Foods that are highly alkalizing are fruits and vegetables. These foodstuffs produce a negative PRAL (Potential Renal Acid Load) rating when the nutritional content is analyzed. For people interested in the alkaline acid diet and optimum pH balance of the body it is worth noting that within this group of alkali producing food, some produce has a more beneficial effect on the body than others. For example, according to the study by Remer and Manz, rasins are one of the most highly alkalizing fruits and spinach is a high alkaline vegetable, both being great for health. We must remember that it is not the amount of acid contained in fresh fruit that determines the acid alkaline balance but rather the pH of the ash after we have burned the food in our bodies.
What I was interested to discover was further details regarding high alkaline foods. There were two parts to this question regarding their health benefits. Firstly what are the highest alkaline fruits and vegetables that we can include in our diets? And secondly what is it about the nutritional content of these foodstuffs that cause them to have a strong base (alkali) forming effect? Knowing what these foods are may be useful in combatting the effects of acid foods.
Using the data from the study Potential renal acid load of foods and its influence on urine pH. the highest alkaline forming fruit, out of those measured, was raisins with a PRAL value of -21.0 while for vegetables the highest was spinach at -14.0. The negative values indicate alkaline forming foods while a positive value would indicate an acid forming potential. The formula that I will be using as the basis for the comparison of the alkaline properties of the fruit and vegetables I mention in this article follows:
For the sake of comparison I shall include the relevant nutritional information for apples, oranges and raisins to see if there are marked differences in any of the nutrients.
Raisins PRAL = 0.49*3.07 (protein) + 0.037*101 (phosphorus) – 0.021*749 (potassium) – 0.026*32 (magnesium) – 0.013*50 (calcium) = -11.9697
Apples PRAL = 0.49*0.26 + 0.037*11 – 0.021*107 – 0.026*5 – 0.013*6 = -1.9206
Oranges PRAL = 0.49*0.70 + 0.037*12 – 0.021*169 – 0.026*10 – 0.013*43 = -3.8897
The nutritional data for these fruits was taken from the United States Department of Agriculture site (see references). This is a great site regardless of what diet you are interested in. It contains details of the nutritional content of a wide variety of foodstuffs. The site makes it possible to determine the PRAL values for any alkaline acidic foods we are interested in. Using the PRAL Calculator that my brother wrote for me, you can check the Potential Renal Acid Load of any food you want. As can be seen from the figures above, even though raisins have higher levels of protein they also have much more potassium. This seems to be what accounts for the large negative value and therefore the highly alkalising effect they are reported as having. So a simple option to consider for those wanting to combat the effects of an acidic forming diet would be to eat more fruits in general but in particular, raisins.
One of the main goals for people interested in the alkaline acid diet who want health is to alkalize by eating healthy quantities of acid and alkaline ash foods. We must also remember that incorporating exercise into our lifestyle is an essential part to becoming healthier overall. Being aware of the high alkaline foods such as those discussed in this article offer ways to get an extra alkali kick.
References: USDA National Nutrient Database
Thomas Remer, Triantafillia Dimitriou and Friedrich Manz Dietary potential renal acid load and renal net acid excretion in healthy, free-living children and adolescents American Journal of Clinical Nutrition, Vol. 77, No. 5, 1255-1260, May 2003