S. Thermophilus: The Yogurt Strain
Streptococcus thermophilus has a long history as a probiotic. Found in fermented milk products along with its synergistic partner Lactobacillus delbrueckii subsp. bulgaricus, S. thermophilus has been used to make yogurt and similar fermented dairy foods for centuries. This includes skyr, a staple of Icelandic diets since the Viking age. Like other probiotics that have an affinity for dairy, S. Thermophilus' purpose is to turn lactose, the sugar in milk, into lactic acid. The increase in lactic acid transforms milk into the gel-like, metabolite-rich substance humans have enjoyed since ancient times and still enjoy today.
"Streptococcus" derives from a Greek term meaning "twisted kernel" and refers to the way the bacterium is grouped in chains that resemble a string of beads. "Thermophilus" derives from the Greek thermē, meaning "heat". Literally translated as "lover of heat," this organism thrives at high temperatures, hence its ability to ferment heated milk during yogurt production.
Wait, Isn't Streptococcus Bad?
Back to the genus portion of the name, Streptococcus bacteria often have a negative connotation and are commonly associated with Streptococcal pharyngitis or strep throat. While the genus Streptococcus includes several pathogenic species, such as strep throat-causing S. pyogenes and pneumonia and meningitis-causing S. pneumoniae, S. thermophilus is non-pathogenic and is believed to have developed separately from pathogenic species for at least 3000 years.
We've clearly formed a symbiotic relationship with this strain over the centuries. In fact, today S. thermophilus is one of the most widely used bacteria in the dairy industry. USDA statistics show that over a billion kilograms of mozzarella cheese and yogurt are produced from S. thermophilus each year.
The Health Benefits Of S. Thermophilus
Live cultures of S. thermophilus make it easier for people who are lactose-intolerant to digest dairy products. The bacteria break down lactose, the sugar in milk, that lactose-intolerant people find difficult to digest.
S. thermophilus has also been utilized as an adjuvant therapy, specifically in combination with conventional therapies to treat ulcerative colitis and inflammatory bowel disease.
Relief From Antibiotic-Associated Diarrhea
A study from 2003 found that those who ate yogurt containing S. thermophilus while being treated with antibiotics had lower rates of antibotic-associated diarrhea than the control group (12.4% vs. 23.7%). Researchers concluded that dietary supplementation with yogurt is a simple, effective, and safe treatment that decreases the incidence and duration of AAD.