Health-conscious shoppers are being duped into buying products labelled "organic" without knowing what it means or if the product is what the label says it is, experts warn.
A study at New York's Cornell University found people believed food labelled "organic" tasted better, was lower in calories and was better value than other food.
New Zealand has no regulations stopping food producers using the word "organic" on their products.
The Commerce Commission says suppliers or growers can label their produce as organic even if they have not been independently certified as organic producers.
Otago University food scientist Dr Miranda Mirosa said labelling was a powerful tool in selling organic products and could easily affect buyers' perceptions.
"There needs to be tighter controls on food labelling because consumers are very vulnerable to what they see in the shops," she said.
"I've found that the labelling system at the moment is not clear because not all organic food is certified, so sometimes you just have no idea what you're buying.
"Words like 'natural' and 'free range' are used, and sometimes not appropriately.
"Shoppers will sometimes be persuaded by a pretty picture of a large green field, and can get the wrong idea about how the item has been produced."
Consumer behaviour expert Bodo Lang of Auckland University said health-conscious shoppers often fell for the "organic" label.
Organic labelling added a huge amount of value to the brand.
The Cornell University study findings were consistent with previous marketing research which showed consumer perception was heavily influenced by brand names and labels, Dr Lang said.
The general manager for organic food supplier Huckleberry Farms, Dave Spalter, agreed tighter restrictions were needed.
"We often have to act like the police and check out places that might supply us with products. It's a big part of our job; there aren't enough restrictions," he said.
"In my opinion if the word 'organic' is on the label then it should be certified, no two ways about it."
Producers "need to be able to prove it", he said.
"Labelling is such a powerful tool for customers and people can be duped if they're not a dedicated organic produce customer who knows what they're looking for."
Shopper Sue Matson, 46, said she bought organic food if it was convenient for her to do so.
"It tastes better - definitely vegetables," she said.
Jennifer Harris, 53, grows her own vegetables.
"I would probably always buy organic if I knew it was organic ... and not just a marketing ploy."
Price and appearance of items were also important.
Janet Lucena, 74, bought organic food as often as possible.
"I think it does taste better but I don't think it's any better for you."