There's something about red. Studies suggest it makes women more attractive to men, and new research indicates red lipstick on waitresses is no exception.

A study in France found that red lipstick boosted female waitresses' tips from male customers, though not from female customers.

Researchers had seven waitresses wear red, pink, brown or no lipstick while serving 447 customers in three restaurants in the town of Vannes. In France, tipping is unusual because a 12 percent service charge is included in the price of the menu item.

The researchers, Nicolas Guéguen and Céline Jacob of the Université de Bretagne-Sud, found that male patrons gave tips more frequently to waitresses wearing red lipstick than to other waitresses, and, when they tipped, they gave more. This effect was found only for the red lipstick, not the other colors.

A waitress's lipstick or lack of it appeared to make no difference in how female patrons tipped.

Previous research showed men gave more tips to female waitresses wearing full facial makeup, but until now no study has looked at the effect of lip color alone, the researchers wrote online April 17 in the International Journal of Hospitality Management.

The "red effect" has shown up elsewhere. In prior research, women photographed against a red background were rated as more sexually attractive by men, but not by other women. Men found women in red clothes more attractive and even sat closer to a woman in a red shirt versus a blue one.

Crimson isn't just for the ladies, as research published in 2010 found that women from the United States, Germany and China found men wearing red to be more attractive and desirable than guys clad in other colors.

As for the appeal of red lipstick, others have suggested red lips could be associated with estrogen levels, sexual arousal and health.

"Such positive perceptions of the women could perhaps explain why men gave more tips to the waitresses wearing red lipstick in this experiment," wrote the French team.

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