Why is the RDA of Potassium so high?

I have done a little bit of googling and looking in nutrition textbooks, and I haven’t been able to find any sources that explain how the RDA of potassium got to be so much more than any person normally eats.

It’s something like 8 bananas.

The RDA implies that there would be some benefit to reaching that target, or some elevated risk in falling short of it. Does anybody know what research it was that led to the recommendation being where it is?


I have been wondering about this myself. The RDA seems like an absurdly high amount, or at least “high potassium” foods aren’t really high potassium.


Molasses has a lot of potassium, as do sweet potatoes and spinach. Good question, still. :stuck_out_tongue:

I’m interested as well. Oddly enough I just cut my potassium a couple days ago in my DIY. Today was the first day of the batch with half the potassium. I was going to be all science like, but forgot I had changed thing until I read this post. :smile:

It’s actually not something that will cause immediate illness, but chronic deficiency can cause trouble with your health, and amplify other illnesses. Potassium is involved in every cellular function, and is a critical component of all that your body does.

The question isn’t what happens when you don’t get enough, it is why the recommended amount is so high? It is hard to get those levels even with a high potassium diet, and if they are accurate then nearly everyone must be deficient.

Nearly everyone is deficient, and it results in higher rates of strokes, poor health, and so on. The RDA is so high because that’s what your body needs for optimal function.

There seems to be very little evidence of this in scientific literature?

Looks like they found a bare minimum. The justification occurs 3-5 pages onward, and papers are sprinkled throughout.

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So if 4.7g seems high, it’s partly because we need the extra potassium to offset all the extra sodium in the typical Western diet. A soylent-based diet with an appropriate amount of sodium should therefore require less potassium, perhaps.

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If you’re making the argument using this, can you summarize or give me a list of the relevant papers. I spent ~10min reading through but saw weak justifications and poor studies, but didn’t want to devote more time to making sure I was getting everything you were pointing at. So if you could just be more specific with what the actual justification is, it’d save both of us some time. :smile:

Give that the RDA represents an acceptable daily amount, and that excess potassium is trivially excreted if your kidneys are healthy, and my general trust that there would be a lot of conflicting and vociferous debate if the studies had a major flaw in credibility, I’m not really interested in digging in and tracking down all the papers. There appear to be a couple dozen throughout that paper. And yes, I know it’s flawed logic to trust that the lack of argument lends merit to a statement, but there’s a certain weight to it.

http://books.nap.edu/openbook.php?record_id=10925&page=193 has a list of studies,

That sounds reasonable, but the exact amount would require finding out the ratios, the mg/kg requirement for sodium, and learning any tertiary effects with other micros (like chloride, calcium, etc) and then lowering the amount.

I honestly think that a majority of the RDA’s overshoot the actual requirements by a safe margin, and that truly optimal nutrition will depend more on mg/kg ratios extracted from empirical data correlated to genetics, lifestyle, health condition, and so on.

For most intents and purposes, I’m happy with the RDAs, and I’m extremely happy with my current recipe. No muss, no fuss, generally ok on everything except chloride, and just 6 ingredients. It tastes great, too.

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I’m not disputing this. My comment was disputing the strength of evidence in scientific literature. In that context, I didn’t feel your reply was adding anything or touching upon my argument. As long as we agree on that, then there’s not much more to be said.

I will say that we are obviously coming from different places, and I absolutely respect your desire to give more weight to the ‘authorities’ than I obviously feel they deserve. Without revealing too much about myself, let’s say that I work with studies a lot, and most of the ones I see cited (especially if they’re prior to 1990) have shoddy methodology all around.

As mentioned, RDA for potassium has not been established yet, due to insufficient evidence, so 4.7 g/day is Adequate Intake (AI). They (Food and Nutrition Board of Institute of Medicine) establish these recommendations after decades of research about how the intake of a certain nutrient appears to prevent or promotes chronic diseases. At best, this is an estimation and not a hard claim, and it may change with time. This research often bases on “associations” between nutrients and diseases and not on the actual cause-effect relationships.

The other issue is that RDA and AI should suffice to ALL or MOST of individuals in a given age/sex group, including most active individuals who may consume 4,000 Calories per day or more. If you consume only 2,000 Calories per day, your personal requirement for a given nutrient will be much lower.

This is why FDA has established Daily Value (DV) for nutrients, which are often much lower than RDA, because they base on a 2,000 Calorie diet. DV for potassium is 3.6 g/day.

All these recommendations are explained here:

it would seem that the RDA of potassium should be a ratio rather than a set amount, a ratio between sodium and potassium


Yeah, I think the banana lobby started advertising them as “high potassium” although they aren’t especially. They’re a good source, along with a lot of other good sources that add up in a “balanced” diet.

Sweet potatoes, Irish potatoes (with skins), tomatoes, yogurt, beans, dried fruits, all potentially higher potassium per serving than a banana.

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I agree, a high potassium/sodium intake ratio may be more important than high potassium intake alone. Potassium can cancel some harmful effects of sodium, for example: sodium stimulates calcium excretion through urine, which increases the risk of kidney stones. Potassium, if excreted in urine in greater amounts than sodium, inhibits the sodium’s excreting effect on calcium. So, you can either increase the potassium or decrease sodium intake and you can achieve the same goal - less calcium excretion.


One consequnece of low potassium is if you don 't get enough you can have a heart attack. That is the worst danger. Potassium has a great deal of effect on muscles and the heart is a muscle. It is also an electrolyte, which means it has a part in almost every function of your body.

As for the salt/potassium relationship, it is if your body is lacking potassium, it goes into protective mode and that means trying to keep as much potassium as possible. When that happens it also retains salts, which in turn retains water. Those things are bad if you have high blood pressure. I can’t remember why the body also holds onto sodium when it tries to keep potassium, but it does. Perhaps it is that salts are excreted when you urinate and in retention mode, you are doing less of that.

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I don’t mean to split hairs, but RDA’s are not based on matching levels that are in existing diets. They are based on the levels we find necessary to avoid disease states. If studies find that we’re healthier if we consume more than the naturally occurring levels of something, then we’re healthier. “Natural” doesn’t always mean healthy… Like that naturally occurring cyanide in my kitchen in the seeds of my apples.

That being said, the potassium levels that are recommended are those which improve health, given a modern diet… And a modern diet has something like twenty times more salt, relative to potassium, than a primitive one… Both because we now add a lot of salt, and because we tend to eat less potassium. If we were consuming less salt, we might find we’d fare well on less potassium… But maybe not. Maybe some benefits of higher potassium would persist.

The best detailed, referenced write-up on potassium that I know of is here:

[Quote] Adequate Intake (AI)
In 2004, the Food and Nutrition Board of the Institute of Medicine established an adequate intake level (AI) for potassium based on intake levels that have been found to lower blood pressure, reduce salt sensitivity, and minimize the risk of kidney stones (4).[/quote]



I found this website that gives a ton of information on potassium and sodium and their subsequent relationship in our bodies. There are different articles with great info, look to the right of the page.