I find that onions make me less constipated ! has anyone noticed the same?!

Are you eating that many onions that you can pin point them as the culprit?
I suppose they could but most people use 1 onion in a whole meals worth of food so an individual would actually get very little onion in each portion. A few shreds of something isn't enough to effect you one way or another unless you happened to be allergic and allergic reaction to foods is rarely stomach issue related.

Well, they have very very little fiber. However, they are mostly sugar. With sugar being a natural laxative perhaps that is why they fix you up.

Onions are only slightly laxative ...I doubt you would notice a difference..................

you can notice it on onion soup