When it comes to dunking a piece of sushi in to a tray of soy sauce, most of us don't give it a second thought.

But according to a new study by The George Institute for Global Health, VicHealth and the Heart Foundation, some of your favourite Asian sauces — including soy, oyster and fish — contain far more salt than you might think.

Looking at 150 different sauces, the research showed that a single tablespoon of the average soy sauce contained 61 per cent of our recommended daily salt intake. Alternatively, if you use just one small soy sauce plastic fish packet on a sushi roll, you'll be eating nearly 10 per cent of your daily salt intake.

The research took place over eight years between 2010 and 2018, and showed that of all the Asian-style sauces analysed, fish sauce contained the highest salt content.

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One tablespoon of the popular Asian ingredient contains a whopping 96 per cent of the recommended daily salt intake on average.

"We know that stir-fry dishes are really popular because they are quick, fresh and healthy but too many of us are unaware of just how much salt is hidden in the sauces we use," Heart Foundation Dietitian Sian Armstrong said

"A tablespoon of the saltiest soy sauce contains nearly 90 per cent of your recommended daily salt intake, whereas the lowest salt soy sauce had less than half of that.

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"Too much salt can cause high blood pressure, which increases your risk of stroke, heart and kidney disease. One of the best ways to keep your blood pressure down is by eating less salt so choose a reduced-salt soy sauce when you're cooking a stir-fry and go easy on the sauce."

On average, one tablespoon of soy sauce contains 61 per cent of your recommended maximum daily salt intake.

According to the research, one soy sauce fish packet can contain nearly 10 per cent of your entire day's recommended maximum daily salt intake, while the saltiest soy sauce on supermarket shelves is Chang's Light Soy Sauce, which has more than double the amount of salt as the lowest salt soy sauce, Kikkoman Naturally Brewed Less Salt Soy Sauce.

Oyster sauce has the lowest salt per tablespoon, although on average still has 36 per cent of the recommended daily intake.

"In the past decade we've seen no reduction in the amount of salt in these sauces and there are no targets in place to bring about change," the report's lead author Clare Farrand said in a statement.

"People assume soy sauces can't be made less salty, but this report shows that's not the case, with some soy, tamari and oyster sauces containing much lower salt levels. We want to see all manufacturers reducing the salt levels in their sauces — it can be done."

Earlier this year, a controversial new study found that not having enough salt in your diet may actually be bad for you and suggested campaigns telling people to cut down on salt might only be worth it in countries with very high sodium consumption.

The World Health Organisation recommends capping salt consumption at 5g per day — about a teaspoon — because of the risks associated with increased blood pressure and stroke.

But this target is not known to have been achieved anywhere in the world, note the authors of the study published in The Lancet medical journal.

"We should be far more concerned about targeting communities and countries with high average sodium intake — above 5g (equivalent to 12.5g of salt), such as China — and bringing them down to the moderate range" of 7.5 to 12.5g of salt, said lead author Andre Mente, a professor in the Population Health Research Institute at McMaster University in Canada.

The Heart Foundation recommends a diet high in vegetables, wholegrains, nuts, legumes, healthier oils and a variety of lean proteins including fish, lean meat, poultry and reduced fat dairy.