Scientists have created genetically modified cattle that produce human" milk in a bid to make cows' milk more nutritious. The scientists have ... introduced human genes into 300 dairy cows to produce milk with [some of] the same properties as human breast milk. The scientists behind the research ... hope genetically modified dairy products from herds of similar cows could be sold in supermarkets. The research has the backing of a major biotechnology company.Genetically modified food has become a highly controversial subject and currently they can only be sold in the UK and Europe if they have passed extensive safety testing. The consumer response to GM food has also been highly negative, resulting in many supermarkets seeking to source products that are GM free. Helen Wallace, director of biotechnology monitoring group GeneWatch UK, said: "We have major concerns about this research to genetically modify cows with human genes. There are major welfare issues with genetically modified animals as you get high numbers of still births. There is a question about whether milk from these cows is going to be safe for humans and it is really hard to tell that unless you do large clinical trials like you would a drug, so there will be uncertainty about whether it could be harmful to some people. Ethically there are issues about mass producing animals in this way."