Fermented foods are known to be good for you, and good old-fashioned sauerkraut made by fermenting cabbage with lactic acid bacteria is no exception. Claudia Stäubert and colleagues at Leipzig University were investigating hydroxycarboxylic acid (HCA) receptors when they discovered that a molecule produced by sauerkraut bacteria, D-phenyllactic acid, binds strongly to one of those receptors, HCA3 (PLOS Genet. 2019, DOI: 10.1371/journal.pgen.1008145). The team fed volunteers sauerkraut and found high levels of D-phenyllactic acid in their blood and urine, high enough to activate the volunteers’ immune cells. This observation suggests that sauerkraut plays a physiological role as well as a nutritional one, a finding that Thue Schwartz of the University of Copenhagen says is “truly interesting.”
HCA3 is found in only humans and apes. By using bioinformatics, Stäubert’s team showed that the gene for HCA3 entered the ape genome around the same time as did the gene for alcohol dehydrogenase, which helps us break down toxic alcohols. These findings make a “compelling case” that a change in diet modified the molecular biology of our primate ancestors, says Steven Benner of the Foundation for Applied Molecular Evolution.