Why are there so many discrepancies in the data about which foods are acid or alkaline forming?
To begin, most authorities agree that the vast majority of fruits, vegetables, nuts, and seeds are alkaline-forming, and that concentrated proteins in flesh foods, grains, and beans are acid-forming.
There are a small number of foods, however, that may be listed on one chart as acid-forming and on another as alkaline-forming. Tomatoes, cranberries, carrots, and 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 for assessing these values, and over time more accurate methods will surely be developed.
In the meantime, we say "go by results" and don't worry about contradictory classifications on a handful of specific foods. That means eating a largely plant-based diet with adequate protein, then checking your first-morning urine pH each day to see the overall impact of the foods you eat and the supplements you use.
