It is Saturday morning in Sydney's inner-city and 29-year-old Julia Waring is about to start her family's weekly shop. Picking up a basket at the door of the organic store, she wanders through the vast warehouse-like space, where wooden crates of fresh food line the walls. She scoops up bundles of on-the-vine tomatoes and handfuls of luscious green beans.

Meanwhile, in Picton, on the outskirts of Sydney, Tatiyana Kuznetsov, 24, is also about to stock up at her local supermarket. She pushes a trolley through the labyrinthine aisles, throwing in packets of pre-packed vegetables, bags of oranges and loaves of multi-grain bread. Unlike Julia, Tatiyana won't feed her young daughter any organic produce, but there will still be plenty of fruit and vegetables in her fridge, and she'll have paid almost a third less. "Why would I bother with organic?" she asks, adding that it's more expensive and she's not "a health freak".

But when Julia and Tatiyana prepare dinner this evening, which woman will feed her family best? Is the organic food for which Julia pays top dollar really worth it? Or has she, and thousands of others like her, been sold a big, ripe, juicy lie?

Organic products have certainly become big business. These days, every fashionable suburb boasts a chi-chi organic store, complete with barista dispensing soy lattes in a corner, while organic skincare are the latest beauty buzzwords. In fact, Australian consumers now spend about $400 million on organic produce and Australian government websites show the industry is growing at a rate of 25 to 40 per cent every year. As niche markets go, this is a powerful one.

Every week, new studies are released espousing the value of eating organic. The claims seem logical and plausible: organic fruit and vegetables aren't sprayed with pesticides and are better for the environment; they contain more nutrients than their non-organic counterparts; they even taste better. "The biggest study into organic food has found it is more nutritious than ordinary produce and may help lengthen people's lives," claimed one story in The Australian newspaper last year.

But not every scientist advocates filling your basket with organic groceries. Trying to claim organic food is, on average, better is meaningless, according to Dr Peter Clifton, director of CSIRO's (Australia's Commonwealth and Scientific Research Organization) Nutrition Clinic and co-author of The Total Wellbeing Diet Book. "Short of testing every piece of food that you buy, you are never going to know."

In fact, some skeptics suspect there are other powers at play in the push towards organic products. A social conscience comes at a price - which means there's plenty of money to be made. Most organic products cost about 20 per cent more than their non-organic counterparts. Organic milk can cost around 30 per cent more, while some products (including cherry tomatoes) can be almost double. The latest figures from The Australian Bureau of Statistics suggest the average Australian monthly shop has increased by $139 in the last three years (thanks to a drought, rising global oil prices and increasing inflation). If families are feeling the pinch, they're far less likely to pay extra for organic produce.

Hear more on the organic debate in the October issue of marie claire