Difference between acidic food and acid-forming food

Difference between acidic food and acid-forming food

Pawel Malczewski
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Short summary

Acid-forming foods and acidic foods are unrelated, yet often confused. The confusion most commonly occurs when used in reference to “acid-ash hypothesis” which is based on acid-forming foods. For a quick answer click here.

Explanation

Acid-forming foods

Acid-forming foods contain inorganic minerals, most of which are negatively charged. They form acid in the body after digestion and absorption by contributing hydrogen ions. The more hydrogen ions in the liquid, the more acidic the liquid gets. It can be measured in the lab by calculating the net charge of the inorganic residue after burning organic matter or using pH urine tests or mineral contents of urine.

The concept of acid/base forming foods is the basis of the alkaline diet which claims that the the acid-forming foods are detrimental for health, while base-forming foods are health protective. (read more..)

Acid-forming food characteristics: (1)Koeppen BM. Advances in physiology education. American Physiological Society. Available here. (2)Bonjour JP. Nutritional disturbance in acid–base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney. British Journal of Nutrition / Volume 110 / Issue 07 / 14 October 2013, pp 1168-1177. Available here. (3)König D, Muser K, Dickhuth HH, Berg A, Deibert P. Effect of a supplement rich in alkaline minerals on acid-base balance in humans. Nutr J. 2009; 8: 23. Published online 2009 Jun 10. Available here. (4)Merc Manual. Acid-Base Regulation. Available here. (5)Welch AA, Mulligan A, Bingham SA, Khaw KT. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study. Br J Nutr. 2008 Jun;99(6):1335-43. Epub 2007 Nov 28. Available here.

  1. Not related to sour taste.
  2. Contain negatively charged minerals (acid-ash), such as phosphate, chlorine and sulfur.
  3. Ash can be measured either in a lab using the actual food or by urine tests after the food has been digested and absorbed.
  4. They contribute extra hydrogen ions to the body, resulting in a slight drop in blood pH which is quickly regulated by a number of acid-base balancing (buffering) mechanisms in the body, adjusting it back to an optimal pH. (read more..)
  5. One of the buffering mechanisms is via the kidneys. Kidneys filter extra acids and acid forming minerals that are then excreted through urine. The presence of these minerals lowers urine’s pH.
  6. Acid-forming measurement is used in acid-ash hypothesis which states that acid-forming foods, such as proteins (due to their high acid-ash contents), cause blood pH to drop and bones to release calcium to buffer this acidity. The hypothesis has been shown to have no scientific evidence supporting it.

Acidic foods

Acidic foods have a sour taste and are tested in their natural intrinsic form – before it is ingested, digested and broken down. Intrinsic food acidity has no relation with the pH of urine and can be tested by using an electronic device called a pH meter in liquefied food.

Acidic food characteristics: (6)Koeppen BM. Advances in physiology education. American Physiological Society. Available here. (7)Bonjour JP. Nutritional disturbance in acid–base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney. British Journal of Nutrition / Volume 110 / Issue 07 / 14 October 2013, pp 1168-1177. Available here. (8)König D, Muser K, Dickhuth HH, Berg A, Deibert P. Effect of a supplement rich in alkaline minerals on acid-base balance in humans. Nutr J. 2009; 8: 23. Published online 2009 Jun 10. Available here. (9)Merc Manual. Acid-Base Regulation. Available here. (10)Welch AA, Mulligan A, Bingham SA, Khaw KT. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study. Br J Nutr. 2008 Jun;99(6):1335-43. Epub 2007 Nov 28. Available here.

  1. Have a sour taste.
  2. Acidity (pH) is measured by an electronic device called a pH meter applied inside liquefied food. It measures the amount of free hydrogen ions which determine the level of acidity of the liquid. The more hydrogen ions there are, the more acidic the liquid is.
  3. Is not related to acidity changes in the blood or urine. (read more..)
  4. Acidic foods have a pH < 7. The closer to 0 pH that the food is, the more acidic it is. Most of the foods we eat are acidic (pH is below 7). (read more..)
  5. Acidic foods may worsen the symptoms of acid reflux in people who have been diagnosed with gastroesophageal reflux disease (GERD).
  6. Acidity or alkalinity of the ash is not necessarily related to the acidity or alkalinity of the food.
  7. An example of an acidic food with alkaline effect on the body is lemon.
    Lemon juice has pH = 2.2 which is highly acidic on its own, however after digestion and absorption by the body the remaining inorganic material (ash) contains mainly alkaline minerals. This net alkaline inorganic mineral content has an alkalizing effect on the urine pH.

NOTE: Results of urine pH and blood pH (or body alkaline-acid balance) is frequently confused. Urine pH is different from blood pH and the tests are different and unrelated.

Difference between acid foodic and acid-forming food

Conclusion

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Acidic foods and acid-forming foods exert a different effect on the body.

Acid-forming food may reduce urine pH. However, it has shown no impact on health, contrary to the ash-acid hypothesis.

Acidic food, for instance, is not associated with a body’s pH. Nevertheless, it is linked with a worsening of the reflux symptoms in people with GERD.

References   [ + ]

1. Koeppen BM. Advances in physiology education. American Physiological Society. Available here.
2. Bonjour JP. Nutritional disturbance in acid–base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney. British Journal of Nutrition / Volume 110 / Issue 07 / 14 October 2013, pp 1168-1177. Available here.
3. König D, Muser K, Dickhuth HH, Berg A, Deibert P. Effect of a supplement rich in alkaline minerals on acid-base balance in humans. Nutr J. 2009; 8: 23. Published online 2009 Jun 10. Available here.
4. Merc Manual. Acid-Base Regulation. Available here.
5. Welch AA, Mulligan A, Bingham SA, Khaw KT. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study. Br J Nutr. 2008 Jun;99(6):1335-43. Epub 2007 Nov 28. Available here.
6. Koeppen BM. Advances in physiology education. American Physiological Society. Available here.
7. Bonjour JP. Nutritional disturbance in acid–base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney. British Journal of Nutrition / Volume 110 / Issue 07 / 14 October 2013, pp 1168-1177. Available here.
8. König D, Muser K, Dickhuth HH, Berg A, Deibert P. Effect of a supplement rich in alkaline minerals on acid-base balance in humans. Nutr J. 2009; 8: 23. Published online 2009 Jun 10. Available here.
9. Merc Manual. Acid-Base Regulation. Available here.
10. Welch AA, Mulligan A, Bingham SA, Khaw KT. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study. Br J Nutr. 2008 Jun;99(6):1335-43. Epub 2007 Nov 28. Available here.

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