If someone from another country/culture who is visiting the U.S. does not use deodorant, is there a polite way to tell them that is the custom in the U.S.?

How can you bring up the fact that someone has strong body odor without embarassing them? The person I am thinking of is here to do a speaking tour and will be traveling the country. Is there a way to bring up the topic while still being dignified and respectful?