Ask A Dietitian Q and A: Tomatoes

Tomatoes are one of the foods that kidney dietitians get asked the most about. They are a high potassium food but does that mean everyone with kidney disease has to completely avoid them forever? We aim to dispel some myths and provide some facts about eating tomatoes as part of a kidney-friendly diet.


I’m newly diagnosed with chronic kidney disease (CKD) Stage 3, can I eat tomatoes?

It is extremely rare for people with CKD Stage 3 to need a low potassium diet. Potassium levels in the blood commonly start to increase at CKD Stage 4 and above. If you have CKD Stage 3 then one of the most important things you can do is to eat a healthy balanced diet with a variety of fruit and veggies, including tomatoes!  If you have not been advised that you need a low potassium diet, then there is absolutely no need for you to stop eating tomatoes.


What’s an alternative snack to cherry tomatoes if you’re on a low potassium diet and have diabetes?

We’ve seen many people with diabetes and chronic kidney disease ask us for help with their eating as balancing both diets is demanding. And finding different healthy snacks is often a big challenge. Does this sound like you? Firstly, cherry tomatoes do not need to be completely avoided. A couple as part of a snack is likely to be fine. But you can also swap them for some lower potassium alternatives such as raw carrots, sliced mixed peppers, cucumber batons or celery sticks. You can make your own yummy no salt herby yoghurt dip to accompany it.


We use tomato paste in our curries. Help! What shall we do?

It’s a very concentrated source of tomato which makes it extremely high in potassium. If you have been asked to follow a low potassium diet, a compromise would be to use a small amount of fresh or chopped tomatoes. An ideal portion would be 2 medium tomatoes or a tin of chopped tomatoes for 4 servings. Limit the use of other high potassium vegetables and potatoes in your curry too. Serving with a low potassium staple food such as rice will balance the overall potassium content of your entire meal.


Can I use jars of tomato sauces for my pasta dishes?

Ready-made pasta sauces are often a staple cupboard item in many kitchens. They are cheap, versatile and a great time saver. But they are usually loaded with salt and sugar and are not recommended for anyone on a low potassium diet unless you use a tiny amount. So what can you do instead? Make your own pasta sauce! All you need is a standard-size tin of chopped tomatoes, onion, garlic, olive oil, dried oregano and black pepper for your own quick homemade sauce. But remember, quantity is also important so this should provide no less than 4 servings.


Do I have to remove tomatoes from my lunchtime sandwiches?

No foods are ever completely banned on a low potassium diet. Not even tomatoes. That’s right! The key is moderation and only having foods that are high in potassium in very small quantities and infrequently. A few thin slices of tomatoes in your lunchtime sandwich is unlikely to do any harm but try to avoid having them every day. But why not substitute for other raw lower potassium alternatives on some days such as cucumber, grated carrot, sliced mixed peppers, lettuce, sliced onions or rocket.

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