Kidney Diet Tips

Food Facts Friday: Tomatoes

Tomatoes are such a common staple in the typical American diet. They are so versatile and most people likely take for granted how often we enjoy this red round fruit. (Yes, it is a fruit!)

Salads often come with diced or sliced tomatoes. Don’t forget: ketchup is made from tomatoes as well. Sauce on pizza, lasagna and spaghetti is most commonly made from a tomato base. I live in Richmond, Virginia, and every year we celebrate the Hanover Tomato Festival because Hanover County grows amazing tomatoes.

Health Benefits

Tomatoes are generally known for being a good source of lycopene, which is an antioxidant. Lycopene has the potential to promote heart, eye and brain health (1).

Tomatoes also contain vitamin C, vitamin K and folate. There are many varieties of tomatoes and different uses for each (1). Let’s dive in and explore some different types of tomato.

Tomato Varieties

The red beefsteak tomato is good for salsas and for cutting a slice for a sandwich or a burger. Cherry and grape tomatoes are smaller and sweeter. They are good for roasting and can also be sliced in half for a salad. Roma tomatoes are good for roasting and adding to stews or sauces. Heirloom tomatoes are grown and passed down from generation to generation. They are typically a mix of colors or even a mix of color in the same tomato. This variety has a great flavor and are good for slicing or cutting up to top a crisp green salad (2).

Potassium in Tomatoes

People on a kidney diet may need to be cautious about eating tomatoes because of their potassium content. Potassium is an electrolyte that helps with muscle and nerve contractions, and keep in mind our heart is a muscle (3). If a person on dialysis takes in more potassium than the dialysis treatment can remove, it can affect how the heart beats, which can be dangerous. Let’s take a look at some different ways tomatoes are sold, their potassium content and the portion:

  • 1 cup crushed tomatoes: 709 mg potassium
  • 3-inch fresh whole tomato: 431 mg potassium
  • 1 cup canned tomato sauce: 727 mg potassium
  • 1 tablespoon tomato paste: 162 mg potassium
  • 1 cup tomato juice: 527 mg potassium
  • 2 tablespoons ketchup: 95 mg potassium

Ways to Keep Tomatoes in the Kidney Diet

A question many people on dialysis ask is, “Can I have tomatoes?” There are definitely ways to keep tomatoes in the diet when a person is on a low-potassium diet. A good place to start is to talk with your doctor about your blood potassium levels. You can work with your dietitian on ways to fit tomatoes into your diet. Here are some kidney-friendly portions:

  • 1 thick tomato slice: 64 mg potassium
  • 1 thin tomato slice: 36 mg potassium
  • 1/4 cup chopped tomato: 107 mg potassium
  • 3 cherry tomatoes: 120 mg potassium
  • 1/4 cup salsa: 176 mg potassium
  • 2 tablespoons salsa: 88 mg potassium

Recipes with Tomatoes has recipe ideas to help you keep the potassium level in your diet reasonable while still enjoying small amounts of tomatoes:

Portion and moderation are always key in keeping a food that is higher in potassium in your diet. 


  1. Healthline: Lycopene: Health Benefits and Top Food Sources (accessed April 15, 2021)
  2. NatureFresh Farms: The Tomato Lover’s Guide to Every Type of Tomato (accessed April 16, 2021)
  3. MedlinePlus: Potassium (accessed April 22, 2021)

Additional Kidney Diet Resources

Visit and explore these diet and nutrition resources:

This article is for informational purposes only and is not a substitute for medical advice or treatment. Consult your physician and dietitian regarding your specific diagnosis, treatment, diet and health questions.

Jackie Termont, RD

Jackie Termont, RD

Jackie has been a dietitian since 2007, and has been dedicated to renal nutrition since 2008. For two years she was the editor for the Renal Nutrition Forum, a publication for the Renal Practice group of the Academy of Nutrition and Dietetics. She enjoys baking, crafting, spending time with her sons and husband, and being active. She loves to experiment and come up with new recipes.