What Is a Potassium Chloride Powder Supplement? A potassium chloride powder supplement contains a potassium salt powder thatacts as a source of potassium. Potassium chloride is often mixed with table salt to form a low-sodium salt alternative. Potassium is an essential nutrient that is important in maintaining hydration in the body. Potassium is found in many fruits and vegetables most famously bananas. Please be aware that serving sizes listed on our website are subject to occasional adjustments based on factors such as variations in ingredient availability and supplier changes. Potassium Chloride Powder Supplement Benefits* Potassium chloride powder supplements may support healthy nervous function, the muscles, and heart function. Potassium is also an important electrolyte that assists in maintaining hydration of the body.