Is Black Walnut Hull Extract Safe for Kidney Stones? (Safe)
mg oxalate
per serving
Serving: 1 serving (100 g)
Verdict: 🟢 Safe
Per 100g: 3 mg
Data: Harvard T.H. Chan SPH (2024)
Here's the takeaway: Black Walnut Hull Extract earns a Safe rating (🟢) at 3 mg oxalate per serving. Being under 25 mg means it fits comfortably in everyday eating. Keep your usual habits — adequate fluids and calcium in meals — and Black Walnut Hull Extract poses no special concern.
Putting Black Walnut Hull Extract in context: it lands well below the category average of 34 mg. In the database, 56% of nuts & seeds (29 of 51) fall in the 🟢 Safe group (under 25 mg oxalate/serving). The typical nuts & seeds here averages 34 mg oxalate per serving, so Black Walnut Hull Extract runs 92% below that baseline. That places it among the lower-oxalate options 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 nuts & seeds rated Safe for a full side-by-side.
Why does the safe threshold matter?
The 25 mg line is the reference point clinicians use to separate everyday foods from ones that need caution. Every value on this page traces back to Harvard's 2024 lab analysis, so the threshold is applied to measured data rather than estimates. Applied to Black Walnut Hull Extract: 3 mg oxalate per 1 serving — Safe per Harvard (2024).
Can I eat this food every day?
If it's in the Safe zone (under 25 mg/serving), yes — it can be a regular part of your diet. For Caution or Avoid foods, frequency matters. Rotate them with lower-oxalate options throughout the week. Black Walnut Hull Extract comes in at 3 mg oxalate per 1 serving (Safe) in the measured database.
Where does the oxalate data come from?
Every oxalate figure is sourced from Harvard T.H. Chan SPH (2024), distributed via the OHF database. The values come from actual lab measurements of the foods — not from database averages or estimates. Black Walnut Hull Extract comes in at 3 mg oxalate per 1 serving (Safe) in the measured database.
Should I also check sodium and calcium?
Yes — oxalate alone doesn't decide stone risk. Sodium pushes more calcium into urine, and calcium from food (not supplements) helps bind oxalate during digestion. The main food page covers sodium and calcium alongside oxalate. For context, Black Walnut Hull Extract measures 3 mg per 1 serving, rated Safe.