The typical Western diet is associated with the development of Western lifestyle diseases. The detrimental health outcomes associated with consuming the Western diet relate to the presence of refined and overly processed foods as well as the absence of meaningful levels of essential nutrients. In particular, the typical Western diet contains high amounts of refined crystalline sugars that are increasingly being linked to the development of the metabolic syndrome, a cluster of disorders that centre on the presence of both peripheral and central insulin resistance. Sucrose is heavily implicated in the development of insulin resistance because it contains a moiety of fructose. In this regard both refined crystalline fructose and products that contain fructose such as high fructose corn syrup are also associated with the development of insulin resistance. Refined crystalline sugars may also have other detrimental effects including alterations in the sodium balance in the body as well as hormonal changes that may cause changes in blood pressure.
The blood pressure and sodium balance effects of sugars have been investigated in the nutritional literature. For example, in one study1 researchers hydrated a group of healthy subjects who had no history of high blood pressure. The subject then lay recumbent for 6 hours while their blood pressure changes and salt excretion rates were measured following the administration of various sugars. As the subjects voided urine the water content equivalent to the urine quantity was drunk by the subjects to maintain hydration. The subjects were fed glucose, fructose, galactose, lactose or sucrose 2 hours after the start of the experiment, and the blood pressure changes and salt excretion rates monitored. The hydration period cause a certain degree of natriuresis and kaliuresis in the subjects as might be expected. However, this was quickly abolished by the administration of glucose, fructose, sucrose and lactose. The most potent salt retentive agent was fructose given in isolation. There was no antinatriuretic or antikaliuretic effect observed with galactose.
In addition, both glucose and sucrose caused elevations in systolic blood pressure in the subjects that were significantly higher than the controls. These blood pressure changes lasted 2 hours following glucose ingestion and 1 hour following sucrose ingestion. Other research has shown that administration of fructose to healthy subjects can cause elevations in blood pressure (here). The reason for this may relate to an increase in sympathetic activity, which can then subsequently raise cardiac output and raise blood pressure. In this way constant activation of the sympathetic nervous system may be a side effect of sugar consumption when it is its refined crystalline state. The antinatriuretic effects of carbohydrates has been observed in other research studies and some speculation suggests that the sodium reabsorption from the distal tubules of the kidney is enhanced in the presence of higher levels of blood sugar because it is an energy requiring process. Because the medullary portion of the distal tubules of the kidney is not able to undergo gluconeogenesis it may require a source of glucose from the circulation.
Dr Robert Barrington’s Nutritional Comments: refined crystalline sugars in the diet of humans appear to produce a number of detrimental health outcomes. In nature sugar is usually present along with fibre and this prevents many of the detrimental effects of consuming sugars. Refining the sugars away from their fibre alters the absorption and metabolism kinetics of sugars and this results in chronic changes to metabolic regulation that may be drivers of Western disease. If sugars are able to raise blood pressure acutely, perhaps because of hormonal, natriuretic and kaliuretic effect, this may explain some of the detrimental effects from overconsumption of them in the diet.
RdB
