Health juices touted as "a cure for everything" are being sold by Pacific Island churches in Christchurch and are worrying social workers and government officials.

Pacific Island Evaluation social workers were aware of one church minister who claimed his health juice could "heal illnesses" and had told a seriously ill man to drink it rather than take his prescribed medication.

Registered social worker and trauma counsellor To'alepai Louella Thomsen-Inder said the minister had described the juice as "a cure for everything".

"The minister claimed this magic water heals the soul and fixes everything, but the water is just water," she said.

This month, the minister doorknocked a churchgoer and enticed him into buying a $60 bottle of juice the day after he had been released from hospital with serious medical conditions, Thomsen-Inder told The Press.

The elderly Samoan man, who could not speak English, was told the drink would "heal his illnesses", but only if he stopped taking his antibiotics.

He bought the bottle, did not take his pills and ended up back in hospital with pneumonia days later.

Thomsen-Inder said the man was recovering at home and had since decided to "throw the magic water away".

She was concerned that several Pacific Island families, who look up to their ministers like "God", would buy the drink rather than go to the doctor.

"At the moment, Christchurch people are very vulnerable and they are reaching out for anything that is going. Any sense of hope and they try to grab it," she said.

A Pacific Island mother of two who attends a Hoon Hay church said her minister sold a health juice, but she had never bought a bottle because it was too expensive.

"He tells us it is good for him losing weight. It makes him healthy and helps for energy," Vaipa Isaako, 31, said.

However, the minister had had never told the congregation to buy the drink rather than take medication, she said.

The Press contacted Pacific Island ministers in Christchurch who were all aware of health juices being sold within the community, but they denied selling any.

One minister referred to the drinks as "medicine".

Tony Fakahau, a Christchurch Tongan community leader, was "not surprised" to hear churches had been selling health juices.

He had heard of "people linked to Tongan churches in Auckland" filling containers with water, adding a "natural ingredient" and selling it for $10 a bottle.

Fakahau recalled goji juice doing "the rounds through all Pacific Island churches" a few years ago and people claiming it cured cancer and diabetes.

Another natural health therapy used within the community's churches was the "salt detox foot massage", he said.

Churchgoers paid $30 each to put their feet in a bowl of salty water and, depending on which colour the water turned, sellers would advise them of their illnesses, he said.

"The best I can do is say to people, `Whatever it is you are doing, make sure you also do what the doctor says'."

Ministry of Pacific Island Affairs southern regional manager Amanaki Misa said health juices carrying "concerning claims" had been sold within New Zealand's Pacific Island community for years."Similar products have come up in the past, but those drinks should not substitute medication. Our message is consistent – go to your doctor," he said.

Canterbury District Health Board chief medical officer Nigel Millar said that people needed to talk to their GPs or specialists before trying alternative medications.