Zonfrillo, who died in Melbourne on Sunday, kept his health problems quiet and usually received treatment when the hit Network Ten program was not filming, sources have said.
The Glasgow-born father-of-four credited his mentor Marco Pierre White with saving his life after giving him a job and accommodation when he was a homeless heroin addict.
Life as he knew it imploded one day in 2014, when he fielded a call from a journalist who told him he was about to run an Australian exclusive story about his addiction.
Jock Zonfrillo secretly battled bowel cancer for years. He kept his health problems quiet and received treatment when he was not filming. It is not suggested the 46-year-old died of cancer.