Lactobacillus bulgaricus (Lactobacillus delbrueckii subsp. bulgaricus)
Synopsis
Lactobacillus bulgaricus is a thermophilic (heat-loving), rod-shaped bacterium that plays a key role in the fermentation of yogurt and other cultured dairy products. It works symbiotically with Streptococcus thermophilus to convert lactose into lactic acid, which gives yogurt its tangy taste and thick texture. This lactic acid also helps inhibit the growth of spoilage organisms and supports the digestion of lactose for people who are mildly lactose intolerant.
While not as resilient in the gastrointestinal tract as some other probiotic strains like L. acidophilus or Bifidobacterium longum, L. bulgaricus still contributes to digestive health by enhancing nutrient absorption, reducing inflammation, and supporting immune responses—especially when consumed regularly through live cultures. It is often used in probiotic-rich foods rather than standalone supplements due to its relatively low survivability during digestion. Nevertheless, yogurt made with active L. bulgaricus is associated with improved gut function, modulation of the microbiome, and enhanced intestinal barrier integrity.
Its ability to break down milk proteins and fats into bioactive peptides also supports its use in functional nutrition, where it may help with metabolic health, cholesterol regulation, and antioxidant defense.
Historical Use:
Lactobacillus bulgaricus has one of the most storied pasts among probiotic organisms. It was first identified in 1905 by Bulgarian microbiologist Stamen Grigorov, who isolated the bacterium from traditional Bulgarian yogurt. This discovery was instrumental in advancing the understanding of beneficial microbes in food. Shortly after, Nobel laureate Élie Metchnikoff of the Pasteur Institute championed the health benefits of fermented milk, particularly yogurt made with L. bulgaricus, as part of his theory that lactic acid bacteria could delay aging and improve longevity. He linked the long lives of Bulgarian peasants to their high intake of fermented dairy.
But the use of fermented milk long predates this scientific recognition. Across Central and Eastern Europe, the Middle East, and parts of Asia, people consumed yogurt-like products for thousands of years—not just for nourishment but also for digestive and immune support. Yogurt was often given to children, the elderly, and the sick as a fortifying food that was gentle on the stomach. In some traditions, it was believed to cleanse the gut, improve complexion, and even calm fevers or gastrointestinal infections.
Though early practitioners had no knowledge of microbial species, their generational wisdom about fermented foods indirectly made use of L. bulgaricus. Its legacy continues today, bridging the gap between folk medicine and modern probiotic science.
Uses: Health Conditions
Antibiotics (side effects of) (Scientific)
Acid Indigestion (Scientific)
Antibiotics (alternatives to) (Scientific)
Allergies (food) (Scientific)
Allergies (respiratory) (Neither)
Anemia (Neither)
Appetite (deficient) (Neither)
Asthma (Neither)
Bladder Infection (Neither)
Cancer Treatment (reducing side effects) (Neither)
Chemotherapy (reducing side effects) (Scientific)
Colitis (Scientific)
Constipation (adults) (Scientific)
Constipation (children) (Scientific)
Diarrhea (Scientific)
Digestion (poor) (Scientific)
Diverticulitis (Neither)
Gastritis (Scientific)
Irritable Bowel Syndrome (Scientific)
Lactose Intolerance (Scientific)
Leaky Gut Syndrome (Scientific)
Liver Detoxification (Neither)
Oral Surgery (Scientific)
Ulcers (Scientific)
Urinary Tract Infections (Neither)
Vaginitis (Scientific)
Body Systems
Digestive System (Science)
Immune System (Science)
Intestinal System (Science)
Peyer’s patches (Traditional)
Gastrointestinal Tract (Traditional)
Large Intestines (Colon) (Traditional)
Small Intestines (Traditional)
Appendix (Traditional)