Fewer than half of young UK adults know butter comes from a dairy cow and a third do not know eggs come from hens, according to a survey.
More than a third of 16 to 23-year-olds (36%) do not know bacon comes from pigs and four in 10 (40%) failed to link milk with an image of a dairy cow, with 7% linking it to wheat, the poll of 2,000 people for charity Leaf (Linking Environment and Farming) found.
Some 41% correctly linked butter to a dairy cow, with 8% linking it to beef cattle, while 67% were able to link eggs to an image of a hen but 11% thought they came from wheat or maize.
A total of 6% of those questioned knew that salad dressing could come from rapeseed oil, compared with the national average among all age groups of 24%.
Although four in 10 young adults (43%) considered themselves knowledgeable about where their food comes from, the results revealed a "shocking" lack of knowledge about how the most basic food is produced, the charity said.
Leaf chief executive Caroline Drummond said: "We often hear reports that our food knowledge may be declining but this new research shows how bad the situation is becoming.
"Despite what they think, young adults are clearly becoming removed from where their food comes from.
"Three in 10 adults born in the 1990s haven't visited a farm in more than 10 years, if at all, which is a real shame as our farmers not only play an important role in food production but are passionate about engaging and reconnecting consumers too."
The charity, which is organising an Open Farm Sunday event this weekend, also found almost two-thirds of young adults (64%) did not know that new potatoes would be available from British farms in June, and one in 10 (10%) thought they took less than a month to grow.
:: OnePoll surveyed 2,000 British adults online between May 11 and 14.
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