Salt myths and facts: Why sodium is essential — and when it becomes a health risk

It would be fair to say that salt has a complicated reputation.

On one hand it’s absolutely essential for life but on the other hand modern diets that are high in sodium intake are linked to high blood pressure and cardiovascular disease.

The real problem is that most people eat far more than their bodies actually need.

Humans love salt because our bodies are biologically wired to crave it.

Sodium, one of salt’s key components, is essential for fluid balance, nerve signalling and muscle function.

When sodium intake drops very low, the human body activates hormones like renin and aldosterone to conserve salt. This highlights that a certain baseline intake is absolutely essential for normal physiology.

Throughout most of human history, salt was scarce and actually prized.

Our ancestors evolved strong taste preferences for it as a survival mechanism.

Today, that ancient drive meets an abundance of salty foods, like a case of combining biology with culture.

Salt also enhances flavour by balancing sweetness, suppressing bitter tastes and making foods more palatable and delicious.

So you can see this dual role of both physiological necessity and sensory delight can explain why salt remains one of the most universally loved tastes across all cuisines and cultures.

This brings me to understanding of how much we are really eating.

Globally the average sodium intake is well above physiological needs and guidelines. The World Health Organisation recommends adults have less than 2g of sodium per day which is about 5 grams or one teaspoon. Many populations consume 3 to 5g of sodium per day or more, mainly from the salt hidden in processed foods, restaurant meals and bread — it’s not all from the salt shaker. For people with hypertension, heart disease or kidney disease the recommended daily intake is around 1.5 to 2g sodium/day.

The evidence to support the claim that too much salt comes with health risks is strong.

A high sodium intake is linked to raising blood pressure and on the other hand, reducing sodium can lower blood pressure across multiple randomised trials.

Heart disease is the leading cause of death in Australia. Elevated blood pressure is a major cause of heart attack and stroke.

Looking deeper at the evidence, there are large cohort studies and meta-analyses generally show that people with higher sodium intakes have a higher risk of cardiovascular disease and stroke than those with lower intakes, with some analyses finding around a 6 per cent increase in cardiovascular risk for each extra gram of sodium.

So is salt really the bad guy? Well salt is not toxic, it is essential to our health and in a healthy diet with minimally processed foods, full of whole real foods, moderately adding salt to your home-cooked meals is unlikely to be harmful for most healthy people.

The problem is an abundance of processed foods in the diet and many takeaway or restaurant foods.

Foods to look out for with hidden sodium include breads, breakfast cereals, ready made sandwiches, processed meats and cheese, frozen meals, canned soups, noodles, salad dressings, tomato-based products, hot dogs, sauces and stocks, packaged nuts, crackers and other savoury snacks.

My recommendation is eat a diet primarily consisting of whole real foods, then you can add your own salt.

Learn to read labels, get your blood pressure checked and if you are wanting to watch your salt intake then embrace seasoning food with herbs and spices.

Salt is not the bad guy but at modern intake levels it does play a clear role in blood pressure and cardiovascular risk.

The key is to focus on less processed foods and a moderate sodium intake, rather than fearing every grain of salt, is where the best evidence points.