Calculate Potassium Sodium Ratio

What is the potassium sodium ratio, and how do you calculate it? It is really quite simple. Add up the milligrams of potassium in the food that you eat in a day. Add up the milligrams of sodium in the food that you eat in a day. Divide the milligrams of potassium by the milligrams of sodium. The resulting number is the ratio. Most of the tables on this website have the potassium sodium ratio, in addition to amounts of potassium and sodium, for the most common foods. A list of tables with links to the tables can be found at the tab above labelled “Links To Food Potassium Tables.” Rather than calculate potassium sodium ratio, you can simply look it up.
Unequal Ratios

The Medical Literature Prefers Sodium Potassium Ratio

The confusion about the potassium sodium ratio comes mostly from the medical literature. The medical literature prefers using the inverse of the potassium sodium ratio – the sodium potassium ratio. To get this ratio, the amount of sodium is divided by the amount of potassium.

Two Versions Of Sodium Potassium Ratio

To add to the confusion, there are two common versions of the sodium potassium ratio used in the literature. One version uses milligrams of each substance. The other version uses millimoles or moles of each substance.

It is important to distinguish the specifics. If milligrams are used, simply divide the sodium potassium ratio into one to get the potassium sodium ratio. If moles or millimoles are used, divide the sodium potassium ratio into one and multiply by 1.7 (39/23, the atomic weights of potassium and sodium respectively).

The milligram version of the sodium potassium ratio is used in the literature most commonly when food frequency questionnaires are used to gather food information, or when food is measured in shorter studies. The molar version is used when estimates of consumption are made by collecting urine samples. Each of these methods has its advantages and disadvantages and can provide reasonable estimates.

Example Calculations

Here are some examples of how to convert the ratios commonly used in the medical literature. For an epidemiologic publication using participants on a typical American diet, a common sodium potassium ratio using milligrams of sodium and potassium in the diet is 1.67. This would translate to a potassium sodium ratio of 0.6 (i.e., 1/1.67).

For a publication trying to get more precise estimates of sodium and potassium by measuring the amount in the subjects' urine, a common sodium potassium ratio would be 2.7, since they typically use moles or millimoles of sodium and potassium. This would translate to a potassium sodium ratio of 0.63 ([1/2.7]*1.7).

In the posts on this site, we usually convert the numbers in a medical article to the potassium sodium ratio, and use milligrams. This makes it easier for you to compare to your own diet. When you are trying to figure out what foods to eat, use the milligrams in each food. The tables from the USDA give the values of potassium and sodium in milligrams. And the tables on this website use the USDA values, calculating the potassium sodium ratio from these values.

Institute Of Medicine Recommendation

The Institute of Medicine recommends obtaining 4700 mg of potassium and between 1500 and 2300 mg of sodium in a day if you are healthy. This lower sodium value should give you a ratio of greater than 3. For most people this should be a healthy ratio, and prevent hypertension and other associated diseases. There will be a few with unfavorable genetics who should get a higher ratio. The Institute of Medicine's recommendation for potassium is for those not having a restriction on potassium intake. If you have health problems requiring a restriction in potassium, the amount of potassium and sodium you take in should be directed by your doctor.

So for those of you who click on the links in the posts to the medical articles and get confused when you see different numbers for potassium, sodium, and ratios, I hope this clears things up a bit.