When it comes to FD, I'd say the " proof is in the pudding" adage should apply.
Like most here, my early outdoor trip menus were freeze dried.
Mountain House I believe. That was 40 years ago and my age and the times didn't make/w about nutrition/sodium like they do now.

I knew they tasted saltier than my home meals, but like M_M, I figured I was sweating a lot of salt out, so a little extra shouldn't hurt.
Of course we now know that so many food stuffs contain hidden sodium, the average person even when under exertion doesn't really need anymore.

The biggest thing is how the FD effected my bowel habits :'(
I'm very regular in that regard and never have loose stools.
With freeze dried I wasn't always sure a gaseous event wouldn't turn into something worse ;D

I'm sure they've been improved over the years. I learned to de-hydrate make my own, so I haven't tried any since my early days.
I would say that if your experiencing gastronomic distress after every meal, then you need to find a different brand or start making your own.

If it's causing you daily distress, then it can't be good for you.
If health concerns are there, making your own lets you control whatever you need too. Worth the time and effort I would think.