And yes it is. And that's a concern when eating the standard American diet, which consists of high amounts of sodium without also providing much in the way of potassium. So, when eating the SAD diet, it's a good idea to read nutrition labels and keep the number of milligrams of sodium intake at equal to or under the number of calories being consumed. In other words, if a product is 100 calories per serving, then ideally the number of milligrams of sodium should be 100 mg or fewer.
But blood pressure isn't controlled by sodium alone. There's an interplay between sodium, potassium and calcium and ideal blood pressure is affected by that interplay. Whereas sodium increases blood pressure, potassium lowers blood pressure. And while the standard American diet is high in sodium in comparison to potassium, and therefore can be detrimental to our blood pressure, that's not the case with miso.
Miso is high in both sodium and in potassium. And what's the end result of that? I'll let a study published in September 2012 in the journal Nutrition speak to that. In that study, miso soup consumption was found to have a beneficial effect on blood pressure. Not only did long-term miso soup consumption prevent high blood pressure, despite its high sodium content, but it was also found to increase the amount of sodium that the body excreted while at the same time guarding against potassium loss. In other words, miso soup actually helped the body retain potassium and get rid of excess sodium. And that means not all the sodium is even absorbed by the body.
While not speaking specifically to this interaction, Dr. T. Colin Campbell in his book Whole does speak of "the complexity of nutrient interactions" and the "pointlessness of reductionist precision." On page 70, he does link the interactions of potassium, calcium and sodium as well as others in playing a role in our health. It's not one mineral like sodium that adversely affects us. It's only when we take that one mineral and make it a large part of our diet, such as what the standard American diet does, that makes it a problem.
Miso is not part of the standard American diet though, and so the sodium content of miso should not be judged in that context. While this is anecdotal, many people in our club who have tried miso have been pleasantly surprised to find that their blood pressure did not go up and in some cases it went down. I believe that's because the sodium was balanced or offset by the potassium in the miso and in the kinds of vegetables, such as wakame that get put into dishes like miso soup. And I believe there is research to back that up.
So, in answer to all the questions I've received since my miso posting, I wanted to do this followup posting to explain why I am not particularly concerned about the sodium content in miso.