Sodium

What is salt?

Salt is a mineral made mostly of sodium chloride. It has been used to flavour and preserve food for centuries, but recently attention has focused on the health risks of high-salt diets, specifically due to the sodium in salt.

You need sodium for your body to function, but too much is linked to high blood pressure, which can lead to heart disease, stroke and chronic kidney disease. Most Australians are consuming more salt (and therefore sodium) than is recommended — nearly twice as much on average.

What’s the difference between salt and sodium?

Sodium chloride — the compound in salt — combines the elements sodium and chlorine. Salt is 40% sodium and 60% chlorine by weight. It’s the sodium that can be damaging to your health.

Salt is usually measured in grams (g) and sodium in milligrams (mg).

How much sodium do I need each day?

It is recommended that adults have no more than 2,000 milligrams of sodium each day, which is equivalent to about 5 grams of salt or 1 teaspoon. This is the amount that may help prevent chronic disease, such as high blood pressure. An adequate amount of sodium per day for adults is 460mg to 920mg (equivalent to 1.15 to 2.3g of salt per day).

Recommended sodium intake for Australian children

What are the risks of too much sodium in your diet?

Your body needs sodium to regulate blood pressure, balance fluids in the body and for nerves and muscles to function properly.

Too much sodium in the diet, however, can lead to health risks such as:

• high blood pressure
• chronic kidney disease
• heart disease and heart attack
• stroke

Can you have too little or too much sodium in your body?

Sodium is needed by your body to regulate body fluids. Sodium comes into your body from food and drink and is lost in sweat and urine. Generally, a healthy diet will easily provide enough sodium for the body to function without any problems.

In some circumstances, sodium levels can become unbalanced. Your sodium levels are measured in millimoles per litre (mmol/L), with a blood test.

• Hyponatraemia is too little sodium in the blood (below 135 millimoles per litre for an adult).
• Hypernatraemia is too much sodium in the blood (more than 145 mmol/litre for an adult).

Hyponatraemia

Hyponatraemia is rarely caused by too little sodium in the diet. Mostly, it is caused by too much sodium being lost from the body — for example, by diarrhoea, vomiting, excessive sweating (hyperhidrosis) or as a side effect of some medicines — or by excess fluids in the body (such as by overconsumption of water or kidney disease).

Hyponatraemia can happen regardless of a person’s state of hydration. Put simply, there is just too little sodium for the amount of fluid in the body.

Symptoms of hyponatraemia may include confusion, forgetfulness, lack of energy and cramps. Nausea, vomiting, headache, muscle twitching and seizures may be signs of severe hyponatraemia, which can lead to coma or death.

Hypernatraemia

Hypernatraemia is usually due to excessive loss of water — known as dehydration — usually combined with not replacing the water. The water can be lost through vomiting, diarrhoea, excessive sweating, not drinking enough or taking certain medicines. The result is too little water for the amount of sodium in the body.

Symptoms of hypernatraemia include thirst, tiredness, headache, nausea and loss of appetite. When severe, symptoms may include confusion, irritability or seizures, and it may lead to death.

Do you need more sodium if you’re exercising strenuously or in the heat?

Sodium is one of the body’s electrolytes — minerals that can carry an electric charge when dissolved in fluids, such as your blood. Electrolytes are involved in many processes in the body, including regulating body fluids.

When someone loses a substantial amount of fluid (sweating), which can be caused by prolonged strenuous exercise or when doing prolonged physical work in the heat, they will also lose more electrolytes — mainly sodium. To make up for the loss of sodium, some people — for example, some endurance athletes — may need to consume more sodium than the guidelines suggest.

What foods and medicines are high in salt?

The majority of salt consumed in the Australian diet comes from processed and packaged foods, not from salt added at the table or during cooking. Food does not have to taste salty to have a high-salt content. For example, sweet biscuits can be high in sodium because of the sodium bicarbonate (baking powder) in them — not from added salt.

