I decided to look up the nutritional properties of the grapefruit I was eating, and found this bit rather interesting:
Grapefruit contains large quantities of a simple polyamine called spermidine, which may be related to aging. It is known to be necessary for cell growth and maturation, and as cells age their level of spermidine is known to fall. Scientists have shown that feeding spermidine to worms, fruit flies and yeast significantly prolongs their lifespan. In addition, adding spermidine to the diet of mice decreased molecular markers of aging, and when human immune cells were cultured in a medium containing spermidine, they also lived longer.
The cited reference goes to this article, in which the researcher states:
Humans are exposed to spermidine in quite high concentrations during sexual intercourse. Also grapefruit contains high concentrations, so natural sources are available. People could try to stay young by eating a lot of grapefruit and having a lot of sex – it might not work but I don’t think it would do much harm.
My preferred method (for eating grapefruit, of course), is to make two shallow, perpendicular, longitudinal cuts to make it easier to peel. Once peeled, I pry it roughly in half, then use the knife to cut the sections apart, and cut those sections into thirds. I put all the chunks into a bowl and eat them with a fork. Delish!