The Heart Institute of Spokane Diet Intervention and Evaluation Trial (THIS DIET)

Cardiovascular diseases (heart attack, stroke, and other vascular diseases) are major causes of mortality in developed countries. Although medicines and revascularization procedures prolong lives, rates of death and disability remain high. Lifestyle factors greatly contribute to risk. Yet, scientific data regarding the role of lifestyle change in prevention and treatment are limited. In the nutrition area, limitations include observational or uncontrolled study design, and focus on surrogate markers rather than on clinical outcomes.

Excess dietary fat has long been associated with cardiovascular diseases. Increased risk is related both to types of fat and calories from fat. Saturated fat, cholesterol, and trans-fatty acids have all been associated with adverse outcomes. Because fat is calorie-laden, high fat diets are commonly associated with weight gain and obesity. Low-fat diets have traditionally been recommended to control lipids and weight. However, these diets are high in carbohydrate and may actually be associated with weight gain if calories are not limited. Such diets have also been associated with worsening of hyperinsulinemia and insulin resistance and an adverse lipid pattern (low HDL cholesterol and high triglyceride levels). In contrast, increased intake of monounsaturated and omega-3 fats is associated with favorable effects on cardiovascular risk factors and markers including: endothelial function, lipids, and levels of insulin and glucose. Results have been consistent across various groups of high-risk patients, including those with hypercholesterolemia, diabetes, and hypertension. Most importantly, a Mediterranean style diet enriched in monounsaturated and omega-3 fats reduced death and cardiovascular complications after myocardial infarction (MI) in the Lyon Heart study.

The American Heart Association (AHA) Step 2 is a low-fat diet traditionally recommended for people with cardiovascular disease. The Mediterranean and AHA Step 2 diets differ primarily in the amount of monounsaturated and omega-3 fats, both of which are higher in the Mediterranean diet. Both diets are low in saturated fat (less than 7%) and cholesterol (less than 200 mg/d). Although the Lyon Heart Study compared a Mediterranean diet to a "prudent Western diet," a low fat diet similar to the AHA diet, the latter group did not achieve recommended intake levels of saturated fat or cholesterol. Furthermore, there was no longitudinal nutritional intervention in the low fat diet group. Therefore, the effect of nutritional intervention per se was not addressed.

Comparison(s): In survivors of a first MI, two longitudinal nutritional interventions, a Mediterranean style diet and an AHA Step 2 diet, will be compared. Both intervention groups will be compared to an untreated control group from our clinical database.