Short answer, IPAs. Or anything hoppy, I guess.
Because of the length of time needed to travel, beer had the propensity to spoil to a variety of bacteria. Yet, those that had a higher proportion of hops in the recipe appeared to survive without any significant product loss. This led to the requirement of hops not to offer a fulfilling flavor, but to stay fresh. Eventually, hops became a critical component in any beer recipe; a tradition that continues until today.
Although the beer bacterial burden was solved, microbiologists, curious individuals that they are, wanted to know why that was the case. The answer wasn’t known until 1937 when the antiseptic properties of hops were finally seen. When exposed to a hop extract, bacteria simply couldn’t survive. The finding not only gave more reason to drink hoppy beer, but also opened the door to a natural means of infection prevention.
For centuries, dentists have been trying to find natural means to prevent gum disease, which is an inflammatory process sparked by bacteria. When the antimicrobial activity of hops were found, dentists decided that it was at least worth a try. What they have found reveals that not only are they good for the mouth, they can potentially help to prevent problems in the future.
Through a series of experimental papers published over the last five years, we can understand exactly how hops help. In 2008, a team from Osaka University unveiled a group of chemicals known as polyphenols, which are known to help prevent oral cancer. Based on their experiments, these compounds stopped inflammation and kept gums pink instead of red. In the same year, a team from Nippon Dental University revealed the molecules also halted the development of dental plaque. By 2013, xanthohumol also proved to keep teeth happy and healthy by ensuring that bacteria could not stick to the teeth and gums.
Full article here.