Update with Dr Alan Barclay

Reducing your risk of heart attack and stroke by balancing sodium and potassium.
Dietary guidelines from around the world recommend that people eat less, or limit, added salt and salty foods. They are talking about sodium chloride, the most common salt added to foods, which has been consumed by humans for many thousands of years. As well as enhancing flavour, salt has other important roles in food including acting as a preservative and affecting a food’s texture.

It’s the sodium in salt that’s thought to be a health problem when consumed in excessive amounts. Salt is approximately 40% sodium and 60% chloride. The World Health Organisation (WHO) currently recommends that adults consume less than 2 grams (2000mg) of sodium, which is equivalent to less than 5.1 grams of added salt, each day. Population surveys from around the world indicate that most people eat more salt than is required for good health. The most recent Australian Health Survey, for example, indicates that the average Australian adult consumes over 2.4 grams (2430mg) of sodium each day, equivalent to over 6.2grams of salt. This sodium is what occurs naturally in food and is added during food processing and does not include what is added during food preparation at home or at the table, so for most of us it’s likely to be an underestimation.

Hence the general advice to people to eat less salt. The main reason why we need to eat less salt is that habitual consumption of large amounts raises many people’s (but not everyone’s) blood pressure, and in turn may increase the risk of heart disease and stroke. High salt intakes are also associated with an increased risk of developing stomach cancer. While advice to reduce the amount of sodium in the diet makes good sense, it is important to remember that we do not need to completely avoid all sodium. Indeed, like most nutrients too little sodium may not be good for our health. Indeed, a recent large study of adults living in 17 countries found that both lower (less than 3g) and higher (more than 6g) sodium intakes were associated with an increased risk of major cardiovascular events like heart attack and stroke, and that intakes in the middle were associated with the least risk. We probably shouldn’t be surprised, this phenomena – characterised by a U or J – shaped curve – is quite common in nutrition: too little of a particular nutrient really can be just as detrimental to health as too much.

Another emerging piece of the proverbial puzzle is that the ratio of sodium to potassium in the diet also matters. Relatively higher intakes of potassium are associated with lower blood pressure, and lower risk of major cardiovascular events. Excellent sources of potassium include fruits, vegetables, wholegrains, seafood, and yoghurt – foods that most of us should be eating more of. The WHO recommends that the sodium : potassium ratio be no more than 1 : 1, or in other words, you should aim to consume no more sodium than potassium.

In most parts of the developed world, sodium is added to food during food processing, and consequently processed foods are usually the primary source of sodium in foods – not salt added to foods during food preparation at home or at the table. It is therefore important that we encourage food manufacturers and processors to add less salt to foods to help us to reduce our sodium intake. The GI Symbol Program has category-based Nutrient Criteria that include limits for sodium to encourage manufacturers to reduce the amount of sodium that they add to foods.

To help readers of GI News reduce their sodium intakes and increase their potassium intakes, we will include sodium : potassium ratios in the recipes we publish.

GI Symbol Program
Dr Alan W Barclay PhD,
Chief Scientific Officer,
Glycemic Index Foundation (Ltd):
alan.barclay@gisymbol.com
www.gisymbol.com

GI testing
Fiona Atkinson,
Research Manager,
Sydney University Glycemic Index Research Service:
sugirs.manager@sydney.edu.au
 
GI database
www.glycemicindex.com