Is Lactic Acid Bacteria a Probiotic? The Scientific Answer Explained

Lactic acid bacteria are used in the production of countless fermented foods, from yogurt to kimchi, and have been for centuries. However, despite their widespread use and general association with health, not all lactic acid bacteria are technically probiotics, and understanding the distinction is crucial.

Quick Summary

A specific lactic acid bacterium must meet strict criteria, including a proven health benefit, to be classified as a probiotic. The term refers to a functional property, not an entire group of microorganisms.

Key Points

• Functional vs. Categorical: Lactic acid bacteria (LAB) is a broad microbial category, while a probiotic is a specific functional designation for a strain with proven health benefits.

• Strain Specificity is Key: A probiotic's health effects are strain-specific. A benefit observed in one strain cannot be assumed for another, even within the same species.

• Survival is Essential: To be a probiotic, the LAB strain must be alive and survive the acidic stomach and bile to reach the gut in sufficient quantities.

• Backed by Evidence: True probiotics require documented scientific evidence, typically from human clinical trials, to support specific health claims.

• Check Labels Carefully: Informed consumers should look for products that specify the genus, species, and strain of the probiotic, as well as the CFU count at the time of expiration.

• Diverse Benefits: Probiotic LAB support gut health by modulating the immune system, competitively excluding pathogens, and producing beneficial compounds like short-chain fatty acids.

Understanding Lactic Acid Bacteria (LAB)

Lactic acid bacteria (LAB) form a large group of microorganisms known for fermenting carbohydrates into lactic acid. This process is essential for creating many fermented foods and acts as a natural preservative by lowering pH, which inhibits harmful bacteria. LAB are found in plants, fermented foods, and digestive systems of humans and animals. The group is diverse, including genera like Lactobacillus, Lactococcus, and Streptococcus, with Lactobacillus recently reclassified into 25 new genera.

Key characteristics of LAB

• Fermentation: Produce lactic acid, lowering pH and preserving food.
• Flavor and Texture: Contribute to the taste and texture of fermented foods.
• Diversity: Includes many genera and species.

What is a Probiotic?

A probiotic is defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host". This definition highlights key differences from the broader LAB group:

• Live Microorganisms: Must be alive and viable when consumed and in the gut.
• Adequate Amounts: A specific, sufficient dose is needed for the benefit.
• Proven Health Benefit: Requires scientific evidence from human clinical trials.
• Strain Specificity: Benefits are specific to the exact strain, not the species or genus.

The Difference: Lactic Acid Bacteria vs. Probiotics

While many probiotics are LAB, not all LAB are probiotics. LAB is a broad category, while probiotic is a functional term for specific, proven strains. A LAB must meet strict criteria to be considered a probiotic.

Key factors that distinguish a probiotic LAB

• Survival: Must survive the stomach's acidic environment and bile to reach the gut alive.
• Adhesion: Should adhere to or reside in the intestinal lining to interact with the host.
• Documented Efficacy: Must have scientific evidence for a specific health claim.

Table: Comparison of LAB and Probiotics

Feature	Lactic Acid Bacteria (LAB)	Probiotics
Classification Level	Broad group of bacteria defined by metabolism	Functional designation for a specific strain
Required to be Alive?	Often added live, but may be dead in final product (e.g., sourdough bread)	MUST be live and viable in adequate amounts
Survival in Gut?	No guarantee; many strains are killed by stomach acid	Must demonstrate the ability to survive transit
Proven Health Benefit?	Not a requirement; main function may be fermentation	A prerequisite, supported by clinical evidence
Found In	Yogurt, kimchi, sauerkraut, sourdough, cheese	Supplements, specific yogurts and other fortified foods

Examples of Lactic Acid Bacteria with Probiotic Properties

Many well-known probiotic strains belong to the LAB family after meeting the necessary criteria.

• • Lactobacillus species: A source for many probiotics like Lactobacillus rhamnosus GG.
• • Bifidobacterium species: Closely related to LAB and commonly used in probiotics, such as Bifidobacterium animalis subsp. lactis.
• • Streptococcus thermophilus: Used in yogurt production and recognized for probiotic potential.
• • Saccharomyces boulardii: A probiotic yeast, not bacteria.

The Health Benefits of Probiotic LAB

Probiotic LAB offer host benefits, mainly in gut health, through various mechanisms:

• Immune System Modulation: Interact with gut immune tissue.
• Competitive Exclusion: Compete with pathogens for space and nutrients.
• Antimicrobial Production: Produce substances inhibiting pathogen growth.
• Intestinal Barrier Reinforcement: Strengthen the gut lining.
• Nutrient and Metabolite Production: Produce beneficial compounds like SCFAs and aid digestion.

How to Choose a Probiotic Product

Given the importance of strain specificity, look for products that provide detailed information:

1. Strain Designation: Genus, species, and specific strain name should be listed.
2. CFU Count: Look for the number of live Colony Forming Units guaranteed through the product's shelf life.
3. Targeted Benefit: Choose a product with clinical evidence for the health outcome you desire.
4. Reputable Brands: Select brands with transparent labeling and scientific backing. The International Scientific Association for Probiotics and Prebiotics (ISAPP) is a valuable resource. https://isappscience.org/for-consumers/.

Conclusion

In summary, not all lactic acid bacteria are probiotics, although many probiotics are LAB. The key differentiator is scientific evidence demonstrating a specific health benefit for a particular strain when consumed in adequate amounts. Understanding this distinction helps consumers make informed choices about fermented foods and probiotic supplements, recognizing the science behind microbial health benefits.

Frequently Asked Questions

Does eating fermented food mean I am consuming probiotics?

Not necessarily. While fermented foods like yogurt, sauerkraut, and kimchi are made using lactic acid bacteria (LAB), not all of these products contain viable probiotic strains at the time of consumption. Cooking or pasteurization kills the live bacteria, and even raw fermented foods may not contain strains with scientifically proven benefits.

What is the primary difference between LAB and probiotics?

The primary difference is the level of specificity and scientific validation. LAB is a broad category of bacteria defined by its metabolic activity of producing lactic acid, while a probiotic is a specific, well-defined strain that has been scientifically proven to confer a health benefit.

Do probiotic supplements use lactic acid bacteria?

Many, but not all, probiotic supplements contain strains of lactic acid bacteria, primarily from the Lactobacillus and Bifidobacterium genera. However, some also use yeasts like Saccharomyces boulardii or spore-forming bacteria like Bacillus.

Why is strain specificity important for probiotics?

Strain specificity is important because a probiotic's health effects are dependent on the unique genetic and functional properties of that specific strain. For example, one strain might help with diarrhea, while a different strain of the same species may not have that effect.

How can I tell if a yogurt contains probiotics?

To know if a yogurt contains probiotics, check the label for specific strain names (e.g., Bifidobacterium animalis subsp. lactis DN-173 010) and a live and active cultures seal. A high CFU count is also a good indicator, though it doesn't guarantee a probiotic effect without clinical evidence.

Do non-dairy fermented foods, like pickles, contain probiotics?

While many pickles are made using lactic acid fermentation, commercial varieties are often pasteurized, which kills the beneficial bacteria. However, naturally fermented pickles or sauerkraut that are not heat-treated may contain live LAB, though their probiotic status and benefit are often unproven.

What are some of the health benefits associated with probiotic LAB?

Scientifically-backed probiotic LAB strains can offer numerous health benefits, including improving gut microbiota balance, aiding in digestion, boosting the immune system, and helping to alleviate certain digestive symptoms like diarrhea or irritable bowel syndrome (IBS).