In October 2023, we visited three local pharmacies/drug stores in Freiburg, Germany and inquired about available citrate-based alkali supplements. In addition to that, we reviewed the available alkali supplements at several large online supplement retailers in Germany in early November 2023. Only citrate-based supplements were considered (defined as a citrate content > = 80% of the total alkali content). Supplements which included carbonates were only considered when the carbonate share was < 15% of the total content. To be considered eligible for this comparative review, supplements had to contain either potassium citrate, calcium citrate, magnesium citrate or any combination of these organic salts.
Supplement content (in g), the recommended daily dosage (RDD, in g) as well as the magnesium, potassium, sodium and calcium content of the respective supplements were reviewed. The PRAL was estimated per RDD with the following formula postulated by Remer and Manz [26 (link)]:
PRAL (mEq/RDD) = (0.49 * total protein content (g)) + (0.037 * phosphorus content (mg)) – (0.021 * potassium content (mg)) – (0.026 * magnesium content (mg)) – (0.013 * calcium content (mg)) -(0.041 * sodium content (mg)).
Sodium was added to the PRAL formula in order to increase the precision of our estimates, and because a few examined supplements contained sodium citrate (see results below), which also exerts alkalizing effects. For sodium, the conversion factor “0.041” was extracted from the work of Remer and Manz [26 (link)].
Moreover, we also calculated the so-called “total alkali load” (TAL) in mg, which is the sum of the following 4 alkalizing minerals: magnesium, potassium, sodium and calcium. The TAL (in mg) is not to be confused with the PRAL (in mEq), as the TAL reflects a (theoretical) indication of quantity.
In addition to that, we systematically captured the content of other minerals and vitamins included in each alkali supplement. Furthermore, we also reviewed whether the supplement was vegan (defined as not containing any animal-based components) or not, and whether the respective supplement was manufactured in Germany or not. In cases of doubt, we contacted the respective manufacturers by email and – if unsuccessful – by telephone. This information was collected to describe the examined dietary alkali supplements in as much detail as possible, allowing for a balanced and unbiased comparative analysis of the included products.
Supplement content (in g), the recommended daily dosage (RDD, in g) as well as the magnesium, potassium, sodium and calcium content of the respective supplements were reviewed. The PRAL was estimated per RDD with the following formula postulated by Remer and Manz [26 (link)]:
PRAL (mEq/RDD) = (0.49 * total protein content (g)) + (0.037 * phosphorus content (mg)) – (0.021 * potassium content (mg)) – (0.026 * magnesium content (mg)) – (0.013 * calcium content (mg)) -(0.041 * sodium content (mg)).
Sodium was added to the PRAL formula in order to increase the precision of our estimates, and because a few examined supplements contained sodium citrate (see results below), which also exerts alkalizing effects. For sodium, the conversion factor “0.041” was extracted from the work of Remer and Manz [26 (link)].
Moreover, we also calculated the so-called “total alkali load” (TAL) in mg, which is the sum of the following 4 alkalizing minerals: magnesium, potassium, sodium and calcium. The TAL (in mg) is not to be confused with the PRAL (in mEq), as the TAL reflects a (theoretical) indication of quantity.
In addition to that, we systematically captured the content of other minerals and vitamins included in each alkali supplement. Furthermore, we also reviewed whether the supplement was vegan (defined as not containing any animal-based components) or not, and whether the respective supplement was manufactured in Germany or not. In cases of doubt, we contacted the respective manufacturers by email and – if unsuccessful – by telephone. This information was collected to describe the examined dietary alkali supplements in as much detail as possible, allowing for a balanced and unbiased comparative analysis of the included products.
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