Shoppers who buy their fruit and vegetables from markets get better value for money and access to "affordable, fresh food" than those who go to supermarkets, according to research.
A survey of markets in London found that fresh produce can be up to a third cheaper than at local supermarkets.
The research, for the Mayor's London Food board, found that street markets in the capital were significantly cheaper than neighbouring supermarkets, while farmers' markets offered fresher, more locally sourced food than many supermarkets and were competitive on price.
The markets also improved custom for local shops, including grocery stores, and could boost local employment.
The research found that most shoppers who bought their food at farmers' markets did so "because of the quality and a desire to support farmers". But it also found that farmers' markets, where growers and small traders bring their produce into London for sale once a week, were competing with supermarkets on price.
A basket of goods at Marylebone farmers' market cost £7.90, compared with £8.90 at a local supermarket, while in Ealing the farmers'-market basket cost £6.90, compared with £5.81.
"Farmers' markets are also more price competitive than is often presumed, and as the price analysis demonstrates can compete effectively with supermarkets," says the report, Trading Places. "Both street markets and farmers' markets provide destinations for customers and encourage people to shop in the areas in which they are based."
The report, funded by the London Development Agency, found that at Lewisham street market produce was 34 per cent cheaper than at the local supermarket; at Walthamstow market it was 29 per cent cheaper.
Jenny Jones, a Green Party member of the London Assembly and chair of London Food, said: "As well as the good value and freshness of the produce, people go to street and farmers' markets because they have interaction with people that you don't get in supermarkets. They like the social contact."
Farmers' markets, which often stock organic produce, are growing in popularity among Londoners. But the survey found that despite their positive impact on local economies, street markets are struggling.
"Prices at farmers' markets can be either greater or less than supermarket prices, but the difference is relatively small," the report said.