taking potassium supplements without being monitored by a medical professional is not recommended. potassium supplements are known to cause bowel lesions, and if you don't have hypokalemia (low potassium in blood), taking extra potassium can give you hyperkalemia, which can cause serious heart arrhythmias. you probably don't have hypokalemia, its rare to get it from having too little potassium in your diet, so if you're taking a supplement without having seen a doctor about hypokalemia, you are genuinely at risk of hyperkalemia, excessive supplementation is a known cause of the condition.

to anybody reading, please don't take any supplements without talking to a doctor first. vitamin and mineral deficiencies can affect mood and general well being, but so can most medical conditions. unless you've taken a blood test, and are sure that the problems you're experiencing are because of a vitamin or mineral deficiency, taking supplements inappropriately can expose you to risks that are difficult to anticipate if you don't have a medical education.

If you find yourself just getting tired, anxious and racing heart from caffeine, that is a sign that you are deficient.

this is also not true. caffeine is a central nervous system stimulant. like other stimulants, it will increase your heart rate. feeling anxious when taking stimulants is a very common side effect. fatigue after caffeine wears off is also an extremely common side effect. the solution to feeling these kinds of side effects isn't to supplement an unrelated vitamin, it's to reduce your caffeine intake.