Is salt bad for you?

Salt is probably the most common ingredient in our kitchens. Around the world and throughout history, salt has been used to both flavour and preserve food. In the past, salt was highly prized and used sparingly. But in todayâ€™s world it is cheap and ubiquitous. We add it to cooking, use it to season the food on our plate, find it in packaged foods and eat it when dining out, whether at a takeaway or in a restaurant.

Salt is not only important to our food supply but is also used in the manufacture of paper, dyes, soaps and detergents. All this makes salt an important commodity. Worldwide, the major international producers are the United States, China, Germany, India and Canada, where it is produced through both mining and evaporation techniques.

However, many health authorities have expressed concern at the amount of salt we are eating. Potential links between cardiovascular disease and cancer are cited as reasons to cut back on your salt intake. Others have debated this necessity, saying the evidence for harmful effects on health are inconclusive.

While this debate is going on, our salt intake is rising. Though you may not think you eat a lot, and donâ€™t add much to your cooking, salt manages to sneak into your diet from all kinds of sources. So what is salt and where does it come from? How much of it are we eating here in Australia and is that intake a problem?

More than a spice

We use salt to flavour and season foods. Along with sweet, sour, bitter and umami, salt is one of the five basic tastes and there are specific receptors on your tongue that taste it. As well as having its own flavour, salt also draws out and enhances the taste of the foods to which itâ€™s added.

While itâ€™s taken for granted now, salt has a long history of use. Throughout much of history, salt has been so highly prized it has seeped into cultural practices and language. Much of saltâ€™s importance comes from its ability to attract water. By drawing moisture from food, salt helps create an environment that is hostile to most bacteria, which means salt can be used as a food preservative. In the past, this meant people with access to salt could use it to ensure a food supply during times of scarcity. With salt, they could make their summer crops last the winter. Therefore, salt was a valuable commodity that could be traded with other people, thereby bring wealth.

Salt has also been used in religious ceremonies. There are many references to salt in the Bible. Salt is used for ritual purification in the Japanese Shinto religion and itâ€™s been found in ancient Egyptian tombs as one of the offerings made during a funeral. Salt is also surrounded by superstition. When salt is spilled, some people still throw a pinch over their left shoulder to keep the devil away.

Even now we can refer to a person as being â€œsalt of the earthâ€. We talk about â€œtaking something with a pinch of saltâ€. The modern word â€œsalaryâ€ derives from the ancient Roman practice of paying soldiers in salt, while â€œsaladâ€ derives from the Roman habit of salting leafy vegetables. Throughout history, salt has played a pivotal role in families, cultures and nations, but what exactly is it?

Salt chemistry

Salt is made of two primary ingredients. It is a combination of the elements sodium (Na) and chlorine (Cl). While you may think of chlorine as the stuff used to disinfect swimming pools, thankfully in salt it exists in a different form â€” chloride. When sodium and chloride bind together they become salt, the stuff we use in our food. Salt is collected in a number of different ways:

Mining: Most of the salt we eat comes from underground deposits that are mined. These deposits were formed by the evaporation of ancient seas and salt lakes.

Sea salt: Sea water is diverted into shallow basins where the water part is evaporated off, leaving behind salt to be harvested.

Industrial: Water is injected into rock salt deposits, dissolving the salt, which can then be extracted.

Salt in your body

Electrolytes & fluid balance

In your body, salt has a profound effect on physiology. Both sodium and chloride are electrolytes, vital substances that coordinate the subtle and complex balance of fluids in your body.

Your body contains a lot of water. In fact, an average 70kg body contains about 33 litres of water. Itâ€™s vital for life. Water is part of the precisely controlled fluid that bathes every one of the 100 trillion cells in your body. Water is a prime component of your blood. Water fills the cells, tissues and organs of your body. Most importantly, it provides the environment required by the overwhelming majority of your bodyâ€™s biochemical processes. Without water, and plenty of it, your body simply wouldnâ€™t work.

While your cells may need a constant, stable amount of water, throughout the day you are both losing and taking in water. Every time you urinate, have a bowel movement, breathe and sweat, you lose water. On the other hand, every time you eat or drink something, you put water back into your body. So both water loss and water intake are happening.

Itâ€™s electrolytes such as sodium and chloride that keep your cells in a stable environment, despite these daily fluctuations. While you are breathing, sweating, eating and drinking, electrolytes are controlling the movement of water throughout your body and its overall fluid balance. They are making sure your cells remain surrounded by the watery environment they require to function.

Nerve & muscle function

Sodium, chloride and the other electrolytes also play a role in the actions of nerves and muscles. As electrolytes move through cell walls, they activate muscles and neurons. This transfer of electrolytes initiates muscle contraction and relaxation, as well as facilitating the transfer of messages along your nervous system. Without sufficient levels of electrolytes, muscle weakness and irregular muscle spasming can occur.

Is salt bad for you?

In our society, most people consume a lot more sodium than they actually require and there is considerable debate around the health effects of this. Some evidence points to high sodium intake being a problem and, in particular, that it increases your risk of cardiovascular disease and cancer, while others believe this problem has been overstated.

One of the main concerns about salt is its possible association with hypertension, or high blood pressure. Hypertension is a risk factor for cardiovascular disease, as increased blood pressure means your heart is working harder to pump blood around your body. This puts a strain on the heart, increasing the risk of heart attack and stroke.

The connection between a high salt intake and hypertension was first raised in the medical literature over 100 years ago. Ever since then, doctors and scientists have been debating the extent and nature of the link between blood pressure and salt. Some researchers have found salt has a significant effect on blood pressure, while others have concluded its impact is limited, if not negligible.

