Salt and stroke

Most of us don’t think twice about adding salt to our food, but there is now mounting evidence that too much salt can lead to higher blood pressure and increase the risk of stroke. This factsheet explains how much salt really is in our food, the link between salt and stroke and suggests ways of reducing your salt intake.

As a nation we eat far too much salt. According to figures from 1991, we eat an average of 9g a day (one teaspoon contains 5g of salt). Experts now think that figure may have risen by almost a third. COMA (the Committee on the Medical Aspects of Food) has recommended a maximum intake of 7g for men and 5g for women – an average of 6g per day, although our bodies only need 4.1g. Small children and babies need even less salt in their diet.

Salt in food

Most of the salt we consume comes not from salt added during cooking or at the table, but from processed foods. These account for at least two-thirds of our intake of dietary salt. Some foods, such as pickles or smoked meats, are clearly salty. However, many people don’t realise that staples like breakfast cereals, margarine and cheese have a high salt content, as do ready meals, some canned vegetables and snack foods. Bread is the single largest source of salt in our diet. Six average slices of bread contain around 3g of salt – half the recommended daily intake. Salt is used as a preservative and to flavour food, as well as to improve its texture in some cases. It’s also an important part of some food processes – for example, salt helps control yeast growth and the rate of fermentation in bread and inhibits the clouding of vinegar in pickles. Processing can dramatically increase the salt content of foods – for example, pork is low in salt, whereas bacon and sausages are very high. However, both food manufacturers and major supermarkets are now recognizing the importance of reducing salt levels in food and have successfully done so in many products without affecting the taste or causing detrimental effects during processing.

Salt and blood pressure

Salt’s main impact on stroke is through its effect on blood pressure. High blood pressure, or hypertension, is the single biggest risk factor for stroke. It contributes to the hardening of the arteries, making it more likely that they will become blocked by the clots that cause strokes. High blood pressure also puts a strain on the blood vessel walls, increasing the risk of a blood vessel bursting and bleeding into the brain – which is another cause of stroke.

A number of studies have shown that people in Western countries who have a high salt intake are more likely to have high blood pressure, whereas people in less developed countries, which usually eat little or no salt, have few problems with hypertension. Although experts don’t fully understand why a high salt intake leads to raised blood pressure, it’s thought that some people’s kidneys have difficulty dealing with a high salt load. Their bodies respond by pumping more blood read more