Are Tomatoes Acidic or Alkaline?
Alkaline, even though they taste sour. Fresh tomatoes have a PRAL of −4.2 per 100 g, and tomato paste is even strongly alkaline at −21.2.
Why tomatoes are alkaline
Tomatoes are rich in potassium and low in protein, so they land clearly in the alkaline range. That goes for fresh tomatoes as well as canned tomatoes (−4.1) and tomato juice (−4.3). The fruit acid you taste is broken down by your metabolism and doesn't count.
Cooking tomatoes down concentrates the potassium. Tomato paste reaches −21.2 per 100 g, and sun-dried tomatoes reach −53.8. Two tablespoons of tomato paste (30 g) in a sauce add about −6.4. That makes tomato sauce one of the easiest ways to pull pasta or pizza dishes toward the alkaline side.
Acidic or alkaline: PRAL, not pH
The PRAL (potential renal acid load) estimates what a food leaves behind after digestion. It is not the pH of the food itself: a lemon tastes sour, yet its PRAL is −4.0. If you are asking whether tomatoes are acidic because of heartburn or reflux, that is a question of pH and your stomach, which the PRAL does not measure; talk to your doctor about it.
Tomatoes in different forms: raw, cooked, processed
How the PRAL changes with state and product. All values per 100 g or 100 ml.
| Food | PRAL |
|---|---|
| Tomato (fresh) | −4.2 |
| Tomatoes, peeled (canned) | −4.1 |
| Tomato juice (raw) | −4.3 |
| Tomato paste (canned) | −21.2 |
| Sun-dried tomato (dried) | −53.8 |
Goes well with
Frequently Asked Questions
Are tomatoes alkaline even though they taste acidic?
Yes. Fruit acids are metabolized to CO₂ and water, and the potassium is what's left. That's why the PRAL is negative.
Is ketchup acidic?
Not by PRAL. Ketchup is alkaline at −6.5 per 100 ml because it's based on tomato paste. This doesn't rate its sugar content of around 20%.
Tomatoes and everything else on your plate: calculated automatically.
Basentracker adds up the PRAL of every meal and shows whether your day is in the alkaline range. Over 950 foods, photo scan, recipes, free.
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More vegetables & salad compared
All vegetables & salad with their PRAL: Vegetables & Salad table. Back to the overview Acidic or Alkaline?, or put together a meal in the PRAL calculator.
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.