The RenalTracker Team
June 7, 2020

I hope you enjoy reading this blog post. It has been written and vetted by RenalTracker's team of kidney experts and researchers. The same team was awarded the KidneyX Prize organized by the American Society of Nephrology and HHS for pre-dialysis solution in Washington DC in 2019.   

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Eating well when you have kidney disease can help you to stay healthy and strong. Daily consumption of the recommended kinds and amounts of food for a kidney diet can help your organs function more easily. This will also keep you well for a longer time.

Having Chronic Kidney Disease (CKD) can cause discomfort. Food can taste different and some people lose their appetite. When you have CKD, waste produced from the foods you consume builds up in the blood because the kidneys can no longer completely remove them. This can entail adjusting your meal plans depending on how well your kidneys are working. 

The Kidney Foundation of Canada suggests double boiling high-potassium tuberous vegetables or rooting vegetables like yams, potatoes, sweet potatoes, and others. The double boiling process is scientifically proven to remove potassium from these vegetables.

Eating these vegetables raw may not be advisable since uncooked and raw foods are linked to food-borne illnesses. The risk for food poisoning from raw foods is high for people with a weak immune system and those with chronic conditions such as kidney disease. 

Consult your doctor or dietitian on the amount and kinds of double-boiled high potassium root vegetables you can consume.

Kinds of Root Vegetables

  • Sweet potatoes and yams
  • Beets
  • Parsnips
  • Turnips
  • Rutabagas
  • Yuca root
  • Kohlrabi
  • Onion and garlic
  • Ginger
onion and garlic

Trivia: A 2018 psychological study revealed that “higher intakes of fruits and vegetables, rich in micronutrients, have been associated with better mental health. However, cooking or processing may reduce the availability of these important micronutrients.”

Important reminder: While double boiling vegetables is considered the best way to remove the most potassium from root vegetables, this process actually does not turn root vegetables into low-potassium food. It does, however, allow you to include these foods safely to your chronic kidney disease diet as long as it is in moderation.

So how to double boil vegetables?

The National Kidney Foundation of Canada gives us some useful instructions:

1. Wash and peel the vegetable.

2. Dice or thinly slice the vegetable.

3. Place the diced or sliced vegetable in room temperature water. Use two times the amount of water to the amount of vegetable.

4. Bring the water to a boil.

5. Drain off the water and add fresh, room temperature water. Use two times the amount of water to the amount of vegetable.

6. Bring the water to a boil again and cook until the vegetable is soft and tender.

Fact: Steaming vegetables helps to retain their flavor.

To give you more ideas, Food Revolution Network lists down foods that are more nutritious when cooked and foods that are more nutritious when eaten raw.

More Nutritious When Cooked

  • Spinach and other leafy greens
  • Asparagus
  • Mushrooms
  • Potatoes
  • Carrots, zucchini, celery, and green beans
  • Legumes

More Nutritious When Raw

  • Bell pep​​​​pers
  • Broccoli, cauliflower, and kale
  • Onions
  • Garlic

The Balancing Act 

Vegetables and fruits have a low content of calories, fat, and sodium. Depending on the recipe and meal plan, cooking can add fat, calories, sugar, and salt — but that isn’t necessarily a bad thing, especially when they are healthy fats, like those from olive oil and other plant-based oils.

So, which one is it — raw or cooked? 

Cooking actually destroys enzymes that help digestion. But cooked food, at the same time, is easier to chew and digest and as studies have suggested, increases some of the vegetables’ availability of antioxidants such as lutein (yes, the “eye vitamin”), beta-carotene (which helps us gain a healthy skin and immune system), and lycopene (which improves heart health and lowers the risk of certain types of cancer).

Trivia: There is more lycopene found in tomato paste and tomato sauce than in fresh tomatoes. Cooking allows the breaking of plant cell walls which means more nutrients available for consumption.

The consensus among most nutrition experts, according to the Food Revolution Network, is that we need both raw and cooked veggies to get the most food nutrients. The key is to be mindful of your nutritional requirements as a CKD patient. 


Potassium and chronic kidney disease | The Kidney Foundation of Canada 

Why Double Boiling Is Good For Your Health | Michelin Guide


Raw vs Cooked: The Healthiest Ways to Eat Your Veggies | Food Revolution Network 

Parenchyma cell microstructure and textural characteristics of raw and cooked potatoes |

Science Direct 

Lycopene is more bioavailable from tomato paste than fresh tomatoes | ResearchGate



Intake of Raw Fruits and Vegetables Is Associated With Better Mental Health Than Intake of

Processed Fruits and

Vegetables | ResearchGate

Is Raw Food Healthier Than Cooked Food? | Healthline

Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition |

International Journal of Food Science