The bacteria that give cheese its flavor and those marketed in probiotic capsules are, in several cases, the same organisms. That overlap is not new information. What has not been done is to watch which of them are actually present in a specific cheese at the moment someone eats it, rather than at the moment it was made.
Researchers at the University of Reading's Food Microbial Sciences Unit did exactly that with three cheeses from Nettlebed Creamery near Henley in Oxfordshire, sampling at multiple points during maturation and analyzing both bacterial populations and chemical composition. The paper appeared May 1 in ACS Food Science and Technology, and a second press cycle put it back into circulation this month.
Eight Days, Several Weeks, Nine Months
The three cheeses were chosen for how differently they age. Bix is a soft bloomy-rind cheese that matures in about eight days. Highmoor is a semi-soft, washed-rind cheese with an orange crust that takes several weeks to develop. Witheridge is a semi-hard cheese wrapped in hay and aged around nine months. A fourth sample, a batch of Witheridge made with unpasteurized milk, was included for comparison.
Time changed the picture considerably. Bix, with the least of it, was dominated by Lactococcus lactis at both sampling stages. The longer-aged cheeses developed substantially more complex communities, and L. lactis, while present throughout all three, saw its share fall sharply in Highmoor and Witheridge as other species moved in.
Streptococcus thermophilus, the same species used as a yogurt starter, was found only in the semi-soft and hard cheeses and stayed dominant in both through maturity. Highmoor and Witheridge also contained Propionibacterium freudenreichii, added deliberately for nutty flavor and for the carbon dioxide that produces the holes in some cheeses. It also produces propionic acid, a short-chain fatty acid associated in other research with anti-inflammatory activity, reduced cholesterol synthesis, and appetite regulation.
Lactose was almost entirely gone from all three by maturity, broken down by lactic acid bacteria during fermentation, which is relevant to anyone who avoids dairy for that reason.
The Rind Is Doing Something Too
The white mold that forms the rind on the soft cheese produces chitin. Chitin is a dietary fiber, and the researchers suggest it may function as a prebiotic, meaning food for beneficial bacteria already resident in the gut rather than a source of new ones.
Whether that survives a trip through the stomach in useful quantity is not something this study measured.
The team also proposes that cheese itself may be an unusually good delivery vehicle. Lead author Sabrina Longley, a PhD researcher in the Department of Food and Nutritional Sciences, said in coverage of the findings that "the matrix of fats and proteins in the cheese may also help protect the bacteria as they travel along the digestive tract." That is a plausible mechanism and a stated hypothesis, not a measured result.
What the Study Never Measured
No human ate anything. There were no participants, no in vivo testing, and no measurement of what happens to any of these bacteria after consumption.
Every health-related claim attached to this work is therefore inferential, drawn from what is known about these species and compounds from other research. The authors say so, and they specify what would settle it: dietary intervention trials tracking how gut microbiota actually change after people eat the cheese.
There is a second limitation worth knowing. The sequencing approach used here identifies bacteria, not yeasts or molds, which means Bix in particular is likely to be more microbially complex than the results show, since bloomy-rind cheeses are ripened partly by fungi the method could not see.
The word "probiotic" also has a technical definition that this study does not meet. A probiotic is a live organism shown to confer a health benefit at an adequate dose. What was demonstrated here is the presence of species with recognized probiotic potential, which is a different and weaker claim.
Who Paid for the Cheese
The lead author is a cheesemaker at Nettlebed Creamery, which supplied the cheeses and part-funded the study. She is completing her PhD part-time on a University of Reading regional bursary. The creamery describes the collaboration openly on its own website.
Disclosure is how this is supposed to work, and the sequencing data does not become wrong because a creamery funded it. But a study of one producer's three cheeses, co-authored by someone who makes them, is a narrow evidence base for any general claim about artisan cheese.
Two other things are in view. Cheese remains high in saturated fat and sodium, and nothing in this research addresses that side of the ledger. And one of the four samples was made with raw milk, a category that carries its own documented safety considerations, separate from anything related to gut health. Anyone managing blood pressure, cholesterol or a dairy-related condition should treat this as interesting microbiology rather than dietary guidance, and take diet questions to a clinician or registered dietitian.
Key Questions Answered
What did the researchers actually do?
They sampled three artisan cheeses at multiple stages of maturation and analyzed the bacterial communities and chemical compounds present in each.
Which bacteria were found?
Lactococcus lactis in all three, Streptococcus thermophilus dominant in the semi-soft and hard cheeses, and Propionibacterium freudenreichii in the washed-rind and hay-aged varieties.
Does eating these cheeses improve gut health?
Unknown. No humans were tested. The health claims are inferred from what is known about these species elsewhere, and dietary intervention trials are needed.
Should people eat the rind?
The soft cheese rind mold produces chitin, a fiber that may act as a prebiotic. Whether it does so in practice was not measured.
Is there a conflict of interest?
Yes, and it is disclosed. The creamery whose cheeses were studied part-funded the work, and the lead author is one of its cheesemakers.
Does this make cheese a healthy food?
No. The study says nothing about saturated fat or sodium, and it examined three cheeses from a single producer, which is a narrow basis for drawing general dietary conclusions.
