Reheating Greens- A word of caution!

We are unable to keep many things in our mind due to the fast paced mechanical life.  There are many unfinished things at the end of the day!  It carries fwd for ever!  I made mustard greens yesterday and I knew it is good for you but out of curiousity went googling about its health and nutrition.  It is indeed a very good greens for people who do not have thyroid or stone related problems.  But while scrolling down, I read that we should not reheat any greens and not eat it after leaving overnight. 

Greens when cooked has nitrates in them, when you reheat, it becomes nitrites which is very poisonous. 

if you want to read more about it, here you go!

http://www.nutrition-and-you.com/mustard-greens.html

Disclaimer:  I found this info online and please verify it with your own resources.