Organic produce makes up 1.5% of food sales
The report by consumer analysts Minitel points to new scepticism about the organic market, despite the surge in sales.
Purchases of organic foods have soared in recent years and are predicted to be worth more than a billion pounds by the end of the year.
But Minitel says shoppers are beginning to question whether organic food really is better for you.
'Questioning'
Industry figures show the market for organic food and drink has grown by 35% in the past year and is now worth £980m.
Even so the sector is only estimated to account for around 1.5% of all food and drink bought in the shops.
The report suggests a drop over the last two years in the number of people thinking organic products are better for you than non-organic.
The BBC's consumer affairs correspondent Nicola Carslaw said: "People are more questioning about whether organic produce really is the solution to their concerns in the wake of BSE and other food scares and whether organic food even tastes better."
In 1999, 22% of people questioned in the UK said organic was safer, falling to 16% last year.
'Peaked'
The research also indicated a decline in the belief that it is better for you, down from 22% two years ago to 18% in 2001.
Minitel's survey involved 1,000 adults who were questioned about their thoughts on organic produce.
Young people were said to be among the most sceptical with just 11% of 15 to 24-year-old's surveyed last year believing organic produce is better for you than ordinary food.
This compared with 20% in 1999.
James McCoy, senior consultant analyst at Minitel, said: "Research suggests that the proportion of active buyers of organics has peaked, which may well slow the current rates of growth."
While enthusiasm for organic food is said to be declining in the UK, consumers in Scotland appear to be bucking the trend.
Scots consumers are reported to be most likely to believe in its health benefits.
Almost one quarter of people north of the border thought organic food was safer than non-organic.
In contrast, just 10% of those living in London thought the same.
While organic food is likely to remain popular, Minitel believes in the future it will be bought by a core number of consumers opposed to over-production and the use of pesticides.