The following post is an excellent source for links to the discussion of healthy diets. It is a brief summary of what nutrition science “knows” at the present time.
For the complete discussion found in the Journal of the American College of Cardiology (March, 2017), click HERE. It is a long article; however, it provides a lot of details on the latest recommendations about “healthy” diets and the research behind them. It can be read as a PDF.