There are a small number of foods, however, that may be listed on one chart as acid forming and on another as alkaline forming. For example, tomatoes, cranberries, carrots, lentils often fall into this gray area. How these foods are classified depends on the system used to calculate metabolic impact.
There are several different ways of calculating the metabolic impact of individual foods. In my book, The Acid Alkaline Food Guide, we explain the combination of scientific methods we used to determine the acid- or alkaline-forming impact of each food. (See pages 72-75; 2nd edition.) We used the best scientific information available today for assessing the acid- or alkaline-forming impact of foods. I am sure that over time new, more accurate ways to calculate these values will be discovered. In the meantime, we say “go by results” and don’t worry about contradictory classifications on a handful of specific foods. Go by results means eating a largely plant-based diet with adequate protein and then checking your first-morning urine pH each day to see the overall impact of the foods you eat and the supplements you use.