A Chicago researcher has said that the smell of grapefruit can make women appear to men to be almost five years younger than they actually are.
But, in a study conducted by Dr. Alan Hirsh, for men, the aroma of citrus didn't have the same effect on women's perception of them. There was also no difference found in the way women see other women.

"That suggests either that men are more easily influenced by a woman's aroma or that women are so adroit at estimating age that nothing will impact them," stated Hirsh, who is a neurologist and psychiatrist and also the director of the Smell and Taste Treatment and Research Foundation.Other smells seem to affect different people in different ways. For example, combining lavender and pumpkin pie works for male sexual arousal, while combining cucumber and Good & Plenty works for women.

Hirsh has also conducted several studies that show hoe aromas can affect everything from human sexual response to diet. He feels that smells are so powerful because they travel a pathway that goes directly to the emotional part of the brain.
"It's the quickest was to have an impact upon one's innermost behavior," he said. "You smell a smell and you immediately like it or you don't, and you figure out why later."Hirsch is still unsure why grapefruit distorts a man's ability to estimate the age of a woman, but he speculates the aroma may lead to a heightened well being that leads to a more 'optimistic' view of the physical attributes of the women around them.