Many people take a close look at the list of ingredients on packages of food they buy. Whether they want to check for added sugar, gluten content, egg ingredients, artificial colorings, MSG, etc., people are becoming more and more educated and concerned about what they’re putting into their bodies. That’s why it’s always disconcerting to find out that something you thought was safe to eat may not actually be safe.
Part of the movement towards healthier eating has spurred many people to eat sprouted, fermented, or otherwise traditionally preserved foods. Fermentation in particular requires the use of yeast, whether naturally occurring from the environment or added as in the fermentation of beer or wine. One yeast in particular that has important uses both in the food industry and in production of ethanol is Pichia kudriavzevii. While it was always known to be related to Candida krusei, a recent study that mapped the genomes of both yeasts found that they were both essentially the same species, sharing 99.6 percent of their DNA. That’s concerning on many levels.
Candida krusei is a leading cause of clinical yeast infections and is deemed to be a pathogenic yeast. Even worse, it is resistant to fluconazole, one of the primary drugs given to patients suffering from yeast infections and some forms of meningitis. While P. kudriavzevii has previously only been considered an opportunistic pathogen that afflicts those suffering from compromised immune systems, the recent study highlighting its identity with C. krusei may mean that P. kudriavzevii is just as dangerous. And that means that continuing to rely on it for the production of fermented foods could lead to fungal infections among some consumers.
As of right now, P. kudriavzevii is still considered to be “generally recognized as safe” by the FDA due to its use in producing fermented cacao, fermented milk, and in starter cultures for sourdough bread. But since both P. kudriavzevii and C. krusei show the same anti-fungal resistance, maybe it’s time for the FDA to take a closer look and assess what potential risk there is from the use of these yeast in commercial food production.