How We Rate Foods

Every rating on this site is produced by the same transparent process. Here is the full method.

The three minerals

Ratings are based on three minerals that matter most in CKD: phosphorus, sodium and potassium. Protein, fiber, sugar, purine and oxalate are shown on food pages but never change a rating.

The daily limits

We use the CKD stage 3-4 daily limits from KDIGO/KDOQI guidance:

The tier rule

For each food, we take its phosphorus, sodium and potassium per 100 g, and divide each by the daily limit to get a percentage. The highest of the three percentages decides the tier:

• Below 15% — Kidney-friendly
• 15-25% — Moderate
• 25-30% — Limit
• Above 30% — Higher risk

For example, a banana has 358 mg potassium per 100 g, which is 358/2000 = 17.9% of the limit — the highest of its three minerals — so it is rated Moderate.

One adjustment: added phosphate

Foods that contain inorganic phosphate additives (common in processed drinks and packaged foods) are capped at Moderate even if their mineral percentages are low — because additive phosphate is absorbed almost completely, unlike natural phosphate. This follows KDIGO clinical practice guidelines to avoid phosphate additives in CKD.

Bioavailability labels

Food pages also show two transparency labels: phosphorus source (natural plant / animal / additive) and potassium form (whole food / processed). These describe absorption, not rating.

Where the numbers come from

Every per-100 g value on this site comes from USDA FoodData Central, the U.S. Department of Agriculture's primary nutrient database. Each food page cites its source fdc_id, so any rating can be traced back to the exact database row it was computed from. When USDA publishes survey updates, affected rows are re-pulled and re-rated.

The daily limits and the phosphate-additive rule are read from KDIGO and KDOQI nutrition guidance for CKD stages 3-4. General context on eating with kidney disease follows NIH NIDDK and National Kidney Foundation patient resources.

Ratings are data, not prescriptions. Your stage and labs always come first.

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