The first GM product claimed to benefit consumer health was approved by the US Food and Drug Administration this week.

The genetically modified soya oil, which was produced by GM food giant Monsanto, contains omega-3 and would provide a cheaper and more plentiful source of the fatty acid for supplements, margarine and ready meals, said the company. "We can now open the door to a whole new way of delivering omega-3s in the diet through food," said chief technology officer Robb Fraley.

Previous GM products have provided higher yields or other economic benefits, but not health benefits.

The FDA's green light came ahead of expectations the oil was not expected to hit the market until the 2011-12 financial year.

There is less opposition to GM in the US than the UK. Major retailers here said they had no plans to introduce GM ranges in the near future.