vidence is accumulating that refined carbohydrates are a cause of the lifestyle diseases that plague the Western health care system. In contrast, consumption of whole grain carbohydrates are considered protective of the same diseases. Refining the grains removes much of the micronutrient and fibre content with the bran and germ of the kernel, leaving mainly glucose from the endosperm. The problem with this is that the fibre and micronutrients aid the correct digestion of the glucose, and without these components the glucose absorption is accelerated. This can cause an increase in the requirement for insulin and raised the glycaemic index of the product. Not all refined grains have high glycaemic indexes, but generally, refining will raise the glycaemic index of a food from its whole grain equivalent. This also raises the glycaemic load, a measure of the glycaemic index per gram of food consumed.
A recent epidemiological study investigated the association between the glycaemic load and total carbohydrate content of the diet with breast cancer in 11,576 women aged 33 to 66 years. Comparison of the highest with lowest quintiles of glycaemic load and total carbohydrates showed a positive association with oestrogen receptor negative breast cancer in post menopausal women. The association between glycaemic load and oestrogen negative and progesterone negative breast cancer was even stronger in this groups. Therefore these results suggest that in some individuals, a high glycaemic load is associated with a higher risk of developing cancer. Mechanistically, high glycaemic index carbohydrates are though to cause disease because they stress the insulin system and lead to insulin resistance, and this can cause the development of metabolic syndrome, a disease characterised by inflammation and free radical tissue damage. Free radicals are implicated in the aetiology of a number of lifestyle diseases including cancer.
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