A healthy balance of acidic and alkaline foods in the diet is important for maintaining good health. Many diseases including osteoporosis and arthritis can be linked to too much acid in the diet and not enough alkaline substances, and most people eat far more acidifying foods than alkalinizing foods. The most alkalinizing foods tend to have higher levels of potassium and lower protein levels compared with similar foods.
Raisins
A 1995 study published in the Journal of the American Dietetic Association by Dr. Thomas Remer and Dr. Friedrich Manz helped determine the amount of acid or alkaline in dozens of different foods. They did this by determining foods' potential renal acid load, or PRAL, values. A positive PRAL is an acidifying food, and a negative PRAL is an alkalinizing food. The further the number is from 0, the stronger its acidifying or alkalinizing effect.
Raisins have the highest alkaline PRAL at -21.0 for 3.5 ounces. This means they are very alkalinizing. One likely reason for this is their high content of potassium, which averages 212 mg per ounce of raisins according to the USDA National Nutrient Database. Potassium salts found in vegetables are metabolized in the body to become the strong alkalinizing agent bicarbonate, according to L. A. Frassetto and colleagues in a 1998 article published in the American Journal of Clinical Nutrition. In this same study, it was found that foods that contain higher protein were more acidifying. Raisins have only 0.87 grams of protein per ounce.
Spinach
Spinach is also strongly alkalinizing, with a PRAL of -14.0 per 3.5 ounce serving. According to the USDA, raw spinach also contains a high level of potassium at approximately 159 mg per ounce and low protein at 0.81 grams per ounce. Both the high potassium and low protein help explain its alkalinizing effects. Boiled spinach still has a fairly high level of potassium at 130 mg per ounce.
Bananas
Bananas are known to be high in potassium, so it follows that they too have an alkalinizing PRAL of -5.5 per 3.5 ounce serving. According to the USDA, a small banana has an average of 362 mg of potassium and 1 gram of protein.
Celery
Raw celery has a PRAL value of -5.2 per 3.5 ounce serving, which is also strongly alkalinizing. According to the USDA, it contains a high level of potassium at 104 mg per medium-sized stalk and a low level of protein at 0.28 grams.
Carrots
Fresh raw carrots also have an alkalinizing PRAL value of -5.0 per 3.5 ounce serving. One medium carrot contains 195 mg of potassium and only 0.57 grams of protein according to the USDA.
References
- "Journal of the American Dietetic Association"; Potential Renal Acid Load of Foods and Its Influence on Urine pH; Thomas Remer Ph.D. and Friedrich Manz M.D.; July 1995
- U.S. Department of Agriculture: National Nutrition Database for Standard References
- "American Journal of Clinical Nutrition"; Estimation of Net Endogenous Noncarbonic Acid Production in Humans From Diet Potassium and Protein Contents; L. A. Frassetto et al.; September 1998
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