Dear Doctor: I heard that getting more potassium will help with high blood pressure. Is that really true? I love salty food, and I really don't want to give up my chips and popcorn.
Dear Reader: The conversation about blood pressure focuses far more on salt -- or the sodium it contains -- than it does on potassium. That's because salt is so readily available. It's a potent flavor enhancer that finds its way into virtually all processed and prepared foods. This makes it easy to blow the daily sodium budget without adding even a grain of it yourself.
The maximum recommended amount of sodium for healthy adults is 2,300 milligrams per day. For certain groups, such as those with hypertension, diabetes, heart disease, chronic kidney disease and adults 51 or older, the maximum drops to no more than 1,500 milligrams per day. In reality, our average daily sodium intake is a whopping 3,746 milligrams per day.
Potassium recommendations are similarly ignored. The most recent research shows the average American adult consumes about 2,000 milligrams of potassium per day. That's less than half the recommended 4,700 milligrams per day. The result is most of us are not getting the ratio of potassium to sodium that the dietary guidelines recommend, which is twice as much potassium as sodium. In fact, studies show that sodium consumption often significantly outpaces potassium in the American diet.
This imbalance is a problem because sodium and potassium are inextricably linked. To understand why, we need to nerd out a bit. Potassium and sodium are electrolytes, which means they carry a tiny electrical charge. Our cells use this to create a molecular pump. When the pump brings potassium into a cell and pushes sodium out, it creates a kind of chemical battery. The output of these batteries plays a role in nerve function and muscle health, including the heart. Sodium and potassium are also vital to kidney function and bone health, and to blood and fluid balance, which helps regulate blood pressure.
When we overdo it with sodium, our bodies compensate by getting rid of it in urine. But this starts a cascade of events that lead to a loss of potassium and an influx of water, which results in a net increase in blood volume. Not only does that adversely affect blood pressure, the lack of potassium can cause electrical signals in the body to get disrupted. That interferes with the proper functioning of nerves and muscles, including the heart.
By following current United States dietary guidelines, we achieve the potassium-to-sodium ratio mentioned earlier, which is 2-to-1. Newer research leans toward ratios of 5-to-1 and higher. Unfortunately, most Americans miss even the more modest target by wide margins. Not only is that bad news for the vital functions we just discussed, but a new study published earlier this year also found that adults who took in more sodium than potassium increased their risk of stroke by 47 percent.
We understand your love of salt, but it's quite possible it has put you into potassium debt. Our advice is that not only should you make adding potassium-rich foods to your diet a priority, you should also reduce sodium. For a useful list of potassium-rich foods, visit health.gov/dietaryguidelines/dga2005/document/pdf/Appendix_B.pdf.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health. Send your questions to firstname.lastname@example.org, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.