Streptococcus thermophilus is a bacterium frequently encountered in fermented foods, especially dairy products. Despite sharing the “Streptococcus” genus name with some disease-causing bacteria, S. thermophilus is widely recognized as a beneficial organism. This distinction is important for understanding its role in both food production and human health.
Understanding Streptococcus Thermophilus
Streptococcus thermophilus is a type of lactic acid bacterium, a group of microorganisms known for converting sugars into lactic acid. It is a Gram-positive bacterium and a facultative anaerobe, meaning it can thrive in environments both with and without oxygen. This bacterium is also non-motile and does not form spores.
This organism belongs to the Streptococcus genus but is genetically distinct from pathogenic species like those causing strep throat or pneumonia. It lacks the specific genes and surface proteins that enable harmful streptococci to adhere to tissues and evade host defenses. It has even received “Generally Regarded As Safe” (GRAS) status from the FDA and “Qualified Presumption of Safety” (QPS) status from the European Food Safety Authority.
S. thermophilus is commonly found in milk and milk products, where it is extensively used as a starter culture. Its name, “thermophilus,” translates to “heat-loving,” reflecting its optimal growth at warmer temperatures. This heat tolerance makes it suitable for the fermentation processes in producing various dairy items.
Its Role in Health and Food
Streptococcus thermophilus plays a role in fermented dairy products. It is widely used in making yogurt and cheese, where it works with Lactobacillus bulgaricus. This cooperation enhances fermentation, contributing to the characteristic texture and tangy flavor of these foods.
Beyond its industrial applications, S. thermophilus is recognized for its probiotic benefits, influencing digestive health. As a probiotic, it can survive the acidic conditions of the stomach and the presence of bile to reach the intestines. Once in the gut, it contributes to a balanced microbiota by competing with less beneficial bacteria and supporting the growth of healthy microbes.
A health benefit of S. thermophilus is its ability to aid in lactose digestion. It produces the enzyme lactase, which breaks down lactose, the sugar found in milk, into simpler, more digestible sugars. This action can reduce digestive discomfort for individuals who are lactose intolerant. It also contributes to gut health by producing short-chain fatty acids, beneficial for the intestinal lining.
Rare Considerations for Harm
While Streptococcus thermophilus is considered safe and beneficial, there are rare circumstances where it could be associated with adverse effects. These instances are confined to individuals with compromised immune systems. For example, patients undergoing intensive medical treatments like chemotherapy or those who have received organ transplants may have a weakened intestinal barrier, which could allow bacteria to enter the bloodstream.
In such vulnerable populations, there have been case reports of bacteremia, an infection in the bloodstream, linked to S. thermophilus. Other rare associations include bacterial meningitis or endocarditis, an infection of the heart’s inner lining. These cases are uncommon and generally occur with severe underlying health conditions or compromised gut integrity.
General consumers rarely experience adverse reactions to S. thermophilus. Some individuals might experience mild gastrointestinal discomfort, such as gas or bloating, when first introducing probiotics. Allergic reactions are also possible, though infrequent. For the majority of the population, consuming S. thermophilus through fermented foods or supplements poses no known health risks.