Can changing to vegetarian diet delay or stop your period from coming?

I am usually every 28 days on the dot. I switched to vegetarian diet 3 months ago and HAVE had my period during it, but this time I am 3 days late. I have taken pregnancy tests and got negative results so the only thing I can think of is that maybe my body decided that since Im not giving it enough iron it isnt going to throw any away via menstruation....

Is that probably why I didn't get it?Can changing to vegetarian diet delay or stop your period from coming?
My gf Jenna says she is anemic and she sometimes doesn't get her period she is also a vegan so it means she is not getting enough iron and has to take iron pills. Also a change in diet may allow some weight loss this will also make a period late as well as stress or illness.