Are Fast-food French Fries Acidic or Alkaline?
French fries, fast-food (fried) are strongly alkaline: Negative PRAL: alkalizing after digestion.
Classification
Fast-food french fries are clearly alkaline at −11.4 because potatoes contain a lot of potassium and frying removes water, which concentrates the potassium per 100 g. A medium 120 g serving adds about −14. The value says nothing about the 239 kcal per 100 g, the fat or the salt. It only shows the mineral balance.
In the Meals & Fast Food category, fast-food french fries (fried) rank #2 of 118, sorted from alkaline to acid-forming. More alkaline options include Fried potatoes (with onions) (−12.0). More acid-forming are Guacamole (−8.7), Frozen french fries (−6.8), Potato salad (vinaigrette) (−4.6).
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.
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Frequently Asked Questions
Are fast-food french fries 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: French fries, fast-food (fried) have a PRAL of −11.4 per 100 g, so they count as strongly alkaline in your daily acid-base balance.
How much fast-food french fries do I need for a noticeable effect?
A meal (300 g) of fast-food french fries adds −34.3 to your daily balance. For comparison: an egg is around +5.4, a slice of cheese around +6. So one serving of fast-food french fries roughly offsets one of them.
Why are fast-food french fries alkaline even though they are not typical alkaline foods?
The PRAL depends on the minerals left over after digestion, not on taste or pH. French fries, fast-food provide more potassium, magnesium and calcium than phosphorus and protein, so the balance is negative (−11.4).
French Fries, Fast-food 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 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.