Improving Gut Health and Digestive Function
Active lactic acid bacteria, a significant group of probiotics, are indispensable for maintaining a healthy and balanced gut microbiome. They support the digestive system by fermenting carbohydrates to produce lactic acid and other organic acids, which lower the pH in the gut. This acidic environment is unfavorable for many harmful bacteria, inhibiting their growth and allowing beneficial flora to thrive. This process, known as competitive exclusion, helps protect against intestinal infections.
Alleviating Lactose Intolerance
Certain LAB strains can improve lactose digestion. Many LAB, such as Lactobacillus delbrueckii subsp. bulgaricus, produce lactase, an enzyme that breaks down lactose in fermented dairy products like yogurt and kefir. This makes these foods easier to digest for those with lactose intolerance.
Preventing Diarrhea and Constipation
Organic acids produced by LAB help regulate bowel function. They can prevent both constipation and diarrhea by promoting intestinal movement and inhibiting harmful bacteria and viruses. Specific strains like Lactobacillus reuteri and Lactobacillus rhamnosus can reduce the duration and severity of diarrhea.
Strengthening the Immune System
Active lactic acid bacteria play a critical role in modulating and strengthening the human immune system. A balanced gut microbiota is linked to a robust immune response, and LAB are central to this connection. They enhance immune function by interacting with intestinal immune cells and stimulating the production of serum Immunoglobulin A (IgA), an antibody crucial for mucosal immunity.
LAB can enhance phagocytosis, increase the activity of natural killer cells, and stimulate other immune responses against pathogens. This leads to increased resistance against numerous disease conditions and infections. Some strains can down-regulate pro-inflammatory cytokines, helping to prevent inflammatory conditions. This immunomodulatory effect is a cornerstone of the health-promoting properties associated with probiotic LAB.
Enhancing Food Quality and Safety
Active lactic acid bacteria have been used for centuries to enhance food quality and safety through fermentation. Their metabolic activities offer a natural method of food biopreservation.
- Flavor and Texture Development: LAB produce metabolites like organic acids, aromatic compounds, and exopolysaccharides (EPS). These are responsible for the characteristic flavors, textures, and aromas of fermented foods such as yogurt, cheese, and sourdough bread. EPS, for example, act as natural thickeners.
- Biopreservation and Pathogen Inhibition: Organic acids and bacteriocins produced by LAB create an acidic environment that inhibits the growth of foodborne pathogens and spoilage microorganisms, extending shelf life. Nisin, a bacteriocin from Lactococcus lactis, is used commercially as a food preservative.
- Reduction of Toxins: Certain LAB strains can help detoxify harmful compounds like mycotoxins through adsorption and enzymatic degradation.
Comparison of LAB vs. General Lactic Ferments
While often used interchangeably, not all lactic ferments provide health benefits as probiotics.
| Feature | Active Lactic Acid Bacteria (Probiotics) | General Lactic Ferments |
|---|---|---|
| Viability | Remain alive and active through the digestive tract. | Many do not survive the acidic stomach environment. |
| Effect on Host | Colonize the intestinal mucosa and actively interact with the host's body. | Primarily act chemically within the food product, producing lactic acid. |
| Beneficial Actions | Contribute to balancing the gut flora, modulating immune function, and producing specific bioactive compounds. | Produce lactic acid, which preserves food and contributes flavor, but offer no sustained probiotic effect in the gut. |
| Colonization | Adhere to the intestinal walls and can transiently colonize the gut. | Pass through the digestive system without colonizing the intestinal walls. |
Nutritional Enhancement and Other Health Effects
Active LAB fermentation enhances the nutritional profile of foods and improves nutrient absorption. By breaking down complex compounds, LAB make minerals and vitamins more bioavailable. LAB can also synthesize essential vitamins like B12, folate, and riboflavin during fermentation.
Beyond digestion and immunity, some studies link LAB to benefits like lowering serum cholesterol levels, improving cardiovascular health, and potentially influencing mood via the gut-brain axis. The evidence suggests a wide array of potential systemic benefits from incorporating active LAB into the diet.
Fermented Foods Containing Active Lactic Acid Bacteria
- Yogurt: Made from milk fermented by LAB like Lactobacillus bulgaricus and Streptococcus thermophilus. Look for "live and active cultures".
- Kefir: A fermented milk drink using kefir grains, a culture of LAB and yeast.
- Sauerkraut: Fermented cabbage, a source of various LAB including Lactobacillus plantarum.
- Kimchi: Korean fermented cabbage and vegetables, often containing Lactobacillus kimchii.
- Miso: Japanese seasoning from fermented soybeans with koji fungus.
- Sourdough Bread: Fermented by naturally present lactobacilli.
- Traditional Buttermilk: Liquid left after churning butter, contains natural LAB.
Conclusion
The benefits of active lactic acid bacteria are extensive, impacting digestive health, immunity, food safety, quality, and nutritional value. As agents of fermentation, they serve as natural preservatives, enrich flavors, and enhance nutrient bioavailability. By balancing the gut microbiome and strengthening immune responses, specific probiotic LAB contribute significantly to human health. Their role in mitigating lactose intolerance and other conditions highlights the importance of including foods rich in live cultures as part of a healthy diet. For more information on gut microbiota, visit the National Institutes of Health.(https://pmc.ncbi.nlm.nih.gov/articles/PMC8305854/).
