The typical Western diet is a low quality diet consumed by many individuals in the developed nations of the Western Europe, North America and Australasia. In particular, the typical Western diet includes high amounts of refined and processed foods that may drive Western lifestyle diseases such as obesity, cardiovascular disease, cancer, dementia, type 2 diabetes and arthritis. Refined and processed foods are detrimental to the health because they supply energy, but do not contain the micronutrients and fibre required for human health. In addition, the typical Western diet is low in foods of plant origin such as fruits and vegetables. Such foods have been shown to contain high concentrations of phytochemical nutrients, many of which are bioavailable in humans. These phytochemical compounds, which belong to groups such as carotenoids and polyphenols, have been shown to have antioxidant effects that may protect from the oxidative stress that characterises many Western lifestyle diseases.
The low intake of plant foods and high intake of refined and processed foods in the typical Western diet has a number of other effects on human physiology. In particular consumption of processed foods increases the sodium content of the diet significantly, as salt (a source of sodium), is added to many processed and refined foods for its taste and preservative effects. In addition, the lack of plant foods lowers the potassium intake, as plants generally have very high concentrations of potassium and very low concentrations of sodium. Consuming the typical Western diet therefore creates a high sodium to potassium ratio in the diet of the individual and this can have severe health consequences, particularly on blood pressure. However, the high sodium to potassium ratio of the typical Western diet can also be a useful dietary marker to assess diet quality. For this reason associations between the sodium to potassium ratio of urine can be found with many Western lifestyle diseases including obesity.
For example, in one study1, researchers investigated the association between the urinary sodium to potassium ratio and obesity in a group of nearly 3000 North Americans. The results of the study showed that for every 3-unit increase in the urinary sodium to potassium ratio, total body fat increased by between 0.42 and 0.75 % depending on the statistical model used by the researchers. Subgroup analysis of the subjects showed that there was a significant effect for race in the relationship between the urinary sodium to potassium ratio and total body fat percentage. In this respects, African Americans had lower body fat percentages per unit increase in urinary sodium to potassium ratio compared to other races. As no mechanism exists to explain how high sodium low potassium diets could lead to obesity, it is likely that the association was confounded by the presence of low quality foods. Such foods are the likely causal factor in the observed obesity, and just so happen to possess high sodium to potassium ratios.
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