Is Seaweed Acidic or Alkaline?
Seaweed (dried) is strongly alkaline: Negative PRAL: alkalizing after digestion.
Classification
Dried seaweed is one of the strongly alkalizing foods. Drying leaves its potassium, magnesium and calcium on a fraction of the original weight, hence −18.6. You rarely eat more than a few grams, though, for example as a nori sheet around sushi or as flakes in soup, so its contribution to your daily balance stays small.
In the Vegetables & Salad category, seaweed (dried) ranks #2 of 110, sorted from alkaline to acid-forming. More alkaline options include Sun-dried tomato (−53.8). More acid-forming are Spinach (−12.9), Stinging nettle (−12.6), Spinach (−12.2).
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
Is seaweed 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: Seaweed (dried) has a PRAL of −18.6 per 100 g, so it counts as strongly alkaline in your daily acid-base balance.
How much seaweed do I need for a noticeable effect?
A serving (150 g) of seaweed adds −27.8 to your daily balance. For comparison: an egg is around +5.4, a slice of cheese around +6. So one serving of seaweed roughly offsets one of them.
Why is seaweed 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. Seaweed provides more potassium, magnesium and calcium than phosphorus and protein, so the balance is negative (−18.6).
Seaweed 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 Vegetables & Salad: Vegetables & Salad 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.