Not all carbohydrates are created equally. Carbohydrate foods are a broad category that includes sugars and starch, and within theses groups there is a large heterogeneity in structure and nutritional values. Increasingly it is being shown that carbohydrates can be split into disease causing and disease preventing categories. In the latter category, whole grains have been shown to be beneficial to the health, perhaps because they contain their original phytonutrient and essential nutrient components and because they produce lower glycaemic index responses compared to refined alternatives. The glycaemic response to carbohydrates is important because rapid and large increases in blood sugar overloads the cells with energy and this then facilitates a decrease in insulin sensitivity, subsequently leading to raised levels of fasting insulin. As insulin is able to interfere with the essential fatty acid pathways through allosteric inhibition of enzymes, this may lead to an environment characterised by chronic inflammation.
Researchers have investigated the association between carbohydrates and inflammation in epidemiological studies. For example, in one study1 researchers assessed the association between the quality of carbohydrates during adolescence and subsequent low grade inflammation in adulthood. Dietary records were used to assess the carbohydrate content of the diet and blood samples were taken and the plasma analysed for markers of inflammation including C-reactive protein, interleukin 6 and interleukin 18. The results of the study showed that a higher intake of higher glycaemic index carbohydrates (a higher glycaemic load) during puberty was associated with an increased concentrations of interleukin 6. Glycaemic index and sugar intake were not independently associated with inflammation during puberty. A higher intake of high glycaemic index carbohydrates and a lower intake of whole grain carbohydrates were associated with higher interleukin 6 concentrations subsequently in adulthood.
These data suggest therefore that higher intakes of high glycaemic index carbohydrates are associated with increased levels of chronic low grade inflammation, the latter being a likely cause of or contributory factor in the development of Western lifestyle disease. This may suggest that high glycaemic index carbohydrates are a cause of chronic low grade inflammation, and certainly there is good scientific evidence from well designed studies to support this view. For example, clinical studies that have exchanges high glycaemic index refined carbohydrates in the diets of subject for whole grain alternatives have observed a lowering of inflammatory markers. Further, there is good evidence that dietary practices in infancy, childhood and young adulthood can play a significant influence on subsequent health as an adult. However the high glycaemic index carbohydrate consumption in adolescence could also be a marker for a lower quality diet, and these poor eating practices may continue into adulthood, creating low grade inflammation.
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