Dietary patterns and health

Until recently, much of the research exploring the role of nutrition on human health has concentrated on single compounds. While this approach has provided information about e.g. the effects of various vitamins and minerals on human health, it has also limitations. Humans do not eat single nutrients but foods. These foods provide complex mixture of nutrients which may have additive or synergistic effects on health. Nutrients also tend to correlate with each other, e.g. cocoa contains hundreds of different nutrients, and thus in epidemiological studies separating the effect of a single compound is problematic. Also, in most cases the effect of a single compound may be relatively small to be detected in epidemiological studies. In contrary, if such an association is detected it may be simply result of a change, common problem related with multiple testing.

Food or dietary pattern oriented studies avoid some of the fundamental challenges of the studies assessing the role of single nutrients. Such studies provide also practical information for the public and to be used to create dietary guidelines. Therefore the effects of foods or dietary patterns should be studied in a parallel to those of single nutrients.

Dietary patterns can be classified into three approaches; factor analysis, cluster analysis, and dietary indices. Factor and cluster analysis are ‘a posteriori’, created based on the dietary patterns found in the particular study. Dietary indices, on the other hand, are ‘a priori’ as they are created based on the current knowledge about the ‘healthy diet’ or other pre-defined hypothesis. In these studies the effects of e.g. dietary guidelines or alternative patterns such as ‘Mediterranean diets’ on health can be tested in a population level.

Several studies have examined the relation between various dietary patterns and the risk of chronic diseases such as CVD, type II diabetes, and cancer. In general, these studies have provided stronger association when compared to those assessing a single nutrient. For CVD dietary patterns characterized as ‘prudent’,i.e. rich-in vegetables, fruits, legumes, whole grains and fish, have been to be found to associated with a 20-30% reduced risk of CVD and type II diabetes, and less strongly with cancer. Contrary, patterns defined as ‘western’ that are high in processed meats, red meat, butter, high-fat dairy, eggs, and refined grains have been found to be associated with an increased risk of chronic diseases.

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