stroke, heart attacks and the like,” says Bruce Neal a senior director at The George Institute for Global Health and Australian chair of the World Action on Salt and Health.
“We’re doing that study at the moment – 21,000 people in China, two and a half years through, another two and a half years to go. It will answer that question.”
In the meantime, he says there is “really strong evidence” that salt is associated with blood pressure and “really strong evidence” that blood pressure is associated with cardiovascular disease.
“What we lack is that direct connection between salt and cardiovascular disease,” Neal says. “Half of the studies will tell you salt is good, the other half will tell you salt is bad. It’s simply not possible to tell.”
But adds that if you asked 1000 experts whether eating more salt would cause harm or benefit, 950 would say “on balance, salt is more likely to be causing harm than benefit”.
The schism of opinion is somewhat united by agreement that if we’re eating a diet that consists primarily of unpackaged, unprocessed whole foods, adding a little sugar or salt here and there is fine.
“The key to health is using real salt to get people to eat real food. I am not saying people can’t use a little bit of sugar as long as this doesn’t lead them to eating an entire bag of cookies,” DiNicolantonio says.
He adds a salt to vegetables, nuts, and seeds on his children’s food.
“Without salt my kids wouldn’t eat healthy,” he says. “This is how salt is meant to be used and the focus on salt being an addictive white substance gives people little options to flavour their food in a healthy way so that they can eat an overall healthy diet. Once people realise that they can use salt to eat real foods and cut back on the sugar then their overall diet and health can improve.”
McMillan says, as with any nutrient, the danger is blaming any one thing.
“Really the answer lies in the fact that a diet with too many highly processed foods [these are the major sources of added sugar, refined carbohydrates, trans fats and salt] is not good for us, while a diet high in minimally processed ‘close-to-nature’ foods is best for us,” she says.
“It comes down to there being an optimal intake [of salt] and this indeed may vary between people. If you’re very active or sweating loads in a hot environment you may well need more salt. Everyone else focus on cutting back on highly processed foods and if you have a whole food diet a pinch of salt on your egg or veggies is probably absolutely fine.”
Neal insists that specific medical conditions aside, “99 per cent of the world’s population” are not at risk of sodium deficiency.
“There’s some truth in some of those things [DiNicolantonio claims],” he says.
“If you just look at one aspect of the evidence you can run off with that conclusion, but the need is for people who can step back and look at the totality of what’s going on – as with most things, the truth is somewhere in the middle. Even then, it’s an imperfect truth.”