Are twisted spaghetti noodles always right handed?

While I was eating some spiral-shaped pasta noodles I discovered that all the noodles were right handed. The noodles were like the second set shown here. Are all spiral noodles right handed? If so, why?

(By “right-handed” I mean the spiral goes the same direction as a normal screw)

The Market Pantry (Target) brand rotini in our cabinet is “right hand thread.”

I’ve been told that these are produced with extrusion dies. That would make it very likely that all noodles from one company twist the same way. And it wouldn’t be too surprising if all companies conform to a right-hand rule.

It would, of course, be easy enough to do it the other way. Could you get consumers to pay enough attention that this would be a selling point? Doubtful, I’d say.

Especially since I would expect many pasta makers buy equipment from the same sources. In this case, seems like uniformity is just sort of the easiest way to do things.

There’s some left-handed pasta somewhere according to this account:

Maybe you could get ahold of Dr. Crespi and ask where he found it.

It happens because Italy and China, where noodles were first invented, are both north of the Equator. This is called the Raviolus effect.

South of the Equator, pasta turns the other way.

On the equator, you can only buy Penne.