Phosphorus Explained by a Renal Dietitian 

Have you been told to watch your phosphorus because of your kidney disease?

I’m here to help you understand why phosphorus matters, where it comes from, and how you can make simple choices to improve your health outcomes!

My name is Candace Mooney and I’m a Renal Registered Dietitian.

Let’s get started! 

What Is Phosphorus?

Phosphorus is an essential mineral found in your bones, teeth, and cells. Your body uses phosphorus to support healthy bones and teeth, make energy, repair cells, and maintain normal acid-base balance. It also works with calcium and vitamin D to support bone health. (1)

So, phosphorus isn’t something we want to completely avoid. Your body needs it!

What does phosphorus have to do with your kidneys?

Your kidneys help regulate the amount of phosphorus in your body. When your kidneys are working properly, they remove extra phosphorus through your urine.

When you have chronic kidney disease (CKD), your kidneys may not be able to remove phosphorus as effectively. This can cause phosphorus to build up in your blood. (2)

In CKD, phosphorus also matters for your heart and blood vessels. Higher phosphorus levels can contribute to vascular calcification, a process where calcium-phosphate deposits build up in the walls of blood vessels. This can make arteries stiffer and is associated with a higher risk of cardiovascular disease in people with CKD. (3)

This is why phosphorus becomes something we pay closer attention to when kidney function declines.

Phosphorus Recommendation for Kidney Disease

When I work with someone who has CKD, I don’t want to simply give them a list of foods they can’t eat. I want to look at where their phosphorus is coming from, how much is being absorbed, and what their individual lab results show.

So, does this mean you need to avoid every food that contains phosphorus?

No!

Instead, I want you to understand that the source of phosphorus matters.

KDIGO specifically notes that it is reasonable to consider whether dietary phosphate comes from animal foods, plant foods, or additives when making dietary recommendations for people with CKD. (4)

Let’s look at these a little closer before I give you my recommendation.

Types of Phosphorus

Your body doesn’t absorb all phosphorus at the same rate. This is the most important thing to understand about phosphorus.

Natural Phosphorus

Phosphorus naturally occurs in foods such as:

• Milk, yogurt, and cheese
• Meat, poultry, fish, and eggs
• Beans and lentils
• Nuts and seeds
• Whole grains

Phosphorus naturally found in food is absorbed at about 40–70%.

Animal sources generally fall in the higher absorption rate than plant sources. 

Plant-based phosphorus is often bound to phytate, which makes some of it less available for absorption so it usually falls in the lower percent of absorption rate. 

I rarely recommend avoiding plant based foods because of phosphorus content and usually encourage their consumption.

Added or inorganic phosphorus is absorbed much more readily, at about 80–100%! (5)

What Is Added (Inorganic) Phosphorus?

Added (inorganic) phosphorus is different from the phosphorus that naturally occurs in food.

Food manufacturers add phosphate ingredients for different reasons. They can help with things like texture, moisture retention, shelf life, flavor, leavening, color, and food stability. (6)

The important part for someone with CKD is that phosphorus from additives is very readily absorbed, at about 80–100%. This means your body can absorb much more of the phosphorus from additives compared with phosphorus naturally found in many foods.

And these additives are more common than you might think.

Researchers reviewed 2,394 top-selling grocery products and found that approximately 44% contained phosphorus additives. These additives were especially common in prepared frozen foods, dry mixes, packaged meats, breads and baked goods, soups, and yogurt. Meals made mostly from foods containing additives provided about 736 mg more phosphorus per day than meals made with additive-free foods! (7)

This is one reason I pay particular attention to added phosphorus when I work with someone who has CKD.

My Phosphorus Recommendation: When possible, I recommend choosing foods without added phosphate ingredients when you have chronic kidney disease.

How to Avoid Phosphate Additives 

When I work with someone who has CKD, one of my favorite things to teach is how to spot phosphate additives.

You don’t have to memorize every phosphate ingredient. I want you to start by looking for “PHOS” in the ingredient list.

Start with the foods you have all the time at home. If you find phosphates in your favorite food items, slowly replace them with brands that don’t have phosphates. 

My 10-Second Label Trick

I know ingredient lists can feel overwhelming.

Here’s the trick I use with my patients:

Flip the package over and look for “PHOS.”

If you see an ingredient containing “phos,” that’s a clue that phosphorus has been added.

They can look like any of these but are not limited to only these ingredients:

• Phosphoric acid
• Sodium phosphate
• Calcium phosphate
• Potassium phosphate
• Sodium polyphosphate

When possible, compare products and choose an option without added phosphate ingredients.

Some bottled iced teas, for example, may contain sodium polyphosphates and phosphoric acid. Formulations can vary by flavor and location, so always check the label on the specific product you are buying. (6)

Phosphorus Binders

If your blood phosphorus levels are high, your healthcare team may prescribe a phosphate binder. Phosphate binders work by attaching to phosphorus from the foods you eat while it is in your digestive tract. This helps keep some of that phosphorus from being absorbed into your bloodstream. (7) 

If you are prescribed a phosphate binder, it is important to take it with your meals and snacks, as directed. Taking it with food allows the medication to bind to the phosphorus as you digest your meals.

There are several types of phosphate binders, and the right one for you depends on your individual needs, medications, and lab results. 

Only take a phosphate binder if it has been prescribed by your healthcare team.

If you have questions about your phosphorus levels, your binder, or when to take it, talk with your healthcare team or renal dietitian. They can help you understand what is right for you.

What to Remember for Phosphorus in CKD

Phosphorus is an important mineral. Your body needs it!

If you have kidney disease, your kidneys may not be able to remove extra phosphorus as effectively.

That doesn’t mean you have to avoid every food that contains phosphorus.

Instead, I want you to focus on where your phosphorus is coming from.

Remember:

• Natural and added phosphorus are absorbed differently.
• Added phosphorus is absorbed very efficiently.
• Look for and avoid “phos” in ingredient lists.
• Your phosphorus recommendations should be individualized based on your labs, medications, kidney function, and overall health.

You don’t have to be perfect.

Start by making one change that feels realistic for you. Once you get comfortable recognizing added phosphorus and reading food labels, these choices can become easier over time.

What phosphorus change are you thinking about trying first? Share it in the comments!

This article was co-written by dietetic intern Keisha Kelly-Travis and reviewed, edited, and co-written by Candace Mooney, MS, RDN.