A balanced diet is to say that the totality of what one eats and drinks over the course of an average day provides one with adequate but not excessive amounts of the required “building blocks” (protein for amino acids, vitamins, and minerals) and energy yielding foods. A diet with a variety of meats, vegetables, starchy foods, and milk, will usually accomplish this without the need for supplements. Of course, needs vary with phases of life, degree physical exertion, allergies, and disease conditions that may arise.
At the following site you will find links that address these variables and take you to dietary recommendations accordingly. (The site is hosted by the U.S. Department of Agriculture; information is from medical university professionals; space to post questions is provided.
https://www.nal.usda.gov/fnic/dietary-guidance-0