The current mainstream medical consensus is that high sodium diets are a cause of elevated blood pressure, and that lowering sodium intake will reduce blood pressure. As with all good lies, this viewpoint is based on a half truth, which has then been exaggerated to vilify sodium and create an artificial paradigm for the general public. Studies investigating healthy people do not show consistent results in terms of blood pressure lowering effects for low sodium diets. Such inconsistent results are typical in nutritional research where confounding variables exist. In the case of sodium research, the confounding variable that exist that cause inconsistent results in studies is likely the presence or absence of other electrolytes in the diet. Looking deeper into the issue, it becomes apparent that in healthy subjects high sodium diets are unable to cause rises in blood pressure unless a low potassium intake is also present. Therefore what is typically called a high sodium diet could equally be referred to as a low potassium diet.
That potassium shows associations with blood pressure has been evidenced in the nutritional literature and this observation has been widely reported in numerous studies. For example, in one study1, researchers investigated the influence of dietary potassium levels on blood pressure in 685 men and women aged 20 to 79 years. To do this the researchers used the popular 24-hour dietary recall method to collect information on the subject’s diets, and then used food tables to estimate their intake of potassium. After adjusting for age, the researchers reported a significant negative association between blood pressure and potassium intake. In other words, as the potassium intake of the subjects increased, the risk of that individual showing high blood pressure decreased. The association between potassium and blood pressure was still present even in those taking antihypertensive medication and after controlling for other dietary variables including calcium, alcohol, carbohydrates and fat.
The researchers showed that for every 10 mmol (400 mg) increase in the potassium of the diet, there was a concomitant decrease in blood pressure equivalent to 1.7 to 1.8 mm Hg systolic blood pressure. Fruits and vegetables are good sources of potassium and therefore it is likely that those subjects who had the highest intake of plant based foods had the lowest blood pressure. This is supportive of the health benefits of plant based foods such as fruits and vegetables which show protective effects against cardiovascular disease. Those subjects with the lowest potassium intake but were likely eating a more typical Western diet which is low in fresh fruit and vegetables and high in processed foods containing sodium. This explains the association between sodium intake and high blood pressure, because high sodium diets are by definition also low potassium diets. Lowering sodium intake without a concomitant increase in potassium will therefore likely not produce improvements in blood pressure.
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