Many experts still claim that high salt diets cause blood pressure increases. However this viewpoint is disingenuous, and the contention that sodium chloride is the cause of high blood pressure is either deliberately propagandised or misguidedly believed. Animal and human studies have shown that increasing the sodium content of the diet does not lead to significant long term increases in blood pressure, and this is largely a result of the homeostatic mechanisms that allow for increases sodium excretion as intakes increase. The Western diet is a high sodium diet, and it is observed that consuming a Western diet increases the risk of blood pressure elevations. Many blame sodium for this effect, but there is no mechanism to explain how this effect could occur. It should also be noted that the Western diet is a low potassium diet, and so we can say that the sodium to potassium ratio of the Western diet is elevated. In the absence of adequate potassium, sodium may increase the risk of blood pressure changes in sensitive individuals.
Therefore modification to the macro mineral intake, which also includes calcium and magnesium in addition to potassium and sodium, may cause metabolic changes that result in blood pressure elevations in sensitive individuals. Most plant foods, including most fruits and vegetables, contain potassium and sodium in a ratio of around 20 to 1. In contrast, the Western diet may have a potassium to sodium ratio that favours sodium. In addition, the Western diet is relatively low in magnesium and calcium and this imbalance in macro mineral intake may be a driver of blood pressure changes. A number of salt substitutes are available that comprise of various mineral salts often in combination with sodium chloride. These products are designed to be used in place of regular table salt (sodium chloride) and have a taste that is almost indistinguishable from the former. Evidence suggests that such products may lower blood pressure because they rebalance the mineral intake in those with high sodium diets.
A number of studies have investigated the effectiveness of salt substitute (low sodium) products using randomised controlled in subjects with elevated blood pressure. A meta-analysis of such studies that pooled the results from these studies showed that salt substitutes reduced systolic blood pressure by 4.9 mmHg and diastolic blood pressure by 1.5 mmHg1. However the authors did note that the studies showed heterogeneity between subjects within the separate trials. This last point is interesting and important, because evidence suggests that certain groups are sensitive to sodium intake, whilst most are not. Using salt substitutes on those with high blood pressure selects for the individuals within a population that may be salt sensitive and therefore likely respond to changes in sodium. There is little evidence that addition of salt to the diet of healthy individuals or removal of salt from the diet of healthy individuals has any effect on measures of blood pressure. However salt substitutes may be a useful tool for those who are salt sensitive.
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