Too much salt can leave a nasty taste

In our latest Friday science feature Dr Clive Hunt, senior lecturer in nutrition at the University of Huddersfield, guides us through the risks of eating too much salt

Salt is regularly in the news as consumers worry about eating too much from various processed foods, ready-meals and even some bought sandwiches. So what are the facts and how much should we be concerned?

Salt in the diet is nothing new — throughout history it has been prized for its taste and food preservative properties.

Roman soldiers were even paid partly with salt (the origin of our modern word ‘salary’). With the advent of modern refrigeration, the need for salt as a preservative is much less but there are still concerns that we are eating more than is good for us.

Salt (sodium chloride) is needed by the body for many purposes, including proper function of nerve and muscle cells, but the physiological adult requirement is only about 4g per day (equivalent to 1.6g of sodium).

Although there is considerable individual variation, average adult intake in the UK is about 9g per day — hence the concern.

The Government is recommending that we reduce this to 6g because of overwhelming evidence that excessive intake over time can contribute to hypertension (high blood pressure) which, in turn, is a major risk factor for heart attacks and strokes (and can also lead to eye and kidney damage).

So how many people are affected and how do you know if you are one of them?

Some 30 per cent of UK adults have high blood pressure, defined as systolic/diastolic pressure of 140/90 mmHg or more (compared with the ideal of 120/80).

There are around 240,000 deaths (39 per cent of total) each year in the UK from cardiovascular disease (largely heart attacks and strokes in about a 2:1 ratio).

Although primarily affecting the elderly, a significant number are pre-retirement.

A reduction in the population’s salt intake to 6g would save many lives — there is disagreement as to how many, but some scientists estimate 35,000 less deaths and a further 35,000 reduction in non-fatal heart attacks and strokes per year.

So how do we reduce our salt intake?

Obviously we can add less in cooking or at the table, but the main problem is that three-quarters of our intake comes from manufactured foods.

The Food Standards Agency is currently working with food manufacturers and retailers to reduce added salt in a whole range of foods.

In the meantime, we have to be our own guardian. Getting used to looking at labels can help because you can compare the amount of salt per portion with the recommended 6g.

However, sometimes you will see only sodium labelled.

In which case you need to multiply by 21/2 to convert to salt equivalent. The FSA states that more than 1.3g salt per 100g is high, 0.3g or less low and medium in between.

Some foods are obviously salty such as bacon, sausages and crisps.

But much salt is hidden in breakfast cereals, soups, sauces, ready-meals, canned beans and vegetables, smoked meat and fish — even some bread products.

A large study completed in recent years (Dietary Approaches to Stop Hypertension) concluded that a typical diet associated with lowest blood pressure was low in salt but generous in fruit and vegetables (for potassium and fibre) and in low-fat dairy products.

It should also be borne in mind that other major risk factors for high blood pressure are weight, lack of exercise and excessive alcohol, so total lifestyle is important.