Whole Foods vs. Processed Foods

Published on: 06/25/2024

This is Part 1 of a 2-part blog explaining the benefits of a whole foods diet for people with chronic kidney disease.

Whole foods

In my work as a kidney nutrition specialist, I often talk with my clients about the importance of eating whole foods vs. processed foods, but I’ve found that many people don’t know what I mean by that.  For some people, it probably drums up a picture in their minds of a Whole Foods supermarket. For others, it may cause them to envision a side of beef.  Or a whole piece of fruit.  What is actually meant by the term “whole food” is foods that are minimally processed and as close to their natural state as possible. They are free from artificial additives, preservatives, and other synthetic substances. These include:

Fruits and Vegetables: Fresh, frozen, or dried without added sugars or preservatives.

Whole Grains: Such as brown rice, quinoa, oats, barley, and whole wheat products.

Nuts and Seeds: Unsalted and without added oils or sugars.

Legumes: Beans, lentils, and peas.

Animal Products: Unprocessed meats, poultry, fish, and dairy products without added hormones or antibiotics.

Healthy Fats: Such as those found in avocados, olive oil, and coconut oil.

Whole foods are rich in nutrient content, including vitamins, minerals, fiber, and phytonutrients, and their consumption leads to better health outcomes across the board.

Processed Foods

By contrast, processed foods are those that have been altered in some way from their original form, typically to enhance shelf life, flavor, or convenience. Processed foods are not so much a problem.  It’s ultra-processed foods that are more harmful.

Ultra-processed foods undergo extensive processing and contain numerous added ingredients, including artificial flavors, colors, emulsifiers, preservatives, and sweeteners. These foods are often designed to be hyper-palatable, meaning they are engineered to taste very appealing, which can lead to overconsumption. Ultra-processed foods typically have a much lower nutritional value compared to whole or minimally processed foods and can be high in unhealthy fats, sugars, and sodium.


  • Sugary cereals
  • Instant noodles
  • Packaged snack cakes and cookies
  • Soft drinks and energy drinks
  • Fast food items like burgers and fries
  • Pre-packaged frozen meals

Key Differences between processed and ultra-processed foods

  1. Ingredients: Ultra-processed foods contain many added ingredients and artificial additives, whereas processed foods have fewer and simpler additions.
  2. Nutritional Value: Processed foods retain more of their original nutritional content, while ultra-processed foods often have a lower nutritional value.
  3. Health Impact: Ultra-processed foods are more strongly associated with negative health outcomes, such as obesity, heart disease, and diabetes, due to their high content of unhealthy fats, sugars, and sodium.

Understanding the distinction between processed and ultra-processed foods can help you make more informed dietary choices, favoring whole and minimally processed foods for better health outcomes.

Why are whole foods important for people with CKD?

Consuming a diet high in ultra-processed foods subjects an individual to an increased intake of sodium and phosphorus, potentially thousands of food additives, and can entice that person to consume more food than their body needs, resulting in overweight or obesity.  Let’s take a look at each of these dietary mishaps and how they relate to CKD.


High sodium intake can significantly affect individuals with chronic kidney disease (CKD) in several detrimental ways. Here are the primary impacts:

1. Fluid Retention and Hypertension

  • Fluid Retention: High sodium intake can cause the body to retain excess fluid, which puts additional strain on the kidneys. This can lead to swelling (edema) in the legs, ankles, and face.
  • Hypertension: Sodium contributes to increased blood pressure by holding excess fluid in the body, which raises the volume of blood and consequently the pressure on blood vessel walls. Hypertension is a major risk factor for the progression of CKD and can further damage the kidneys.

2. Increased Proteinuria

  • Proteinuria: High sodium levels can exacerbate proteinuria, a condition where excess protein is found in the urine. This is a marker of kidney damage and can accelerate the decline in kidney function.

3. Cardiovascular Risk

  • Heart Disease: CKD patients already have an elevated risk of cardiovascular disease. High sodium intake increases this risk by contributing to high blood pressure and fluid overload, leading to conditions such as heart failure and stroke.

4. Impact on Kidney Function

  • Progression of CKD: Excessive sodium can worsen kidney function over time by increasing blood pressure and causing further damage to the glomeruli (the filtering units of the kidneys).

5. Bone Health

  • Calcium Loss: High sodium can cause the body to lose calcium in the urine, which can weaken bones and contribute to osteoporosis, a concern for CKD patients who are already at risk for bone disease.

