Is Onion Soup Acidic or Alkaline?
Onion soup (prepared) is alkaline: Negative PRAL: alkalizing after digestion.
Classification
Without a cheese topping, onion soup is slightly alkaline at −1.0 per 100 ml, because the onions (−2.4) release their potassium into the broth and bring hardly any protein. A 300 ml bowl adds about −3. Baked the classic way with white bread and a cheese crust, however, the French version moves toward neutral or above, and the cheese counts the most.
In the Meals & Fast Food category, onion soup (prepared) ranks #24 of 118, sorted from alkaline to acid-forming. More alkaline options include Bean soup (−1.1), Pea soup (−1.2), Tzatziki (−1.2). More acid-forming are Pumpkin soup (−1.0), Miso soup (−0.8), Mushroom soup (−0.7).
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.
Goes well with
Frequently Asked Questions
Is onion soup 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: Onion soup (prepared) has a PRAL of −1.0 per 100 ml, so it counts as alkaline in your daily acid-base balance.
How much onion soup do I need for a noticeable effect?
A meal (300 g) of onion soup adds −3.1 to your daily balance. For comparison: an egg is around +5.4, a slice of cheese around +6. So one serving of onion soup roughly offsets one of them.
Why is onion soup alkaline even though it is not a typical alkaline food?
The PRAL depends on the minerals left over after digestion, not on taste or pH. Onion soup provides more potassium, magnesium and calcium than phosphorus and protein, so the balance is negative (−1.0).
Onion Soup logged, balance checked.
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Compare all Meals & Fast Food: Meals & Fast Food 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.