The method by which salt interacts with blood pressure is also under discussion. Itâ€™s believed that because salt attracts and retains water, it artificially raises the volume of blood circulating around the body. To counteract this, blood vessel walls have to thicken and harden, thereby increasing the pressure in the system. This results in an increased blood pressure reading when you go to the doctor.

The DASH (Dietary Approaches to Hypertension) group has found reducing salt in the diet has a significant impact on blood pressure. In contrast, the prestigious Cochrane group has concluded there is little short- or long-term benefit to reducing salt intake in its two most recent reviews of the issue.

What does seem to be the case is that a certain number of the population are salt-sensitive. In these people, salt will increase blood pressure and it is worthwhile for them people to reduce their intake. The benefit for the rest of the population is debatable and all experts agree the most important intervention for managing blood pressure is reaching and maintaining a healthy weight range.

This advice is not carte blanche for people with normal blood pressure to eat as much salt as they want. Excessive salt intake has been linked to other health problems, including:

Excessive calcium loss from bones, increasing the risk of osteoporosis

Kidney stones

Fluid retention

Some cancers

Again, these health risks are not conclusively linked to salt. However, we eat a lot more salt than we actually need, so itâ€™s worthwhile monitoring and reducing your intake where possible.

Secret salt

While everyone needs salt, you donâ€™t need a lot of it. In Australia and New Zealand, the recommended daily intake for optimum health is 460â€“920mg of sodium per day. These Nutrient Reference Values also recommend people eat no more than 2300mg per day â€” about a teaspoon. In contrast, most people are consuming more than twice that amount.

Most of the sodium we eat doesnâ€™t come from the stuff we add to cooking; it comes from processed foods. In fact, about 75 per cent of our intake is from that one source. In contrast, only 15 per cent of the sodium we ingest is from personal use at the table and in cooking. Most foods, including meat, vegetables and fruit, naturally contain small amounts of sodium, which accounts for the final 10 per cent of sodium intake.

Salt is added to foods that are not obviously salty because itâ€™s a cheap and effective flavour enhancer. Salt is used in the manufacture of bread, breakfast cereals, mayonnaise, cream cheese, some muesli bars and even sweet biscuits. Sodium is also found in many of the flavourings we use in cooking: sauces, salad dressings, tomato ketchup, stock cubes and miso.

Salt summary

Despite the debate, the evidence for salt having a dramatic impact on blood pressure is inconclusive. While it may have a large effect on some salt-sensitive individuals, it seems to have little impact on others. However, most people in countries like Australia and New Zealand do eat far more salt than is actually required, and itâ€™s worthwhile keeping a check on your intake by choosing lower-sodium foods.

Reduce your salt intake

There is a number of ways to reduce your salt intake without compromising on the flavour and enjoyment of food:

Given 75 per cent of most peopleâ€™s sodium intake comes from processed foods, reduce your intake of the foods listed as being high in salt.

Check the labels on the products you buy and try to get foods that contain less than 120mg of sodium per serve.

Eat plenty of fruit, vegetables, salad and wholegrain cereals, as well as smaller amounts of meat and fish and cold-pressed oils.

Retrain your tastebuds by gradually reducing the amount of salt you add to food. Doing this over a period of time gives your palate the opportunity to adjust.

Instead of cooking with salt, add a small amount afterwards. You will get the taste but use less salt. This is because the taste of salt on the surface is stronger than when itâ€™s cooked into the food.

Experiment with herbs and spices or add lemon juice or balsamic vinegar to give flavour to meals without the salt.

Salt varieties

There is a wide range of different salts available, with different colour variations, tastes and mineral content.

Table salt: This is the standard salt available from supermarkets and used in food processing. Itâ€™s made from either mined or industrially extracted salt, which is refined. This refined product is usually mixed with anti-caking agents such as magnesium carbonate to make it free-flowing.

Iodised salt: Concern over the low levels of iodine available in Australian and New Zealand foods has led to some salt being fortified with iodine. Again, this is usually made from mined or industrially extracted salt, which has been refined and mixed with an anti-caking agent.

Rock salt: This is a chunkier, coarser salt that can be added to cooking or ground in a salt mill.

Fleur de sel: This is is a hand-harvested sea salt from the salt pans of France. This region has been producing salt for more than 1500 years and each area produces a salt with a unique flavour. Fleur de sel is often slightly sweet. As they are not refined into pure sodium chloride, sea salts also contain other trace minerals.

Celtic sea salt: Produced in the same regions as Fleur de sel, Celtic is a more coarsely ground, wetter salt. Celtic sea salt is best added to cooking as its texture makes it difficult to sprinkle over food.

Black salt: This is a true rock salt produced in India. While itâ€™s a dark purple colour in the ground, when milled it becomes a grey-pink powder. Its colour comes from the iron, trace minerals and sulphurous compounds in the salt. While it does have a slight sulphurous smell, this dissipates during cooking. Black salt is an excellent accompaniment to Indian food and is also combined with asafoetida, cumin, garam masala and amchur in the Indian spice blend chaat masala.

Maldon sea salt: Derived from Maldon in Essex in the UK, rather than being finely ground or coarse lumps, Maldon salt is thin flakes fragile enough to be crushed over food at the table. Like Fleur de sel, Maldon sea salt has a slightly sweet flavour.

Murray River salt: These pink-coloured salt flakes are produced by pumping underground salt water from deep aquifers to existing salt-affected areas around the Murray Darling basin. Warm temperatures and low humidity allow the salt to crystallise. Murray river salt is similar in texture to Maldon sea salt, meaning itâ€™s ideal to crush over food at the table. Harvesting it helps to desalinate the river.