Nutrition labels are supposed to make healthy choices easier. But the Nutrition Facts label was designed for the general public — and if you have chronic kidney disease (CKD), some of its built-in guidance points you in exactly the wrong direction. Knowing where the standard label helps, where it misleads, and where it stays silent is one of the most useful skills on a kidney diet.
First, a quick refresher: %DV and the 5/20 rule
The U.S. Food and Drug Administration puts a "% Daily Value" (%DV) next to most nutrients. It's a quick way to judge whether a serving is high or low in something, using a simple rule of thumb:
- 5% DV or less = low in that nutrient
- 20% DV or more = high in that nutrient
That's handy — but %DV is built around general-population targets, and that's where kidney disease changes the picture.
Sodium: the one where the label agrees with you
For sodium, the standard advice and the kidney-diet advice line up: lower is better. The FDA's Daily Value for sodium is less than 2,300 mg per day, and it's flagged as a nutrient to get less of. Use the 5/20 rule — aim for foods closer to 5% DV, and be wary of anything at 20% DV or more. Many people with CKD are advised to go below 2,300 mg, so your personal target may be stricter.
Potassium: where the label can mislead you
Here's the big trap. The FDA lists a Daily Value for potassium of 4,700 mg and frames it as a nutrient most people should get more of, because for the general public, higher potassium can help lower blood pressure.
For many people with kidney disease, that advice is reversed. When kidneys can't clear potassium well, it can build up to dangerous levels. So if your care team has told you to limit potassium, ignore the "get more" framing and the %DV — instead, read the actual milligram number and weigh it against your limit, not the label's.
Watch out: Not everyone with CKD needs to restrict potassium, and some kidney-friendly diets are deliberately higher in it. Whether potassium is a "limit" or not is a decision for your dietitian based on your lab work — the label can't make that call for you.
Phosphorus: the one the label hides
Phosphorus is often the most important mineral on a kidney diet — and it's usually not listed on the Nutrition Facts label at all. Manufacturers generally aren't required to include it, so the panel can give you a false sense of safety.
This is where you have to switch from the Nutrition Facts panel to the ingredient list. The National Kidney Foundation recommends scanning ingredients for the letters "PHOS" — additives like phosphoric acid, sodium phosphate, and calcium phosphate. These added phosphates are absorbed almost completely by the body, far more than the phosphorus naturally found in food, which makes them especially worth avoiding.
Pro tip: Two similar products can look identical on the Nutrition Facts panel, but the one with no "PHOS" ingredients is usually the kidney-friendlier pick.
Don't forget the serving size
Every number on the label is per serving — and a small package often holds two or three servings. If a can lists 300 mg of sodium per serving and contains two servings, eating the whole can is 600 mg. Always check the serving size and servings-per-container, and multiply if you eat more than one.
Putting it together with PureLog
Reading labels is the skill; keeping a running tally against your limits is the habit. PureLog is built to do both, including the minerals other apps skip.
- Scan Nutrition Label and Scan Barcode (Premium) pull the printed values — including sodium and potassium — straight off the package. Manual Entry and Search Food are free.
- Because phosphorus often isn't printed, a scan can't catch hidden phosphate additives — so reading the ingredient list for "PHOS" stays essential. Where a phosphorus value is missing, PureLog flags estimated fields, and you can enter a value yourself.
- Your Today's Summary tiles show sodium, potassium, and phosphorus against your limits with a green/yellow/red bar, so you can see at a glance whether a food fits your day before you buy or eat it.
A quick label-reading routine
- Check the serving size first, and note how many servings you'll actually eat.
- Look at sodium — aim low (near 5% DV).
- Check the potassium milligrams against your own limit, if you have one — not the label's "get more" framing.
- Scan the ingredient list for "PHOS" to catch hidden phosphorus.
- Log it so the day adds up — and bring questions to your dietitian.
The bottom line
The Nutrition Facts label is a useful tool, but on a kidney diet you have to read it differently than everyone else: trust it on sodium, second-guess it on potassium, and don't rely on it at all for phosphorus — read the ingredient list instead. Get into that habit and the grocery aisle becomes a lot less risky.