How important is a low sodium diet for kidney disease?

This may or may not come as a surprise to you, but sodium has become a controversial subject in recent years. Our health agencies currently recommend that all people consume less than 2300 mg daily, but this is being called into question due to evidence that low sodium intake can also cause poor outcomes. Because of this, there are actually companies selling electrolyte supplements that contain large amounts of sodium…some even contain as much as 1000 mg! Yes, you read that right…not 100 mg but 1000 mg of sodium! Yikes!

If you have chronic kidney disease, however, do not be led astray by this talk.  It is very important for you to follow a low sodium diet! High sodium intake in people with CKD is associated with increased blood volume, blood pressure, faster CKD progression, increased cardiovascular events, increased proteinuria, and increased mortality.

What is sodium?

Sodium is a mineral and an essential electrolyte that your body needs to function properly. It plays a key role in maintaining fluid balance, nerve function, and muscle contraction. Sodium is naturally found in many foods, but it is most commonly consumed in the form of table salt (sodium chloride). Keep in mind it is an essential mineral…we’ll talk more about that later.

Why do I need a sodium restriction?

Sodium intake is a contributing factor to kidney function decline in CKD. Therefore, reducing sodium intake if your usual intake is too high can help slow kidney function decline.

Restricting sodium helps manage blood pressure, reduce fluid retention, and protect both kidney and heart health in people with CKD. It also helps reduce protein in the urine (proteinuria).

Eating at home most of the time, not cooking with salt, avoiding processed foods, and not using salt at the table, may be enough for most people. But if you’re looking for more specific guidance, read on.

What foods should I avoid?

Did you know that 70% of the sodium intake in the standard American diet (appropriately abbreviated SAD) is from restaurants and processed foods?

Some of the highest sources of sodium are bread, pizza, sandwiches, cold cuts, soups, burritos and tacos, savory snacks, and cheese.  Eliminating these foods from your diet will greatly help in preventing excess sodium intake.  

Eat at home!

One of the most impactful things you can do for your kidney health is to make the decision to cook your food from scratch and eat at home as often as possible.  That way, you can control the amount of sodium you’re eating.  The less sodium you eat, the more you will enjoy the actual flavor of your food.  Over time, you will begin to prefer that over the highly seasoned food you get from a restaurant. 

Read labels.

It’s important to read nutrition facts labels.  All Nutrition Facts labels are required to list the sodium content. Aim for 500-700 mg of sodium per meal and 100-150 mg per snack.

What else can I do to reduce my sodium intake?

Learn how to use herbs and spices in your cooking! There is a world of flavors out there just waiting to be explored!

Buy fresh meats without additives.  Stay away from sausage, bacon, ham, lunch meat, and meats that are already seasoned, such as those pre-seasoned pork tenderloins.  Look out for meats that have been injected with preservatives and flavor enhancers.

Buy fresh or frozen vegetables without sauces and season them yourself during the cooking process. If you do use canned vegetables, rinse them first to remove some of the excess sodium.

If you eat snacks, look for unsalted or low sodium varieties.  Remember to read labels. 

Choose light or low sodium condiments. This one is a little tricky because condiments that are labeled low sodium usually have the sodium chloride replaced with potassium chloride.  This is not a problem if your serum potassium is normal; but if it’s high, stay away from anything that has potassium chloride in it.

Reduce portion sizes of high sodium items. If you are in a situation that makes it difficult to avoid eating high sodium foods, just eat a small portion of it.  You can always eat something later that you know is better for you.  Remember  this: hunger is not an emergency.  In most cases, you can wait to eat your next meal. If you can’t, or if social obligations require you to eat at a particular time, just eat a small portion.

Make low sodium choices when you go out to eat. Almost everywhere you go out to eat, you can choose a lower sodium option.  You can also ask for your food to be prepared without added salt.

Other ways that sodium can impact health

Besides high blood pressure, which can result in kidney function decline, there are other ways that sodium intake can affect kidney health. One is proteinuria. Proteinuria is having high levels of protein in the urine.  

When proteinuria is present, some of the protein that should be in the body is filtered out by the kidneys, which can result in malnutrition.

Reduced sodium intake can make blood pressure medications more effective at reducing the protein in urine. 

If you are taking a medication categorized as an ACE or ARB, it is especially important for you to limit your sodium intake to prevent proteinuria. (ACE stands for Angiotensin-converting enzyme inhibitors and ARB stands for Angiotensin II Receptor Blockers.)

These include Benazepril (Lotensin®), Captopril (Capoten®), Enalapril (Vasotec®), Fosinopril, Lisinopril (Prinivil®, Zestril®), Moexipril, Perindopril (Aceon®), Quinapril (Accupril®), Ramipril (Altace®), Trandolapril (Mavik®), Candesartan (Atacand®), Eprosartan (Teveten®), Irbesartan (Avapro®), Losartan (Cozaar®), Olmesartan (Benicar®), Telmisartan (Micardis®), Valsartan (Diovan®)

Getting back to what I said previously about sodium being an essential mineral…it can be tempting to embrace a mindset that less is more.  You may think that if eating a low sodium diet is good, then eating as little sodium as possible is even better.  But your body needs sodium to perform basic bodily functions such as regulating blood pressure, fluid balance, nerve function, and muscle contraction. It also aids nutrient absorption and helps maintain the body’s acid-base balance. For this reason, some sodium intake is essential, and less is not more! Aim for a daily sodium intake of 1500-2300 mg per day.

References

Kang, M. (2021, February 20). Measured sodium excretion is associated with CKD progression: results from the KNOW-CKD study. Pubmed. https://pubmed.ncbi.nlm.nih.gov/32582942/

Navigating Sodium Intake in CKD: Essential Tips for Kidney and Cardiovascular Health. https://inkidney.com/sodium-intake-in-ckd/

Sodium in Your Diet Use the Nutrition Facts Label and Reduce Your Intake. https://www.fda.gov/food/nutrition-education-resources-materials/sodium-your-diet