Too Much Potassium
Bananas are good for your heart in small doses. If you eat too many bananas, you can develop hyperkalemia. This means you have too much potassium in your blood.
Hyperkalemia can lead to irregular heartbeat, muscle weakness, and temporary paralysis. Most people won’t eat enough bananas to get to hyperkalemia. If you have kidney disease to other diseases that come with an elevated potassium blood level or you are taking potassium supplements, you may be at risk.