Hamilton, ON - Strong evidence supports the protective effect of a Mediterranean diet on risk of CHD, and overall diet pattern appears more important than individual foods [1].
These findings, from a review of close to 200 studies, are published in the April 13, 2009 issue of the Archives of Internal Medicine.
"We found strong evidence that a 'Western' diet—which is high in processed meats, red meats, butter, eggs, refined grains, and high-fat dairy products—is associated with an increased risk of CAD, so we could say [to patients]: 'You should consume less of those types of foods and gravitate more toward a "prudent" diet or a Mediterranean diet, which are both high in fruits and vegetables, legumes, whole grains, and fish,' " senior author Dr Sonia Anand (McMaster University, Hamilton, ON) told heartwire.
Although this message is not really new, what is new is the way that this review assessed the strength of the evidence, she noted.
The study also found strong evidence of increased CHD risk from consuming trans-fatty acids and foods with a high glycemic index such as white potatoes, sugar, white rice, and white bread.
Physicians should advise patients: "Lower your trans-fats, lower your saturated fats, but also watch for some of these simple carbohydrates, because they can have adverse effects as well,'' said Anand.
Diet dilemma
The relationship between diet and CHD has been studied for decades, yet there is still some confusion about which foods or diets are best, since cohort studies and randomized controlled trials have often produced discrepant results, the researchers write.
To examine the strength of the evidence supporting a causal link between diet and CHD, the researchers reviewed 146 prospective cohort studies and 43 randomized controlled trials (RCTs).
Studies were scored on how well they met four criteria of strength, consistency, temporality, and coherence. A score of 4 was considered strong evidence of a cause-and-effect relationship between dietary exposure and disease.
Dietary pattern vs single food
In the cohort studies, a Mediterranean diet—characterized by higher intake of vegetables, legumes, fruits, nuts, whole grains, cheese or yogurt, fish, and monounsaturated as opposed to saturated fatty acids—and a "prudent diet"—characterized by high intake of vegetables, fruit, legumes, whole grains, fish, and other seafood—were each associated with significantly lower risk of CHD. Similarly, strong evidence supported the benefits from monounsaturated fatty acids and foods such as vegetables and nuts and the harm from trans-fatty acids and foods with a high glycemic index.
In the RCTs, however, only the Mediterranean diet was strongly linked to risk of CHD.
"Our findings support the strategy of investigating dietary patterns in cohort studies and RCTs for common and chronic complex diseases such as CHD," the researchers write.
Study reinforces heart-healthy diet
Commenting on the results for heartwire, Dr Robert Eckel (University of Colorado, Denver) said that the study confirms previous notions about what a heart-healthy diet is all about.
It's not a matter of good foods and bad foods. It's what the overall quality of the diet is. "I think cardiologists need to increasingly make lifestyle-related issues an important part of their practice," he added. "This is another article reinforcing that a heart-healthy diet contains certain constituents and avoids certain constituents."
Concurring with the study authors, he noted: "Overall, the dietary pattern is what needs to be emphasized. It's not a matter of good foods and bad foods. It's what the overall quality of the diet is. The Western pattern is high in saturated fat, trans-fat, and cholesterol, whereas a Mediterranean diet and 'prudent' diet include more monounsaturated or polyunsaturated fats, and there is more fish consumption."
| No financial disclosures were reported. |
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