The science of nutrition and healthy eating
The science of nutrition and healthy eating

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The science of nutrition and healthy eating

5 Salt makes food taste good

We have now looked at all of the items that are usually on a food label except salt. Why does salt get a special mention?

There appears to be a link between high salt intake and high blood pressure in some people. If there is too much salt in the diet, the body tends to retain too much water, the volume of blood increases and this raises the blood pressure. High blood pressure is linked with a higher risk of coronary heart disease (CHD) and stroke. As people get older, a small increase in salt intake seems to have a greater effect on blood pressure than it does in younger people. Reducing the salt intake over several weeks can reduce blood pressure.

A small amount of salt is essential for a healthy body but there is plenty in the foods we eat without adding any. Yet we do add salt to lots of our food because we like the taste of it. We have receptors on our tongues that detect salt – alongside the ones that detect sugar – and many people like the taste of salty things. Our taste buds get used to the salty taste. Over time, it is possible to get used to a diet containing less salt. However, the taste buds take time to adjust and for several weeks food without salt will not taste so good.

The advice in the UK is that you should eat no more than 6 g (about 1 teaspoon) of salt each day. However, the average salt intake is around 9 g each day. This may be much higher if you eat a lot of ready-prepared food. To make the amount clearer on food packaging, the ‘traffic-light system’ shows red if there is more than 1.5 g of salt per 100 g of the food, amber for between 0.3 g and 1.5 g and green for less than 0.3 g (Figure 12).

Described image
Figure 12 Nutrition label warning, with a red square, that the food contains more than 1.5 g of salt per 100 g

The chemical name for salt is sodium chloride. You may see ‘sodium’ on some packaging, rather than ‘salt’. You can convert sodium values to salt values by multiplying by 2.5; for example, 0.5 g of sodium is 1.25 g of salt.

Another substance similar to sodium is potassium. Studies have shown that potassium has the opposite effect on blood pressure to sodium: the higher the potassium intake, the lower the blood pressure. In 2013, the World Health Organization issued the first guidelines on potassium intake. Adults should consume more than 4 g of potassium a day. The best sources are fruit, particularly bananas, and vegetables. As you will discover later in the course, there are additional health benefits to increasing fruit and vegetable consumption.

You might like to look at food labels and the range of salt values.

  • What is the highest value you can find in a portion of food?
  • How much of your daily intake would that be?
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