Every time you open a package of cheese and the aroma hits your nose, it’s because of all the living microbes in the cheese. These microbes are what give cheese its aroma, colors, and flavor.
In the last decade, researchers found that many foods that we eat contain hundreds of microbial species with millions of bacteria. These foods include fruits, vegetables, fermented foods, and cheese. It turns out that ingesting all these millions of microbes is good for your health.
People tend to think of yogurt as a dairy food having lots of probiotics (beneficial bacteria), but don’t realize that cheese is also a great probiotic food.
Cheese is packed with a large variety of living microbes, which is why microbiologists say “Cheese is alive!” With every mouthful of cheese, you can ingest as many as 10 billion microbes!
The gut microbiome and cheese
The gut microbiome or microbiota is the huge community of bacteria, fungi, and viruses that live in our intestines. All these trillions of microbes are important for proper immune system function, for getting nutrients from foods, protecting us from harmful microbes (pathogens), and metabolic health.
The foods a person eats plays a big part in determining what species of bacteria live in the gut microbial community. When we eat cheese, we ingest their microbial communities. These microbes then travel through our intestines (the gut), and may even stay a while and colonize.
Propionibacterium bacteria Credit: CDC
Unique microbial communities in cheese
People have been eating fermented milk products such as cheese for thousands of years. Originally this was a way to preserve cow, sheep, or goat milk at room temperature for weeks or months at a time before refrigeration.
There are more than 2000 types of cheese! Cheeses that are not aged are fresh cheeses, and they are soft or even spreadable. Examples are mozzarella, ricotta, cream cheese, and feta. Most cheeses are hard cheeses, and these have been aged or ripened for months. Aging is a type of fermentation.
Each type of cheese has its own unique microbial community with many species of bacteria. Among the great variety of microbes in cheese are lactic acid bacteria, including many Lactobacillus bacteria species. They protect against harmful microbes. Some microbial species are unique to cheese, such as Penicillium camemberti (found in Camembert cheese)
The microbial communities found in cheese are influenced by all sorts of factors, such as whether the cheeses are made with starter cultures (a mix of specific bacteria) or not, whether raw or pasteurized milk is used, what ingredients are used (such as salt and herbs), the temperature, moisture, and ripening conditions. Even what the dairy cows ate, as well as the microbes that live in the production facilities and equipment (“house microbiota”) influence what microbes are in the cheese.
More microbial species are in the cheese rind than in the body of the cheese. In traditionally aged cheeses, the rind is a biofilm formed by multiple species of bacteria, yeasts, and molds (fungi) on the surface of the cheese.
Electron micrograph of a cheese rind with nearly 10 billion cells per gram. Credit: Rachel Dutton, American Society for Microbiology.
Medical advice regarding cheese is outdated
For many years medical advice has been to only eat low-fat cheese and low-fat dairy foods, and only in moderation. This is due to fears that the saturated fat in dairy foods would raise the LDL (bad) cholesterol and increase the risk of heart disease.
However, that advice is outdated. Recent studies find that eating both whole-fat and low-fat cheese frequently, even daily, is good for us. Health benefits include a lower risk of cardiovascular disease, diabetes, and hypertension. The microbes in cheese may be playing a role in these benefits.
What are the cheese microbes doing to me?
Researchers only recently started looking at how the microbes in cheese are involved in our health. This field is still in its infancy, but already health benefits are being found.
(The holes in Swiss cheese are made by the Propionibacterium freudenreichii bacteria.)
One well-done study found that eating a little Jarlsberg cheese every day is good for the bones as well as a person’s metabolic measures, such as total cholesterol levels. Jarlsberg contains the bacteria Proprionebacterium freudenreichii, which produces vitamin K and DHNA. The beneficial effects of Jarlsberg are from the vitamin K2 and DHNA in it - both necessary for bone health. (A low intake of vitamin K2 is linked with increased risk of bone fractures.)
An earlier study by the same Norwegian researchers found that eating 57 grams of Jarlsberg cheese (about 2 ounces) daily was optimal for health. In contrast, Camembert cheese does not naturally have vitamin K (and no Proprionebacterium freudenreichii bacteria), and does not have beneficial effects on bones.
Another study found that healthy young men who ate a little cow cheese daily or drank low-fat milk for 2 weeks had good changes in their gut microbiome (compared to a control group of men not consuming milk or cheese). The researchers were surprised that the cheese eaters had the biggest beneficial changes: an increase in short-chain fatty acids like butyrate and propionate, and lower levels of TMAO which transports cholesterol to the arteries.
Other studies found that eating cheese (e.g., Swiss type cheeses) frequently had increased amounts of beneficial gut microbes associated with health, as well as more gut microbial diversity. Studies found that after eating cheese (e.g., Parmesan cheese), microbes from the cheese lived in the human gut for at least a short time.
Which cheeses are best?
Eating a variety of cheeses appears to be best because this will result in consuming many microbial species. As with other foods, aim for moderate amounts – for example, two ounces or 57 grams per day.
Be sure to eat natural or traditional cheeses (e.g. Jarlsberg, cheddar, Gouda), but avoid pasteurized processed cheese.
Processed cheese, such as American cheese and Velveeta, do not contain microbes. Thus, they are not a probiotic food. Processed cheeses are made by blending natural cheeses (e.g., cheddar) with emulsifying agents, preservatives, thickeners, flavorings, and seasonings. They are not ripened or aged.
In some countries they can not even be called cheese, but instead are referred to as cheese food, cheese spread, or cheese product.
Most cheeses are aged or ripened (fermented) for weeks to months. Research is finding that fermented cheeses are more beneficial than non-fermented cheese – that they lower diabetes risk and cardiovascular disease risk.
It is known that there are lots of probiotic bacteria in Swiss cheese, Jarlsberg, Provolone, Gouda, cheddar, Edam, Gruyère, feta, Emmental, and Parmesan (Parmigiano-Reggiano). The good bacteria Propionibacterium freudenreichii (or P. shermanii) are found in Swiss type cheeses such as Emmental, Jarlsberg, and Leerdammer.
Nowadays most cheeses are made from pasteurized milk to which starter cultures are added. Pasteurized milk is milk that has been heat-treated between 145 to 162 degrees F to kill harmful bacteria, but which also kills some beneficial bacteria.
Raw milk cheeses have greater microbial diversity (both more species and numbers) than pasteurized cheeses. Raw milk has not been heat treated, which is why this milk has the most microbial diversity. Raw milk cheeses are required by the FDA to be aged for a minimum of 60 days at a temperature no less than 35 degrees F.
Soft unripened cheeses can become contaminated with harmful microbes (e.g., Listeria) that can be harmful to consumers, but this occurs rarely. This is because cheese-making is regulated by the government.
Because Listeria is so dangerous to a developing baby, pregnant women are advised to avoid certain soft cheeses (e.g., queso fresco) made from either raw milk and pasteurized milk.
Studies are concluding that eating cheese is a great way to support a healthy gut microbiome. Enjoy eating delicious cheese of all kinds!