With the exception of pure water, all foods can be classified as alkaline-forming or acid-forming in the body, depending on the nature of the compounds they produce when metabolized. Cells and tissues require a slightly alkaline environment for proper function, so the body buffers and removes acidic residues left by acid-forming foods. Regular consumption of acid-forming foods can cause acid buildup in bodily tissues, causing chronic low-grade metabolic acidosis, a condition distinguished by having a slightly acidic body pH.
Acid Vs. Alkaline
A food’s acid content is reflected in its value on the pH scale, which runs from 0 to 14. Acidic foods have values below 7. Low-acid foods are valued above 4.6, while high-acid foods have values at or below 4.6. A food’s pH value doesn’t indicate its pH nature in the body — the mineral compounds it produces through the metabolic process are what define it as acidifying or alkalizing. Foods are acid-forming when they break down into sulfur, phosphorus or chlorine, all of which contribute acidic residues.
Processed Foods
Processed and refined foods top the list of most acid-forming foods, according to the "Acid Alkaline Food Guide” and “The pH Balance Diet.” All forms of refined sugar are highly acid-forming in the body, making any food product that contains added sugar very acidifying. Likewise, because wheat and most other grains are acid-forming, grain-based products that contain added sugar produce high amounts of acidic residues. Cookies, muffins, pies, cake, bread, pasta, crackers and cereal are a few highly acid-forming processed foods.
High-Protein Foods
Beef, lamb, pork, poultry, fish and seafood are moderately to highly acidifying because they’re rich sources of phosphorus and sulfur-containing amino acids, both of which produce acidic residues. While most fish, seafood, pork and poultry are moderately acid-forming, beef and beef products such as hamburgers and beef sausage tend to be highly acidifying. Cow’s milk and other bovine dairy products are also acidifying. Highly processed cheeses tend to be the most acid-forming, while milk and younger cheeses are only slightly acid-forming. Goat- and sheep-derived dairy products, however, are slightly alkalizing.
Acidifying Beverages
Regular and diet soft drinks are among the most acid-forming of all beverages, due to their caffeine, phosphoric acid content and added sugar or artificial sweeteners. According to the "Acid Alkaline Food Guide,” it takes 32 glasses of alkalizing mineral water to neutralize the acidifying effects of one 8-oz. soft drink. Most alcoholic beverages are also highly acid-forming in the body. Exceptions include wine and darker ales, beers and malt liquors, which are only moderately acid-forming. Coffee is another highly acidifying drink that’s made even more acidifying by adding sugar, artificial sweeteners, milk or cream.
Considerations
Many nutritious foods are slightly acid-forming in the body, including milk, yogurt, cottage cheese and most legumes, nuts and whole grains. Whole wheat, brown rice, barley, rye and corn are all acid-forming, as are all nuts, with the exception of almonds and chestnuts, according to “The pH Balance Diet” and the "Acid Alkaline Food Guide.” Lentils are alkalizing, but most other legumes are slightly acid-forming. A diet that limits well-chosen acid-forming foods to 20 to 30 percent of total intake supports a healthy, balanced body pH.
References
- “Encyclopedia of Healing Foods”; Michael Murray et al.; 2005
- “The pH Balance Diet”; Bharti Vyas et al.; 2007
- “The Acid Alkaline Food Guide”; "Dr. Susan Brown et al.; 2006
- “Alkalize or Die”; Dr. Theodore Baroody; 1991
- Oklahoma State University; "The Importance of Food pH in Commercial Canning Operations"; William McGlynn
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