It was already known that eating extreme amounts of certain vegetables such as carrots could turn skin orange. However, it was not known that a small increase in these red and yellow pigments in the skin could be perceptible to others - or that it was seen as appealing.
A camera which can measure close-up changes to the skin's redness, yellowness and lightness found that this significantly increased in people who increased their intake of fruit and vegetables.
Using light sensors, the researchers showed these red and yellow hues were linked with the levels of carotenoids in the skin.
There are hundreds of different types of carotenoids.
But those thought to have the most dramatic impact on the skin are lycopene - which gives tomatoes and red peppers their red colour - and beta-carotene, found in carrots as well as broccoli, squash, and spinach.
Skin colour can also be affected by chemicals called polyphenols, found in apples, blueberries and cherries, which cause blood rush to the skin surface.
Ross Whitehead, who lead the study published in the journal PLoS ONE, said: 'We expected the colour change to be most dramatic in people who ate very few fruit and vegetables to start off with, but it was actually across the board.
"A lot of the people were already eating close to the recommended amount.
"But we found even a couple of extra portions could still make a difference to their skin colour."
He said the team, who studied white and Asian volunteers, would look at whether this was also true for other races, and whether it had a smaller or greater effect in older people, as the volunteers were all aged 18 to 25.