By now we know that certain types of food do more for our health than others, but when it comes down to it, a lot of the research we read states that a particular item "may" promote heart health. Researchers sorted through 50 years of studies to weed out the definites from the maybes and discovered that only some diets claiming heart-healthy benefits are supported by strong evidence.
They found that the Mediterranean diet, incorporating plenty of vegetables, legumes, fruits, nuts, whole grains, cheese or yogurt, and fish, legitimately promotes heart health, and diets rich in vegetables and nuts also serve to lower your risk for heart disease. While there's some evidence about the ability for omega-3 fatty acids, whole grains, alcohol, vitamins E and C, beta carotene, folate, fruit, and fiber to positively affect heart health, the jury is undecided on whether or not these elements live up to the claims.
While more research needs to be done to qualify those dietary factors as being heart healthy, there is conclusive evidence that diets high in red meat, butter, refined grains, and high-fat dairy products, high-glycemic index foods, and trans-fatty acids are harmful to heart health. If you're concerned about heart health, revising your diet to resemble the typical Mediterranean diet could be a good place to start.