That's funny you say that because I was curious to try the "flush version" of niacin today. Let me assure you, it is NOT good for anxiety. Luckily I enjoyed it the same way some might enjoy a roller coaster, but that's only because I knew to expect it. The person I was working with thought I was getting hives or something and I was tempted to pretend I was violently ill and go home, but I explained what it was from.
Magnesium according to many people is great for sleep, relaxation, calming the nerves, toning the nerves, leg cramps, etc. going back thousands of years. People used to and still do bathe in epsom salts. Essentially magnesium relaxes the bowels, but it also relaxes the rest of the body -- and I am about to test it out tonight. I am a VERY anxious typical hysterical female. So if it works on me, I'll shout it to the rooftops. I am trying the kind many have suggested, magnesium glycinate. I will also trial a few other kinds. It's such a basic thing, magnesium is, but if it works as well as some have claimed....well I'll eat my chapeau.
Definitely do not get the readily cheaply available magnesium citrate or oxide unless you really need to poop. When people say magnesium is good for cramps and muscle tension, they mean the other kinds -- glycinate being one. So there IS a difference and that's what going online is for, because a dumb doctor just told me, magnesium, without specifying. I have gotten better health advice from here or other sites than from any doctor, and that's just plain SAD.