It’s the same reason why you should avoid eating avocados for kidney health: tomatoes contain a lot of potassium. Even though your body needs potassium for optimal function of your muscles, nerves, and heart, for those with chronic kidney disease, your kidneys don’t function as well as they’re supposed to. This means that they’re unable to remove excess potassium from your blood, which can lead to a buildup of the mineral in your system. This is called hyperkalemia, and it usually occurs in the later stages of kidney disease.
Too much potassium in your system can manifest as muscle weakness, numbness, and tingling, or it can be as severe as heart palpitations, difficulty breathing, chest pain, nausea, and vomiting, depending on just how much of the mineral is in your system. It can even lead to a heart attack.
For someone with chronic kidney disease, special attention is usually placed on potassium, sodium, and phosphorus levels. That being said, potassium becomes a concern with kidney impairment only if your doctor detects high potassium levels in your system. In other words, a low-potassium diet might not even be necessary for those in the first to third stages of chronic kidney disease. Dietitians often offer basic steps to follow when it comes to the consumption of tomatoes and other potassium-rich foods if you have kidney disease.