I have also heard about how substances in banana could prevent HIV transmission. I’m not sure but as far as i know it has not been concluded. More research has to be done to test these compounds in HIV prevention. The theory was that certain compounds in bananas (lectins) could bind to cell infected with the HIV virus and prevent them from multiplying (replicating). Similar theories have been proposed for other plants. We will wait to hear from the scientist working in that area.