Health-conscious millennials show the greatest preference for organic food, while 18 per cent of regular organic food buyers say their switch was triggered by a personal or family health crisis.

A new report to be released ­tomorrow by the Australian ­Organic organisation estimates the organic industry will be worth nearly $2 billion a year by 2018, with retailers and farmers struggling to meet demand.

Fruit and vegetables are the No 1 organic food for Australian ­buyers, while demand for organic eggs grows 10 per cent a year and organic dairy and red meat ­demand rises 6 per cent annually.

Organic vegetable grower Wayne Shields knows first-hand just how quickly demand is mushrooming and the sector booming.

Seven years ago he switched to small-scale organic vegetable farming at Baxter on Melbourne’s Mornington Peninsula after losing a NSW farm business because of chemical spray contamination.

What started as a 2ha organic plot to supply the Red Hill Farmers Market with carrots and ­lettuces, has grown into two properties and his well-known Peninsula Fresh Organics business. Mr Shields grows organic leafy greens such as kale, spinach and lettuces, alongside broccoli, spring onions, leaks, carrots, ­melons and brussels sprouts ­almost all year round, supplying wholesalers, supermarkets and specialist food stores in Victoria, NSW and Queensland, as well as six local farmers’ markets.

As the Australian Organic report found, exporters are also seeking out Mr Shield’s organic vegetables, with large quantities of his fresh kale, celery and leeks now flying out every week from Melbourne Airport to Singapore and Dubai. “It’s one of those things I am continuously surprised by; the demand is there, I keep growing more and people still can’t seem to get enough of it,” said Mr Shields yesterday, harvesting organic lettuces on his Barham farm irrigated from the nearby Murray River.

“I’ve expanded and the opportunities to sell to more wholesalers and now to export more just keep coming from all directions; it’s turning into a bit of a monster.’’ Young millennials were the keenest shoppers, with 20 per cent of their organic food bought at specialist “natural outlets” and with the Australian Organic certification logo the most recognised proof of its organic credentials.

Supermarkets remain the dominant retail outlet with their organic businesses expanding. Woolworths last year reported a $60 million jump in its organic produce sales. The Australian Organic report also found that Australia now has the largest certified organic land mass in the world ? a vast 27 million hectares or 53 per cent of the world’s certified organic farmland.