Is Collards Safe for Kidney Stones? (Safe)
mg oxalate
per serving
Serving: 1/2 cup (95 g)
Verdict: 🟢 Safe
Per 100g: 22 mg
Data: Harvard T.H. Chan SPH (2024)
Here's the takeaway: Collards earns a Safe rating (🟢) at 21 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 Collards poses no special concern.
Putting Collards in context: it lands below the category average of 27 mg. In the database, 80% of vegetables (219 of 271) fall in the 🟢 Safe group (under 25 mg oxalate/serving). The typical vegetables here averages 27 mg oxalate per serving, so Collards runs 23% below that baseline. That places it near the middle of the pack 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 vegetables rated Safe for a full side-by-side.
Why does the safe threshold matter?
The 25 mg cutoff comes from clinical guidance for stone formers. Below it, a food's oxalate contribution is small enough not to move the needle for most patients. Harvard's 2024 lab data sits behind these figures — direct measurements, not estimates. Collards comes in at 21 mg oxalate per 1/2 cup (Safe) in the measured database.
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. For Collards, the measured oxalate value is 21 mg per 1/2 cup (Safe).
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. Applied to Collards: 21 mg oxalate per 1/2 cup — Safe per Harvard (2024).
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. Collards comes in at 21 mg oxalate per 1/2 cup (Safe) in the measured database.