Potassium supplement causes heart failure in bodybuilder

Apparently harmless functional foods and supplements containing potassium can cause heart failure in healthy people, say doctors at the American Dartmouth-Hitchcock Medical Center. They saved a fanatical 35-year-old bodybuilder and a 65-year-old heart patient from death, in the nick of time.

Doctors advise people on medicines such as ACE inhibitors, anti-inflammatories such as ibuprofen, and diuretics such as spironolactone, not to eat too much potassium-rich food like bananas. The message in the American doctors' article is that there are products on the market that contain so much potassium that they can cause problems even if you don't take any of the above medicines.

The products the doctors are referring to are supplements that contain potassium gluconate [structural formula shown below], sports drinks that contain potassium compounds and low-sodium salt. These are all products that have been developed – ironically – to help restore balance in our diet. Manufactured food products contain more salt than is good for us, and our consumption of potassium-rich plant products is also rising.

The doctors describe the case of a 65-year-old man with atherosclerosis. Because his heart was having difficulty pumping enough blood around his body, he had switched to a low-sodium diet, and had started to use potassium salt instead. He shook eight tablespoons of the stuff over his meals every day, and on top of that he took potassium chloride as a medicine.

When he became short of breath and his muscles had stopped working properly, he admitted himself to hospital, where doctors normalised his potassium levels.

The second case that the doctors describe is that of a bodybuilder who was a fit as a fiddle. The man was admitted to hospital with heart failure: he had been unable to get up from the sofa he was sitting on. His blood pressure was very low and he was partially unconscious. The doctors revived him and got his heart going again. Then the first thing they did was to administer sodium carbonate and calcium chloride to reduce his potassium count; later they gave him insulin and glucose to counter the acidity in his muscles.

After three days the bodybuilder was discharged from hospital.

Eight grams a day of potassium is an extremely high, but not fatal, dose – if your kidneys are healthy and you are not on medication. Potassium only becomes fatal at 18 g a day – if you build up the dose gradually so your body can get used to it. If you don't give your body time to adjust…

"Our research revealed inadequate consumer warnings on these supplements", the doctors conclude. "We recommend clearer warnings."

Am J Emerg Med. 2011;29:1237.e1–1237.e2.