Blog | Wednesday, May 20, 2009

Another reason to skip the soda: Potassium depletion

Supporters of the recent Senate Finance Committee proposal to tax sugary drinks may want to arm themselves with the findings of a new study on soda drinking. The study, published online May 13 by the International Journal of Clinical Practice, presents some alarming case studies of cola-induced hypokalaemia brought on by chronic consumption of up to 10 liters per day of sugar-sweetened cola.

The study's findings suggest that "potassium deletion should be added to the long list of soft drink-related health problems," (obesity, type 2 diabetes, dental decay and metabolic syndromes, to name a few), said a related editorial. To illustrate, the editorialist relates a case from his own files in which a 51-year-old man with COPD, hypertension and idiopathic gastroparesis developed persistent hypokalaemia, generalized weakness and loose stools. After running through a number of possible causes, the doctor hit upon the problem when the patient arrived in his office with a two-liter bottle of Pepsi in tow; upon further questioning, the patient estimated his total daily consumption at 4 liters. He agreed to keep his intake to two liters, and saw his potassium gradually rise back into the normal range.

The editorial also cites the intriguing case of a 44-year-old ostrich farmer who returned from a kangaroo-hunting trip in the Australian outback with profound muscle weakness and respiratory distress that required intubation and mechanical ventilation. It turned out that his serum potassium level plummeted when he upped his Coca-Cola intake to 10 liters (from his usual 4 liters daily) to combat his thirst on the hunt (From the study, "Coca Cola and kangaroos," Lancet, 2004; 364: 1190).

The editorial warns against relegating these cases as "outliers," citing some rather unsettling statistics. Worldwide consumption of soft drinks was almost 83 liters per person in 2007, with the U.S. level even higher at an estimated 212 liters per person. While healthy adults often can tolerate low potassium levels, not so for patients with heart problems, the editorial points out, and even moderate chronic cola consumption has been associated with chronic kidney disease.

The statistics should be a wake-up call for internists, especially considering the steady rise of obesity and type 2 diabetes. Most people know that sugary drinks are unhealthy, but public health initiatives have focused largely on children and teens. However, the editorialist urges, internists need to start asking their adult patients about soft drink consumption, along with questions about alcohol, cigarette and drug use.