My husband just found out he has low potassium .what effect can this have on someone & will a banana now and then suffice, or are supplements? needed?

Low potassium: It depends how low is the potassium. Fruits and tomatoes are rich in potassium and they can help. If its very low, then prescription supplements can be used.

Low potassium levels: Hypokalemia (h) can be caused by many factors. It can be caused by urinary loses of potassium (k), due to diuretics or losses of k via the GI tract, diarrhea. Other causes of h are low levels of magnesium and primary aldosteronism. See the doctor who gave your husband the news of h and see if both of them can find the answer as to the cause of the h. Perhaps, a neprhologist be of help here.