Another man, aged 68, remains in hospital in a critical condition.
The group had dined together at a house in the small town of Leongatha last weekend, and afterwards contacted doctors with concerns they had gastroenteritis.
South Gippsland Shire Mayor Nathan Hersey told the Age newspaper the men and women were “very well-respected” and connected to the local Baptist church.
“The council is aware [of the poisoning] and has reached out to the family, but at this stage, they’ve said they’re well-supported, being well-cared for and have asked for privacy,” Hersey said.
Leading Senior-Constable Kendra Jackson, from Victoria Police, said: “The investigation surrounding the exact circumstances of the incident remains ongoing, and police are liaising with the Department of Health in relation to the matter.”