Scheda n. 2 

Lyon Diet Heart Study

N.B. Il contenuto di questa pagina proviene dal sito http://circ.ahajournals.org

(omissis)

Diet is a cornerstone of cardiovascular disease (CVD) prevention and treatment efforts. Step I and Step II diets are widely recommended as the first line of CVD intervention

At the core of this dietary guidance are the recommendations to decrease saturated fat and cholesterol and to consume more fruits, vegetables, and whole grain products. Information from an extensive database, especially regarding saturated fat, indicates that these diets significantly lower blood cholesterol levels, a major risk factor for CVD. Consequently, it is beyond debate that these diets reduce CVD risk. 

(omissis)

There is provocative evidence from the Lyon Diet Heart Study suggesting that a Mediterranean-style, Step II diet (emphasizing more bread, more root vegetables and green vegetables, more fish, less beef, lamb and pork replaced with poultry, no day without fruit, and butter and cream replaced with margarine high in -linolenic acid) has effects that may be superior to those observed for the usual Step I diet. 

(omissis)

Defining a Mediterranean-style diet is challenging given the broad geographical region, including at least 16 countries, that borders the Mediterranean Sea. As would be expected, there are cultural, ethnic, religious, economic, and agricultural production differences that result in different dietary practices in these areas and that preclude a single definition of a Mediterranean-style diet. Nonetheless, there is a dietary pattern that is characteristic of Mediterranean-style diets. This pattern emphasizes a diet that is high in fruits, vegetables, bread, other forms of cereals, potatoes, beans, nuts, and seeds. It includes olive oil as an important fat source and dairy products, fish, and poultry consumed in low to moderate amounts; eggs consumed zero to 4 times weekly; and little red meat. In addition, wine is consumed in low to moderate amounts. This dietary pattern is based on food patterns typical of many regions in Greece and southern Italy in the early 1960s. The Mediterranean-style Step I diet used in the Lyon Diet Heart Study was comparable to this pattern but uniquely different in that it was high in -linolenic acid.

The Lyon Diet Heart Study, a randomized, controlled trial with free-living subjects, tested the effectiveness of a Mediterranean-type diet  on composite measures of the coronary recurrence rate after a first myocardial infarction. Subjects in the experimental group were instructed by the research cardiologist and dietitian to adopt a Mediterranean-type diet that contained more bread, more root vegetables and green vegetables, more fish, fruit at least once daily, less red meat (replaced with poultry), and margarine supplied by the study to replace butter and cream. 

(omissis)

 Use of olive oil exclusively was not recommended because it was not acceptable as the only oil source in the diet. Wine in moderation was allowed with meals. Subjects in the experimental group participated in a 1-hour counseling session. In contrast, control subjects received no specific dietary advice apart from that generally provided by hospital dietitians or attending physicians.

(omissis)

The findings from the Lyon Diet Heart Study illustrate the potential importance of a dietary pattern that emphasizes fruits, vegetables, breads and cereals, and fish, as well as -linolenic acid within the context of a Step I diet. The clinical findings from the Lyon Diet Heart Study implicate risk factors beyond lipids and lipoproteins, which have historically been our primary targets of intervention. The fact that omega-3 fatty acids exert cardioprotective effects via multiple mechanisms (ie, prevent arrhythmia, have anti-inflammatory properties, decrease synthesis of cytokines and mitogens, stimulate endothelial-derived nitric oxide, are anti-thrombotic, are prostaglandin and leukotriene precursors, and inhibit atherosclerosis) suggest that they could have accounted for the cardioprotective effect observed. The unprecedented reduction in coronary recurrence rates, despite the fact that lipid/lipoprotein risk factors were comparable, clearly points to other important risk factor modifications as major influences in the development of CVD. There is a pressing need to identify these risk factor(s) and effective intervention strategies. Moreover, had this dietary pattern been prescribed with a Step II diet, as is presently recommended for individuals with CVD, the beneficial effects of the diet intervention could have been even more remarkable. Irrespective of this, a Mediterranean-style Step I diet can be followed by free-living people, although this diet plan has not yet been evaluated in a long-term primary prevention model.

It would be short-sighted to not recognize the enormous public health benefit that this diet could confer with adoption by the population-at-large if the findings are confirmed. Thus, the task at hand is to corroborate the results of the Lyon Diet Heart Study in both primary and secondary prevention models as expediently as possible and verify, as would be expected, that this dietary pattern is safe. In the meantime, we should take advantage of the possible opportunity to dramatically lower CVD risk in the population by widely recommending a Step I diet that features a dietary pattern that includes fruits, root vegetables (ie, carrots, turnips, potatoes, onions, radishes), leafy green vegetables, breads and cereals, fish, and foods high in -linolenic acid such as vegetable oils (ie, flaxseed, canola), vegetable oil products (ie, salad dressing and margarine made with nonhydrogenated oils high in -linolenic acid), and nuts and seeds (walnuts and flaxseed).

(omissis)