For centuries, salt has been revered as a flavour-enhancer and food preservative across the globe. Our appetite for salt has not diminished either: many of us add salt during cooking or at the table, and salt has a ubuiquitous presence in pretty much every processed food. Some salt in the diet appears to be important for maintaining balance in the body’s biochemistry. However, as with everything, it is possible to get too much of a good thing. Research suggests that too much salt can push blood pressure up, increasing the risk of circulatory diseases such as heart disease and stroke as it does so. The evidence suggests that health consequences of bagfuls of salt in the diet can be quite unsavoury.
The relatonship between salt and blood pressure has been a topic of hot debate over the past couple of decades. Many studies have been published that suggest that high levels of salt consumption can boost blood pressure. Not surprisingly, the salt industry has also been vociferous in defending its prime commodity. However, despite the protestations of the salt-sellers, a sea of scientific research over the last decade supports the notion that salt can indeed contribute to problems with high blood pressure.
Blood pressure is measured in units known as millimetres of mercury (mmHg), and is expressed as two values, one over the other e.g. 120/70. The upper value refers to the systolic pressure – the maximum pressure that occurs during contraction of the heart. The lower value, or diastolic pressure, is the resting pressure in the system between heartbeats. Heightened blood pressure for a long time has been seen as a major risk factor for heart disease and stroke. A study published recently in the Lancet found that, in individuals aged 40 – 69, an increase in systolic blood pressure of 20 mmHg was associated with a doubling in risk of death due to these conditions.
Studies suggest that broad reductions in salt intake in the population might have important implications for public health. Recently, researchers from the Blood Pressure Unit at St George’s Hospital in London assessed data from 29 trials examining the effect of salt reduction on blood pressure. The data from this mega-trial suggest that if we in the UK halved our salt consumption, we would see meaningful reductions in blood pressure in the population at large. Relieving pressure in the circulation by reducing salt in the diet is expected to tranlate into a 9 and 14 per cent reduction in deaths due to heart disease and stroke respectively in those suffering with high blood pressure. Intererestingly, though, even those classified with normal blood pressure are likely to reduce their risk to some degree too.
Avoiding adding salt or at the table is an obvious way to reduce salt in the diet. However, most of the salt we consume comes from processed food, some of which can be very salty indeed. Savoury snacks, tinned vegetables, cheese and processed meats such as bacom, ham, sausages and beefburgers are obivous sources of salt. However, large amounts of salt can make their way into some unlikely places. For instance, cornflakes, weight for weight, are even saltier than sea water. Cutting back on our intake of processed and pre-packaged foods, and the salt they contain, is one strategy almost certain help preserve our health and well-being in the long term.