How Much Oxalate Is in Fish and Seafood?
mg oxalate
per serving
Serving: 4 oz (113 g)
Verdict: 🟢 Safe
Per 100g: 3 mg
Data: Harvard T.H. Chan SPH (2024)
The bottom line for Fish and Seafood: Safe (🟢), with 3 mg oxalate per serving — comfortably below the 25 mg safe cutoff. There's no need to limit it. Just keep your usual kidney stone basics in place: water throughout the day and calcium-rich foods at meals.
Putting Fish and Seafood in context: it lands well above the category average of 2 mg. In the database, 100% of seafood (55 of 55) fall in the 🟢 Safe group (under 25 mg oxalate/serving). The typical seafood here averages 2 mg oxalate per serving, so Fish and Seafood runs 94% above that baseline. That places it on the higher end for oxalate in its category. Why this matters: the gap between two Safe foods can be wide — one may hold 5 mg oxalate while another sits at 24 mg. The lower one leaves more room in your day. See all seafood rated Safe for a full side-by-side.
Why does oxalate per 100g matter?
The per-100g number lets you compare foods on an equal-weight basis, regardless of serving size. It's useful when two foods have very different typical serving sizes, or when you eat more or less than a standard serving. For Fish and Seafood, the measured oxalate value is 3 mg per 4 oz (Safe).
How accurate is the oxalate measurement?
These values come from Harvard's 2024 ion-chromatography analysis — the gold-standard method for oxalate. Real measured data rather than estimates. Sample-to-sample variation exists, but no published source is more dependable for food oxalate. Applied to Fish and Seafood: 3 mg oxalate per 4 oz — Safe per Harvard (2024).
How does this compare to other foods?
Anything under 25 mg per serving is Safe; 25-99 mg is Caution; 100 mg or more is Avoid. The category pages on OxalateWatch list foods side by side, so you can see where this one ranks. For Fish and Seafood, the measured oxalate value is 3 mg per 4 oz (Safe).