Sentence Correction

When would you use the phrase has been proven rather than has been proved. Case in point. In this official GMAT sentence, all of the answers have the phrase "has been proved," so the GMAT wasn't testing that. However, I thought that prove was an irregular verb, just like the verb to show.

I'm not disputing the GMAT, instead I'm wondering in what cases would you use proved rather than proven.

Although it has not been proved that the consumption of any particular food will reverse hardening of the arteries, studies indicate that refraining from eating certain foods can help reverse blockage of coronary arteries, the blood vessels that feed the heart.

"proved " and "proven" are both past participle of "prove."

So how do you know when to use which? Or are they completely interchangeable.

here is my take

Proven = usually used in descriptive form. Ex. "This is a proven formula." as an adjective since it modifies the formula

Proved = used as a verb. Ex. "He proved he was right."