Sodium and Salt

Summary

Sodium is a mineral. It’s there naturally in water, rocks, soils, and also in plants and animal bodies. Salt is a mixture of sodium and chlorine. We get 90% of our sodium by adding salt when we cook at home or from eating processed foods like snacks, bread, and cereals.

A tiny amount of sodium is vital for good health. It keeps our nerves and muscles working and balances our blood pressure. A child can get the recommended daily amount from one or two pinches of salt; an adult only needs about a teaspoon. Most New Zealanders are eating too much salt. It mostly (75%) comes from processed foods.

Over time, too much sodium can put a strain on someone’s heart, and maybe even cause a heart attack. Too much is also not good for our kidneys and bones. We can aim to eat less salt to keep sodium levels down.

What is it?

Sodium (Na) is a mineral element. It’s naturally present in seawater, spring waters, mineral deposits and the bodies of animals and plants. We get most of our sodium as salt: there is about 390 milligrams of sodium in every gram of salt we eat.

What’s the difference between salt and sodium?

They’re often confused, but not the same thing: the mineral sodium is one element of the compound we call salt. The ANZ Food Standards Code defines salt as “

What foods do we get sodium from?

About 10% the sodium we consume is already there naturally. Plants are generally low in sodium, but some like silverbeet and soybeans have higher levels relative to others. We add another 15% by using salt in cooking and to prepare foods. But a massive 75 % of our sodium comes to us in the processed foods we eat and drink: in everything from bread, cereals and cheese to pizzas, pretzels and pastries.

Why do we need sodium?

We need some – but not very much – sodium in our bodies to help manage our blood pressure and the volume and acidity of our body fluids. It’s also needed for normal nerve and muscle functioning. This is because sodium is one our major electrolytes (substances that can carry an electric charge when they are dissolved in a liquid like blood).

How much do we need?

The NZ Nutrition Foundation reckons adults need between 920 and 2300 mg of sodium each day from all sources: that’s less than a third to about a teaspoon of salt. The World Health Organization (WHO) recommends aiming at no more than 2000 mg sodium (5 g salt) a day. For children aged 9 to 13 years, the NZ Ministry of Health recommends 400 to 800 mg sodium/day and no more than 2000 mg/day. A pinch of salt contains about 400 mg sodium.

Why is too much sodium a problem?

Too much sodium attracts water, which increases the volume of blood in our bodies. This means our heart has to work harder pushing more blood around the body. Over time this can put a strain on our heart and blood vessels, raise blood pressure and lead to strokes and heart attacks. Too much sodium can also cause kidney disease, osteoporosis (weakening of the bones) and other health conditions. The average New Zealander consumes more sodium than recommended ­– around 3500 mg/day (which is about 1.5 to 1.75 teaspoons salt). A bit too much for a short while won’t hurt you– but it’s a good idea to aim low for the long term.

Why is there so much sodium in processed foods?

Sodium is not just in salt. It’s in other ingredients too: like baking soda (sodium bicarbonate); salty monosodium glutamate (MSG); preservatives like sodium nitrite and sodium sulphite; stabilisers like sodium alginate; and antioxidants like sodium ascorbate. A food doesn’t have to taste salty to contain sodium: there’s sodium in breads, yoghurts, sauces, cereals and biscuits and it all adds up. The Nutrition information panel (NIP) on NZ packaging lists sodium values, but in other countries, like the UK, it may list salt values.

What does low, medium and high sodium/salt mean in NZ?
Low sodium or salt foods are defined by our Food Standards Code as containing less than 120 mg of sodium per 100 g of food. Health experts agree with this and also add:
Medium salt foods with between 120 and 600 mg of sodium (0.3 to 1.5 g salt) per 100 g.
High salt foods with more than 600 mg of sodium (1.5 g salt) per 100 g. 
Check the NIP panel on food packs to see how much sodium they contain as it can vary a lot between brands. Aim for fresh, lower sodium foods in general and these per 100 g sodium values for processed items: breads < 450 mg; cereals or spreads <400 mg; crackers <350 mg.

Funky fact

There’s more sodium (1100 mg) in a large white scone than in an average takeaway serve of fish and chips consisting of two fillets of fish and a scoop of chips (1021 mg).

Now you have read the Fact Sheet give Harold's Quiz a try!

References

Foodwatch, 6 August 2010. “How to Convert Sodium to Salt (and Salt to Sodium)”: author Catherine Saxelby. Retrieved from: http://foodwatch.com.au/blog/measures-and-conversions/item/how-to-convert-sodium-to-salt-and-salt-to-sodium.html 10 August 2017.
Ministry of Health, July 2012. “Food and Nutrition Guidelines for Healthy Children and Young People (Aged 2–18 years): a Background Paper. Partial Revision February 2015.” Retrieved from: http://www.health.govt.nz/system/files/documents/publications/food-nutrition-guidelines-healthy-children-young-people-background-paper-feb15-v2.pdf 10 August 2017.
New Zealand Nutrition Foundation, April 2013. “Sodium”.  Retrieved from: https://www.nutritionfoundation.org.nz/nutrition-facts/minerals/sodium 9 August2017.
Stroke Foundation, NZ, n.d. “Slash the Salt”. Retrieved from: http://www.stroke.org.nz/resources/slash-the-salt.pdf 9 August 2017.
US Food and Drug Administration (FDA), 2 June 2016. “Sodium in Your Diet”. Retrieved from: https://www.fda.gov/food/ingredientspackaginglabeling/labelingnutrition/ucm315393.htm 9 August 2017.
World Action on Salt & Health (WASH), n.d. “Salt and Health Factsheets”. Retrieved from: http://www.worldactiononsalt.com/salthealth/factsheets/index.html  9 August 2017.

Useful links

Saltwise Quiz. Retrieved from: http://www.saltwise.co.nz/ 9 August 2017.

Life Education Trust factsheet The Highs and Lows of Sodium: It All Adds Up.