Offer him a cup of coffee each day. Research in the United States indicates that men who drink coffee regularly have better erections. In effect, caffeine is a powerful stimulant of the nervous system and a [word-i-don't-know]-muscle relaxant (these muscles are indispensable to erections).
Boy, if it is true, I am in good shape. But who knows. The whole article is filled with vagaries about studies showing that 90% of so and so's who this or that are more likely to blabidee blah.
My favorite citation (so to speak) is the "research in the United States", as if the U.S. is some exotic land of scientists. It reminds me of all the times I hear "Europeans are blank" and "Americans are blank" and "In Japan people are blank" and so on. Personally, I am not sure I can generalize over all Atlantans, my city of 8 years, much less over an entire continent.