he macrominerals calcium, sodium, magnesium and potassium are required for a number of important physiological functions in humans. In particular the minerals form a complex interactive system that provides the mechanisms by which nerve impulses are fired and regulated. Correct intakes are therefore pivotal to the function of the nervous and muscular system. Although humans can modulate excretion accordingly to some extent, the microminerals are required in a balanced dietary ratio in order to preserve health. Western diets are thought to disrupt this delicate macromineral ratio by supplying too much sodium, while not providing adequate magnesium, potassium or calcium. Although much has been made of the blood pressure raising effects of excess sodium, evidence does not support this contention in healthy individuals. However, long-term mineral imbalances may cause other problems such as muscle spasms, tetany, arrhythmias and blood pH changes.
The imbalance present between potassium and sodium in the Western diet is well reported in the nutritional literature. For example, in one study1, researchers used 24-hour diet recall questionnaires from over 12,000 adults aged over 20 years to ascertain the sodium and potassium intakes. Once collected the data was adjusted for individual variation to allow an estimate of the mean intake per population as a whole. The results showed that 99.4 % of United Stated adults consumed more that the recommended American Heart Association intake of sodium (1500 mg per day). In addition, 90.7 % of the population consumed more than the Institute of Medicine’s tolerable upper intake of 2300 mg per day. Over 3000 mg per day sodium was consumed by 60.4 % of the population. However, less than 2 % adults consumed the recommended intake for potassium of 4700 mg per day.
The reason that the Western diet provides inadequate intakes of potassium is because it is present mainly in fruit and vegetables. Magnesium too is also present in plant foods and is also therefore deficient for the same reason. Sodium and chloride however are present in abundance in convenience foods and as a result the Western diet is replete with sodium chloride. In addition, the high sodium intake is compounded by the low potassium intake, as renal excretion of sodium through the renal tubules is increased in the presence of adequate potassium. Low potassium intake is thought to lead to acidification of the blood, because the products of potassium salt metabolism are able to buffer rises in pH. Therefore low intake of potassium could be a cause of osteoporosis. For example, potassium citrate supplements have been shown to increase bone mineral density in women2.
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