+1 for potassium. Potassium, b1, manganese, vitamin A, zinc - they all help to rise potassium absorption. I proved it to myself with my experience. If your adrenals experience stress - there're million reasons (infection/insulin intolerance/lots of sugar/heavy metals/overworking physically and mentally/etc) they have difficult time retaining electrolytes (including potassium) in the body
Or it could be anemia - then iron, vitamin C and b vitamins (especially b6, folate, b12 and biotin) might be needed