These foods are typically high in sodium:

• packaged and processed ‘ready meals’
• potato crisps and salty snack foods
• processed meats and meat products, such as ham, sausages, bacon, meat pies, sausage rolls and chicken nuggets
• burgers and pizza
• cheese
• yeast spread (such as Vegemite)
• certain sauces, spreads and condiments, such as soy or fish sauce

Effervescent, soluble pain-relief medicines and vitamin supplements — those that fizz when you dissolve them in water — may contain high levels of sodium. Check the packet or Consumer Medicines Information leaflet for the sodium content if you take these regularly. Some of these soluble pain-relief medicines may contain more than 400mg of sodium per tablet.

How can I find out how much sodium is in food?

Food labels in Australia must list total sodium content. This includes naturally occurring sodium, sodium from food additives and sodium from added salt. They all count towards your daily sodium allowance. The labels must also record all salt and sodium-containing additives in the ingredients list.

See the nutrition information panel on the packaging for the:

• total amount of sodium you are consuming in the ‘per serve’ column
• amount of sodium ‘per 100g’, which helps you compare the sodium content of similar foods

Australian nutrition experts recommend foods with less than 400mg sodium per 100g; less than 120mg per 100g is better. Foods labelled ‘low salt’ have less than 120mg sodium per 100g.

These ingredients may indicate high sodium: baking powder, celery salt, garlic salt, onion salt, meat or yeast extract, MSG (monosodium glutamate), rock salt, sea salt, sodium bicarbonate, sodium nitrate, vegetable salt and stock cubes. Sodium from any source, not just salt, may carry health risks if overconsumed.

How do I convert sodium to salt?

You can convert the amount of sodium in a food into its equivalent weight in salt (sodium chloride). To convert milligrams (mg) of sodium into grams (g) of salt, multiply the amount of sodium by 2.5 and divide by 1,000.

For example, 100mg of sodium × 2.5 = 250mg salt divided by 1,000 = 0.25g salt. So, 100mg sodium equates to 0.25g of salt.

Are some types of salt healthier than others?

In addition to plain table salt, there is sea salt, pink salt, Himalayan salt, Celtic salt, black salt and more. Some brands claim to offer health benefits because some salts contain additional minerals — or because of certain processing methods. However, these minerals may only be present in trace amounts and you’re likely to get them from other sources in your diet.

Regardless of these claims, all salt contains sodium, which if overconsumed can cause health problems.

Iodised salt is salt that’s been fortified with iodine, a mineral essential for health — especially for pregnant and breastfeeding women — as well as women planning to get pregnant. Iodine is needed to make thyroid hormones, and iodine deficiency can cause brain damage and mental impairment.

Table salt with iodine is widely available, and all Australian commercial bread (except organic bread) is made with iodised salt.

How can I reduce my sodium intake?

More than three-quarters of salt consumed in the Australian diet is from salt added to processed foods. Avoiding these foods or choosing more wisely can substantially reduce your sodium intake.

It’s also possible to ‘retrain’ your taste buds to adapt to having less salt. Reduce your salt intake gradually and after a while, you might not notice the lack of salt.

Changing your diet can reduce your sodium intake substantially:

• Follow the Australian Dietary Guidelines and eat fresh and unprocessed foods, including plenty of vegetables, fruits and whole grains.
• Check food labels and choose lower-sodium foods.
• Choose foods labelled as ‘low-salt’, ‘salt-reduced’ or ‘no added salt’.
• Avoid adding salt at the table or while cooking.
• Use garlic, herbs, spices, lemon juice and vinegars to flavour food.
• Cook your own food — while eating less takeaway food and pre-packaged foods.
• Avoid cured and salted processed meats.
• Limit salty snacks.

Are salt substitutes safe?

Salt substitutes and reduced-sodium salts may not be suitable for everyone.

These products usually combine sodium chloride with potassium chloride, another mineral. This can substantially reduce the amount of sodium in the product. But salt added at the table and in cooking contributes only one-fifth of Australians’ sodium intake — most of it is from processed foods.

People who have kidney problems or who take non-steroidal anti-inflammatory medicines, certain blood pressure medications, including ACE inhibitors, angiotensin II receptor blockers, and some diuretics, should seek medical advice before taking salt substitutes. They can lead to a life-threatening build up of potassium.