Matthew Mindler's Suicide Caused By Sodium Nitrate OD, Mom Speaks Out - TMZ

sodium nitrate is an oxidizing agent -- one often used to preserve foods, like meat -- that causes hypotension and limits the flow of oxygen in the body, which can result in death.

While sodium nitrate deaths are often accidental, Matt's was anything but ...

this according to his mom, Monica, who says she discovered a harrowing trail Matthew left behind.