Potassium is a mineral that controls nerve and muscle function. It is a mineral found in many of the foods you eat. It plays a role in keeping your heartbeat regular. It is the work of kidneys to keep the right amount of potassium in your body.
The best potassium rich food sources must be high in potassium but low in sodium because sodium makes the body hold water. Natural plant foods are usually high sources of potassium compared to many processed foods. If your potassium becomes too high, it can cause an irregular heartbeat or a heart attack.
If there is potassium in the blood very low then it refers to the condition called Hypokalemia. Hypo means low, Kal means Kalium and emia means "in the blood."
You can know safe level of potassium in your blood by asking your doctor or dietitian about your monthly blood potassium level and check here:
3.5-5.0-You are in the SAFE zone
You can see here the list of Low and High fruits and vegetables: