Journal Name:
Public Health Nutr.
Article Title:
The Mediterranean diet: science and practice
Date Written:
2006
Volume:
9
Number:
1A
Page:
105
Author(s):
Willett, W.C.
Article:
Both epidemiologic and metabolic studies suggest that individuals can benefit greatly by adopting elements of Mediterranean diets. Early work published in the landmark Seven Countries Study, noted that among the 14 populations followed within various European regions, an approximately 10-fold difference in rates of heart disease was observed between Northern and southern countries. These differences were later attributed to diet and in particular, a “Mediterranean” dietary pattern which is characterized by whole-grain breads, pasta, brown rice; fruits; vegetables; and low-fat or nonfat dairy products. The diet includes a moderate amount of wine and frequent consumption of olives and olive oil (which like canola oil is very high in monounsaturated fatty acids), and omega 3 fatty acids (again found in moderate amounts in canola). In addition, the diet is also characterized by low levels of saturated fats.
Nutritional recommendations have advanced over the past two decades from all fat is bad – to the current notion that healthy oils are an extremely important component in heart health diets. This finding has been reproduced repeatedly, and has become an important element in understanding the health benefits of the Mediterranean diet.
During the last 20 years, research on the aetiology of CHD has shown that the effects of diet may be mediated by many different pathways. Initially, the emphasis was almost entirely on serum total cholesterol. Recently nutritional scientists have shown a greater appreciation of the importance of HDL-C (which canola oil can increase), triglycerides (which are reduced following canola consumption), and other lipid fractions. The effects of canola oil based diets can also favorably moderate thrombotic tendency, insulin resistance, inflammation, endothelial dysfunction, and ventricular arrhythmia.
Research now supports the observations that compared to carbohydrate, monounsaturated fat, and higher intakes of omega 3 fats are related to lower risk of CHD. The adverse effects of trans fat and the apparent beneficial effects of polyunsaturated fat are substantially greater than might be anticipated by only their effects on HDL and LDL cholesterol. Less studied than omega-3 fatty acids from fish, lower rates of CHD, both fatal and non-fatal, have been seen with higher intake of canola and flax based omega 3 alpha-linolenic acid. During the last few years a shift away from an emphasis on low-fat diets has been occurring. For example, the American Heart Association has recently noted that ‘The diet high in unsaturated fat (up to 35% calories from unsaturated fat plus up to 10% of calories of saturated fat) can be a viable alternative to a diet that is low in total fat’. A 2002 Institute of Medicine/National Academy of Sciences report emphasized the type of fat rather than the amount of fat, and allowed intakes of up to 35% of calories.
Similarly, the 2005 US Dietary Guidelines have moved away from an emphasis on low fat intake, suggesting a range of 20–35% of energy from fat and strongly emphasizing the need to reduce trans fat intake. As a result of such recommendations, canola oil and olive oil consumption has increased many-fold from the time when it was only a minor occupant of grocery store shelves.
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