Early investigations of one's relationship between food and heart disease linked high levels of serum cholesterol to increased consuming bad fats, and subsequently, an elevated rate of coronary heart disease. This led to the American Heart Association's recommendation to limit fat intake to less than 30% of daily calories, bad fats to 10%, and cholesterol to actually 300 mg each day.
"Nearly all clinical trials within the 1960s, 70s and 80s compared usual diets to those characterized by low total fat, low saturated fat, low dietary cholesterol, and increased polyunsaturated fats," says study co-author James E. Dalen, MD, MPH, Weil Foundation, and University of Arizona College of Medicine. "These diets did reduce levels of cholesterol. However they didn't reduce the incidence of myocardial infarction or coronary heart disease deaths."
Carefully analyzing studies and trials from 1957 to the current, investigators discovered that the whole diet approach, and specifically Mediterranean-style diets, work well in preventing heart disease, even though they may not lower total serum or LDL cholesterol. The Mediterranean-style diet is low in animal products and saturated fat, and encourages intake of monounsaturated fats found in nuts and olive oil. In particular, the diet emphasizes consumption of vegetables, fruit, legumes, whole grains, and fish.
"The potency of combining individual cardioprotective foods is substantial — and maybe even stronger than many of the medications and procedures that have been the focus of latest cardiology," explains co-author Stephen Devries, MD, FACC, Gaples Institute for Integrative Cardiology (Deerfield, IL) and Division of Cardiology, Northwestern University (Chicago, IL). "Results from trials emphasizing dietary fat reduction were a disappointment, prompting subsequent studies incorporating a whole diet approach with a more nuanced recommendation for fat intake."
Based on the data from several influential studies, which are reviewed in the article, Dalen and Devries concluded that emphasizing certain food groups, while encouraging people to decrease others, is more cardioprotective and overall better at preventing heart disease than a blanket low-fat diet. Encouraging the consumption of olive oil over butter and cream, while increasing the amount of vegetables, fruits, whole grains, nuts, and fish promises to be more effective.
"The last fifty years of epidemiology and clinical trials have established a clear link between diet, atherosclerosis, and cardiovascular events," concludes Dr. Dalen. "Nutritional interventions have proven that a 'whole diet' approach with equal consideration to what is consumed as well as what is excluded is more effective in preventing coronary disease than low fat, low cholesterol diets."