Recommendations for Sodium Intake in CKD

  • Limit Sodium: Patients with CKD are typically advised to limit their sodium intake to less than 2,300 milligrams per day, and in some cases, as low as 1,500 milligrams per day, depending on the severity of their condition and medical advice.
  • Dietary Adjustments: This often involves reducing the intake of processed and packaged foods, which are high in sodium, and focusing on fresh, whole foods.


A 2023 study published in the Journal of Renal Nutrition found that of all the 3,466 U.S. packaged foods tested, over half contained phosphate additives. Phosphorus intake plays a critical role in managing chronic kidney disease (CKD). Here’s how phosphorus impacts CKD and the importance of managing its intake:

1. Phosphorus and CKD

  • Impaired Kidney Function: Healthy kidneys regulate phosphorus levels in the blood by excreting excess phosphorus. In CKD, the kidneys’ ability to excrete phosphorus is diminished, leading to elevated phosphorus levels in the blood (hyperphosphatemia).
  • Bone Health: Excess phosphorus can pull calcium from the bones, weakening them and increasing the risk of fractures. This condition is known as renal osteodystrophy, a type of bone disease common in CKD patients.
  • Vascular Calcification: High phosphorus levels can lead to calcification (hardening) of blood vessels, which increases the risk of cardiovascular disease, a major cause of mortality in CKD patients.

2. Consequences of High Phosphorus Levels

  • Secondary Hyperparathyroidism: High phosphorus levels stimulate the parathyroid glands to release more parathyroid hormone (PTH). This condition, known as secondary hyperparathyroidism, causes further calcium loss from bones and contributes to vascular calcification.
  • Increased Mortality: Elevated phosphorus levels are associated with higher mortality rates in CKD patients due to their effects on bone and cardiovascular health.

3. Managing Phosphorus Intake

  • Dietary Restrictions: Patients with CKD are often advised to limit their phosphorus intake. Past guidelines involved instructing patients to limit their intake of whole grains, beans, nuts, and other foods containing organic phosphorus.  In recent years, the guidelines have changed and patients are no generally no longer encouraged to limit foods containing organic, or natural, phosphorus.
  • Phosphorus Additives: Processed and packaged foods often contain phosphorus additives, which are highly absorbable and contribute significantly to phosphorus load. Reading food labels and avoiding these additives can help manage phosphorus intake.
  • Phosphate Binders: In addition to dietary restrictions, doctors may prescribe phosphate binders. These medications help prevent the absorption of phosphorus from the gut, thereby lowering blood phosphorus levels.

4. Recommended Phosphorus Levels

  • Blood Phosphorus Levels: It is generally recommended that blood phosphorus levels be maintained within the normal range (2.5 to 4.5 mg/dL). The exact target can vary depending on the stage of CKD and individual patient circumstances.

Practical Tips

  • Monitor Food Labels: Look for ingredients like “phosphate,” “phosphoric acid,” and “polyphosphate.” Identifying any ingredient with “phos” as a part of the name will help you avoid phosphate additives.
  • Consult a Dietitian: Working with a registered dietitian like me who specializes in chronic kidney disease can help tailor a diet that manages phosphorus intake effectively while meeting other nutritional needs.

Consuming a diet that contains mostly whole foods vs. ultra-processed foods is important for all of us, including people with CKD. We’ve just scratched the surface on the reasons for this, so stay tuned for more in the next blog post, Whole Foods vs. Processed Foods, Part 2.


Zhao, Flora. (2024, June 22). Widely Used and Deemed Safe, These Food Additives Are More Harmful Than Thought. Epoch Health. https://www.theepochtimes.com/health/widely-used-and-deemed-safe-these-food-additives-are-more-harmful-than-thought-5654808?src_src=Goodevening&src_cmp=gv-2024-06-23&est=AAAAAAAAAAAAAAAAc%2B0pdxoJyM%2FM5LYPqm1cGadazE4PLiVA1sxgFyRxNuzNdYRp2juZTGJuVA%3D%3D.

Picard, Kelly. (2023, May). Phosphorus Additives and Their Impact on Phosphorus Content in Foods-An Analysis of the USDAs Branded Foods Product Database. PubMed. https://pubmed.ncbi.nlm.nih.gov/36731685/

Want to know more about whole foods and CKd?

If you have a desire to learn more about eating a whole foods diet for CKD, download my free Ebook

“The #1 Most Important Change you can Make for CKD”.


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Meet Heather
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Although I’ve been a dietitian for more than 20 years, it’s the past few years that have convinced me to take control of my own health by changing the way I eat. So many chronic illnesses can be corrected or prevented through good nutrition. I am thankful to have the opportunity to walk with people in my community, Beaufort, SC and beyond, through their own journeys as they reclaim their health.

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