How much potassium would you expect from a supplement called "Potassium Gluconate 595 mg"? The correct answer is just 99 mg, as ConsumerLab.com explains in its new Potassium Supplements Review, published online. While potassium labels may be confusing to consumers, the good news is that ConsumerLab.com found the quality of supplements to be high across the products it selected for testing. ConsumerLab.com also found that you could spend as little as one cent to get a 99 mg dose of high-quality potassium, rather than spending many times that amount.

Potassium supplements are used to treat or prevent potassium deficiency and are commonly taken by people on certain diuretic antihypertensive drugs which cause potassium loss. Potassium deficiency can cause muscle weakness, irregular heartbeat, listlessness, mood change, nausea, and vomiting. Potassium supplementation may also help lower blood pressure in people who consume high amounts of sodium. Sales of potassium supplements in the U.S. were estimated at $95 million in 2012 according to Nutrition Business Journal.

ConsumerLab.com tested supplements to determine if they contained their listed amounts of potassium; did not exceed contamination limits for lead; and, if pills, would properly break apart. All products passed these tests. However, it found brands differed on how labels portrayed the amount of potassium in the products. Potassium is chemically unstable and, therefore, is always bound to compounds which stabilize it. Potassium makes up far less than half of the weight of most of these potassium compounds, accounting for only 16.7 percent of the weight of potassium gluconate, 38.3 percent of potassium citrate and 52 percent of potassium chloride. Consequently, a product named "Potassium Gluconate 595 mg" will actually contain only about 99 mg of active "elemental" potassium. This important fact may be missed by many consumers when only disclosed in the Supplement Facts panel on the back of the bottle.

"We are glad that the findings for this group of potassium products were positive, but consumers should be aware that this is not always the case. In addition, they must carefully read the Supplement Facts panel on labels to be sure they are choosing a product with the right dose of potassium," said Tod Cooperman, M.D., ConsumerLab.com president.

ConsumerLab.com's Potassium Supplements Review is available at consumerlab.com/reviews/Potassium_Supplements/Potassium. It includes quality ratings, price comparisons, and ingredient comparisons for seven products selected, tested, and rated by ConsumerLab.com as well as for eight that passed ConsumerLab.com's Quality Certification Program. Also listed are two products similar to one that passed testing. Potassium supplement products included in the report are 21st Century Potassium Gluconate 595 mg, CVS/pharmacy Potassium Gluconate 595 mg, Douglas Laboratories Potassium 99 mg Chelated, Finest Nutrition Potassium Gluconate, KAL Potassium 99 Chloride, Natural Factors Potassium Citrate 99 mg, Nature Made Potassium Gluconate, Nature's Bounty Potassium Gluconate 595 mg, NOW Potassium Chloride Powder, Puritan's Pride Potassium, Simply Right Potassium Gluconate 595 mg, Solgar Potassium, Sundown Naturals Potassium Gluconate 595 mg, Thorne Research Potassium-Magnesium Citrate, Twinlab Potassium Caps, The Vitamin Shoppe Potassium Citrate, and Vitamin World Potassium 99 mg.

The report also provides information about the forms of potassium, dosage for specific uses, concerns and cautions with potassium supplement use, and additional clinical information.