Mushrooms have no nutritional value

[snopes]

Comment: I keep hearing from various people that mushrooms have no
nutritional value. The idea is that mushrooms are "nature's styrofoam" or
something similar.

When I do a bit of back research, I get the same list of minerals
[selenium, potassium, phosophorous] from every source. Some sources add
proteins and fibres to the list, and some add fibres but comment that
mushrooms are indigestible, which might be why I've been hearing they've
got no nutritional value.

Unfortunately I haven't received any claims of mushrooms having no
nutrients via writing, so I have nothing to pass on.

[Squishy0405]

I did a quick search for "Calories in Mushrooms" b/c I thought it would prove to have better results. I found this site about "raw" mushrooms being particularly healthy. Now maybe, after cooking, as some veggies do, the nutritional value goes down.

[Joostik]

Generally speaking, because of their cell structure, mushrooms are rather hard to digest (which means you have to prepare and chew them properly). Nutritional value can be fairly high but differs widely among species.

[Floater]

It's not about the nutritional value but the energy content. At survival courses people are told not to pick mushrooms because the energy it takes searching for them exceeds the energy they can give you by a wide margin.

[Joostik]

Originally Posted by Floater

It's not about the nutritional value but the energy content. At survival courses people are told not to pick mushrooms because the energy it takes searching for them exceeds the energy they can give you by a wide margin.

Depends on where and when. If you go out specifically to search for mushrooms and nothing else, then, yes, in most cases you would just get hungry. But what if, when doing other things, you chance upon an abundance of mushrooms which just happen to be in season?

OTOH if I gave survival courses, I'd probably tell them the same thing. Better be safe: especially when hungry people might pick the wrong sorts or, even more likely, not-quite-fresh specimens.