How to Read Food Labels With CKD: Sodium, Phosphorus and Potassium
This article is general information. Your nephrologist or renal dietitian knows your lab results and can tell you what is right for you.
A food label is a small piece of paper with a lot of information, and in a supermarket aisle it is easy to feel lost. This article walks through a label in the order a shopper actually uses it: first the ingredients, then the numbers, then the claims on the front. It gives general information only. The limits that apply to you are set by your nephrologist or a renal dietitian, based on your blood tests.
Start with the ingredient list
Ingredients are listed by weight, from the most to the least. The National Kidney Foundation (NKF) suggests two quick checks here. First, notice whether salt appears among the first few ingredients, which means the food contains a lot of it. Second, look for any word that contains “PHOS”, such as phosphoric acid or tricalcium phosphate.
That second check matters because phosphorus is not required on the Nutrition Facts label, so a food can contain it even when the number is missing. NIDDK explains that phosphorus additives are the primary source of phosphorus for many people, and the NKF adds that the body absorbs phosphate additives more readily than the phosphorus found naturally in food.
A third word to look for, if you have been told to watch your potassium, is “potassium chloride”. The NKF notes that it is common in low-sodium products, and that potassium added to food is absorbed more readily than the potassium that occurs naturally.
Then look at the serving size
Every number on the label refers to one serving, and the serving printed on the package may be different from the portion in your own kidney diet plan. The NKF advises checking with your kidney dietitian about portions. If you eat two servings, you take in double the sodium, potassium and everything else on the label.
Then the numbers
For sodium, NIDDK explains that a % Daily Value of 5% or less per serving means low in sodium, and 20% or more means high. The NKF gives a per-serving figure for a lower-sodium food in its label guide: no more than 240 milligrams per serving. It also offers a rule of thumb: the milligrams of sodium should be lower than the calories in the serving.
For potassium, the NKF label guide mentions a figure of no more than 200 milligrams per serving for foods that are lower in potassium, and says to ask your dietitian how much potassium you need each day.
These are the figures those pages give for label shopping. They are not your personal targets. NIDDK says that many people with CKD need to limit sodium more than the general adult limit, and that the right amount of potassium is individual. Your care team may give you different numbers.
Finally, the claims on the front
Phrases such as “low sodium”, “no salt added” and “unsalted” can point you to lower-sodium choices, according to NIDDK. They are a starting point, not the whole story. A product can be low in sodium and still contain potassium chloride or a phosphate additive, so the ingredient list remains the place to confirm.
Where salt and additives tend to hide
NIDDK names several groups of foods that are often high in sodium or phosphorus: canned and some frozen foods, processed and deli meats, chips and crackers, flavored drinks, and sauces such as ketchup, soy and teriyaki. Its general advice is to limit packaged and processed foods, to cook from scratch when you can, and to season with herbs, spices or lemon juice instead of salt.
Make it a habit, not a chore
Reading every label on every trip would wear anyone out. A gentler way is to check the few foods you buy again and again, once, and then remember what you found. Keep a short note on your phone, and bring it to your next appointment. Your dietitian can tell you which items matter most for you and which can stay on the list. If you are not sure what to ask, our article on questions to ask your nephrologist can help, and the basics of each mineral are in Kidney-Friendly Eating Basics.
From the label to the kitchen
The less packaged food you buy, the fewer labels you have to decode. That is where cooking at home comes in. Our Facebook group is a friendly place to swap everyday meal ideas, and Don’s Food Press publishes cookbooks with easy, kidney-friendly recipes for stage 3.
Related reading
Sources
- National Kidney Foundation: Your Guide to the Nutrition Facts Label (last updated January 2023)
- NIDDK: Healthy Eating for Adults With Chronic Kidney Disease (reviewed January 2025)
What is the first thing you look at on a label? Tell us in the group.
You are not alone with this. Tell us in the group, where people share what works for them and cheer each other on.
Join the group See the books