The effect of poor quality diet on cardiovascular disease is now fair well established. Refined and processed carbohydrates, particularly refined crystalline sugars and refined grains, cause a desensitisation in the insulin receptor and this causes insulin resistance. As insulin resistance worsens, dysfunctions within the liver develop, and this leads to disruption of lipid, carbohydrate and fat metabolism, ultimately causing fatty liver disease. The downstream changes caused by this disruption leads to a group of closely related metabolic disorders termed syndrome X or metabolic syndrome. One of the diseases associated with this metabolic disruption is cardiovascular disease. A number of dietary factors are known to protect from metabolic syndrome, most notably the avoidance of refined grains and sugars. In addition, trans fats may also exacerbate the detrimental changes seen in metabolic syndrome through inhibition of essential fatty acid pathways. Fibre, antioxidants and essential nutrients may also be protective.
The growing awareness that diet as a whole, rather than individual food, are the cause of disease has resulted in a paradigm shift. As a result a number of studies have looked at the benefit of dietary changes that incorporate wide ranging improvements to multiple aspects of food intake. This has lead to the development of a number of diet quality indexes that are aimed at providing a holistic approach to health improvements. For example, one study1 used such a holistic approach to alter the diet of a number of medically healthy non-smoking individuals aged 40 to 70 years. The dietary changes included a reduction in sugar intake, incorporation of more fatty fish (to provide essential fatty acids), a reduction of salt intake, a reduction in saturated fat and an increase in fruit and vegetable intakes. The subjects were also recommended to choose lean meats, avoid high fat dairy products, trans fats, sugar sweetened soft drinks and added salt at the table. Whole grain cereals were also emphasised.
The subjects followed the diet for 12 weeks and following the study a number of physiological and biochemical parameters that are considered markers for cardiovascular disease, were compared with control subjects who were given no dietary recommendations. The results showed that compared to the control subjects, those following the dietary change had significant reductions in systolic blood pressure, a reduction in the total to high density lipoprotein (HDL) cholesterol ratio, a reduction in C-reactive protein (a marker of systemic inflammation) and lower pulse wave velocity (suggesting vascular improvements). Although insulin sensitivity was not improved, the dietary guidelines group did lose 1.9 kg of body weight compared to the control group. These results suggest that dietary changes for just 12 weeks can improve cardiovascular risk profile in otherwise healthy individuals. The authors estimated that these changes would lower the risk of cardiovascular disease by about one third.
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