Is Soy Protein Isolate Acidic or Alkaline?
Soy protein isolate (raw) is strongly acid-forming: Positive PRAL: acid-forming after digestion.
Classification
Soy protein isolate reaches +67.0, several times the value of raclette cheese (+17.4), because it's almost pure protein. Production removes the carbohydrates, the fat and most of the alkalizing minerals, while the phosphorus stays. A shake with 30 g of powder adds about +20. If you use it, it's best to blend it with banana, berries or spinach.
In the Plant-Based Alternatives category, soy protein isolate (raw) ranks #21 of 21, sorted from alkaline to acid-forming. More alkaline options include Soy protein powder (+50.7), Seitan (+14.0), Tofu, plain (+8.3).
Acidic or alkaline: PRAL, not pH
On this site, acidic and alkaline refer to the PRAL (potential renal acid load). It estimates what a food leaves behind once it has been digested: a positive value is acid-forming, a negative value is alkalizing. That is different from the pH of the food itself: a lemon tastes sour, yet its PRAL is −4.0, so it is alkalizing. Your diet does not change your blood pH. It does change how much acid your kidneys have to deal with.
What balances soy protein isolate
100 g of soy protein isolate adds +67.0 to your daily balance. These three bring it back; the grams shown offset exactly this serving.
Frequently Asked Questions
Is soy protein isolate acidic?
It depends on what you mean by acidic. The pH describes the food itself, for example how sour it tastes. The PRAL describes what it leaves behind after digestion: Soy protein isolate (raw) has a PRAL of +67.0 per 100 g, so it counts as strongly acid-forming in your daily acid-base balance.
How much lamb's lettuce offsets 100 g of soy protein isolate?
100 g of soy protein isolate adds +67.0 to your daily balance. Lamb's lettuce (fresh) has −8.3 per 100 g, so about 810 g of lamb's lettuce offset this serving.
Do I have to avoid soy protein isolate on an alkaline diet?
No. What counts is the balance of the whole day, not a single food. Soy protein isolate is strongly acid-forming; with enough vegetables, potatoes and fruit on the same plate, the meal stays balanced.
Soy Protein Isolate logged, balance checked.
Basentracker adds up every meal automatically and shows whether your day is in the alkaline range. The same values as on this page, all 977 foods, photo scan, recipes.
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Compare all Plant-Based Alternatives: Plant-Based Alternatives table. Common questions are answered in Acidic or Alkaline?, and the PRAL calculator adds up a whole meal.
Source: Basentracker food database (PRAL according to Remer & Manz, calculated from protein, phosphorus, potassium, magnesium and calcium per 100 g). This information does not replace medical advice.