Saturday, April 19, 2003
M A I N   F E A T U R E


Beware, salt attack!
John Briffa

FOR centuries, salt has been revered as a flavour enhancer and food preservative. Our appetite for salt has not diminished either: many of us add salt during cooking or at the table, and salt has a ubiquitous presence in pretty much every processed food.

Some salt 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. The evidence suggests that health consequences of bagfuls of salt in the diet can be quite unsavoury. Not surprisingly, the salt industry has also been vociferous in defending its commodity. However, despite the protestations of the salt-sellers, a sea of scientific research over the last 10 years supports the notion that salt can contribute to problems with high blood pressure.

 


Blood pressure is measured in millimetres of mercury (mmhg), and is expressed as two values, one over the other, eg 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 has long been seen as a major risk factor for heart disease and stroke. A recent study in the Lancet medical journal found that, in individuals aged 40 to 69, an increase in systolic blood pressure of 20mmhg was associated with a doubling in risk of death due to these conditions.

Studies suggest that reductions in salt intake might have important implications for public health. Recently, researchers from the Blood Pressure Unit at St George’s Hospital, London, assessed data from 29 trials examining the effect of salt reduction on blood pressure. The data suggests that if we halved our salt consumption, we would see meaningful reductions in blood pressure in the population. Relieving pressure in the circulation by reducing salt in the diet is expected to translate into a nine and 14 per cent reduction in deaths due to heart disease and stroke, respectively, in those suffering from high blood pressure. Interestingly, though, even those classified with normal blood pressure are likely to reduce their risk to some degree.

Most of the salt we consume comes our way into some unlikely places — cornflakes, weight for weight, are even saltier than seawater. Cutting back on our intake of pre-packaged foods, and the salt they contain, is one strategy almost certain to help preserve our health in the long term.

(The Guardian)