The Harvard Heart Letter has focused its entire November issue on nutrition, and offers advice aimed at unscrambling the mixed messages about what constitutes healthy eating.

Among its perspectives, the issue highlights:

• Fruits and vegetables: Along with exercise, fruits and vegetables are the closest thing to “a magic bullet” against heart disease. To get the most phytonutrients, choose foods in all colors. The Letter notes that a growing variety of frozen fruits and vegetables makes it easier to partake in the power of produce.
• Choose healthful sources of fat, carbohydrate, and protein: Many people are confused by widely promoted diet claims and contradictory research. The Letter’s bottom line: choose unsaturated fats and carbs with a low glycemic index.
• Four diets that have been tested in clinical trials: These are the dietary approaches to stop hyphenation (DASH) diet, a higher-protein diet called the OmniHeart diet, the cholesterol-lowering portfolio diet created by University of Toronto researchers and a Mediterranean-type diet. These four diets are much better for the heart than the average American diet, and each has its own subtle effects on various heart disease risk factors.