Probiotics. The new darling of health and advertising. Do cheeses really contain any of these amazing, essential microbes?
While I have no letters after my name (unless I capriciously add them), it doesn’t require a university degree to understand that bacteria, both beneficial and hurtful, can only live under certain contidions. I am a cheesemaker and I study science as it relates to dairy. I know what cultures I add to milk to make cheese. Very few of these are currently considered probiotic. And even if they were, when cheese is aged, the bacteria gradually die off as they run out of food to metabolize. So even when probiotic cultures are used, they do not survive longterm aging*. In fact, I was at a conference in England this last summer where research into genetically modifying probiotic bacteria to survive cheesemaking and aging was discussed. (Without much enthusiasm on the part of the artisan cheesemakers present, I might add!)
* I did find that some aged cheeses are commercially being designed to include probiotic bacteria that survive long term aging. These cheeses are labeled as containing probiotics and are not available widely as of yet. I think you can expect to see more products such as this in the future- if nothing else, they will be introduced for the market value they will bring.
I was doing some research today for my latest book (on raw milk production and consumption). I was reading a on probiotics that I chose for it’s high ranking and great reviews on Amazon. After perusing the front chapters, I skipped to the section containing information about cheese and dairy products – and immediately had to begin putting yellow highlighter frowny faces in the margins (my system for reviewing books). At first I wondered if perhaps my information was wrong, but then found another contradiction that basically confirmed that the author was not really aware of at least this portion of his subject. (I sure hate it when what you think is going to be a reputable source, turns out to be suspect.)
So lets go over a few basic things that you can always apply to probiotics -to help determine for yourself if a food is a good source of these helpful bacteria.
- In order to be probiotic, the bacteria must survive the harsh environment of our stomach and travel on to the next portions of our digestive system. Not very many bacteria have this capability – the stomach is one of the first defenses against bacterial contamination of food!
- Probiotic bacteria in food must have a source of nourishment – or they will die (unless, of course, they are held in stasis through something such as freezing). This is true of all bacteria. Once a food is fully fermented, the bacteria begin to perish unless fermentation is suspended – through refrigeration or some other means. Even then, their life span is limited.
- High heat, such as scalding or boiling, kills all but bacteria that are capable of forming spores that protect them from the heat. So even if milk or cheese or whey contains probiotic bacteria if it is cooked they will die.
The bacteria currently considered probiotic include only a couple of strains regularly used in making cheese. A fresh cheese that uses these bacteria as a part of its fermentation process will likely have some of these helpful microbes still living, but the longer a cheese is aged, the fewer bacteria remain alive. Aged hard cheeses are not sterile, but the life forms found on and around them are typically environmental, not those that were added during the cheesemaking process. In cheeses made using high heat and added acid, such as whey and milk ricotta, any probiotic bacteria in the whey will be killed during the high heat treatment (along with enzymes and milk’s natural defensive systems).
Bottom line, don’t look to aged cheeses as a probiotic source, yogurt is a no-brainer if probiotics are your goal! Instead, enjoy aged, natural cheeses for what they are meant to be – deliciously preserved (usually through fermentation) milk.
P.S.: So where can you find information on probiotics that you can trust? Hard to say! Popular topics are a magnet for publishers and writers. The best advice is to consult more than one source, preferably those that list scientific studies as their sources – but of course all the studies that will be helpful have not been done, nor is science a static subject.
Oh, here are a couple of sources I used to write this post:
Vet. Med. – Czech, 47, 2002 (6): 169–180 Review Article 169 – Lactic Acid Bacteria, Probiotics and the Immune System
R. HERICH, M. LEVKUT
Department of Pathology, University of Veterinary Medicine, Košice, Slovak Republic
J Dairy Sci. 1987 Jan;70(1):1-12.
Survival of lactic acid bacteria in the human stomach and adhesion to intestinal cells.
Conway PL, Gorbach SL, Goldin BR.
http://www.dairycouncilofca.org/pdfs/probiotics.pdf, “Friendly Bacteria with a Host of Benefits”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC106298/ Probiotic Cheese