Lactobacillus is a genus of beneficial bacteria found in the human gut, mouth, vagina, and certain foods. Healthy levels of these good bacteria within the human microbiome may help with digestion, absorption, and overall well-being. This article will discuss some of the most well-researched Lactobacillus species and their potential health benefits. Understanding the specific indications of probiotic species and strains is required for appropriate supplementation and meeting health goals.
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What is Lactobacillus spp.?
There are over 200 species of Lactobacillus, a bacteria of the Firmicutes phylum. Many species and strains are commensal organisms of the human microbiome and are found in probiotic supplements and fermented foods. There are numerous studies on the potential effects of Lactobacillus, including the formation of lactic acid, support of intestinal barrier integrity, production of B vitamins and short-chain fatty acids, and modulation of the immune system. (1)
What Are the Main Lactobacillus Species: What Are Their Health Benefits?
Below outlines and summarizes potential health benefits associated with the main Lactobacillus species.
Lactobacillus acidophilus
Lactobacillus acidophilus (L. acidophilus) is a good bacteria in the human oral, pulmonary (lungs), gastrointestinal, and genitourinary microbiomes. Supplementally, L. acidophilus is added to many probiotics in capsule, tablet, wafer, powder, and suppository form. Additionally, L. acidophilus is commercially added to many foods; it is used as a live culture in up to 80% of commercially-made yogurt in the United States. (2)
Diarrhea
L. acidophilus has been studied for its potential to help manage various types of diarrhea, including acute diarrhea caused by bacterial or viral infection, chronic diarrhea, and antibiotic-associated diarrhea (2).
Irritable Bowel Syndrome
Supplementation with L. acidophilus probiotics has been associated with improvements in abdominal pain and bloating in patients with irritable bowel syndrome (IBS) after 1-2 months.
Vaginal Health
Lactobacilli are the most predominant type of bacteria in the vagina, producing lactic acid that may help maintain a healthy balance of bacteria. Reductions in Lactobacilli can predispose an individual to bacterial vaginosis (BV) and vulvovaginal candidiasis. Oral and intravaginal administration of L. acidophilus may assist in maintaining vaginal health. (3, 4)
Skin Health
Eczema, or atopic dermatitis, is a dermatologic condition that causes dry, itchy, and inflamed skin. Eczema commonly presents itself in infancy, and dysbiosis is known to be a contributing factor to its development. One study has shown that probiotic administration containing L. acidophilus to pregnant women and their infants during the first three months of life was associated with a reduced prevalence of eczema in infants by 22%.
Lactobacillus brevis
Lactobacillus brevis (L. brevis) is commonly isolated from dairy products, fermented foods, and the intestinal and vaginal microbiomes. L. brevis is particularly beneficial for the stomach, and studies suggest it may help manage Helicobacter pylori infection, which is associated with stomach ulcers.
Lactobacillus casei
Lactobacillus casei (L. casei) is used in many probiotic formulations and has been studied for its potential health benefits, from supporting digestive function to promoting overall well-being.
Digestive Health
The ability to produce antimicrobial substances, enhance the epithelial barrier, compete for pathogenic binding sites, and modulate the immune system are all likely mechanisms by which L. casei supports digestive health and function. Research has shown benefits in managing colitis, antibiotic-associated diarrhea, and H. pylori infection with L. casei probiotics. (5, 6)
Allergies
Children colonized with L. casei have been observed to have a reduced risk of developing allergic diseases, like atopic dermatitis and asthma, by age five (5).
Metabolic Health
L. casei in the gut microbiome is associated with supporting healthy weight and blood glucose control. The ability of L. casei to modulate the immune system to reduce inflammation, along with its influence over insulin sensitivity, may contribute to these benefits. (5, 7)
Lactobacillus delbrueckii subsp. bulgaricus and lactis
These two species of Lactobacillus are largely used in the dairy industry for cheese and yogurt production. By modulating T cells of the immune system, L. delbrueckii may support systemic immunity and has been studied for its potential role in managing inflammatory bowel disease (IBD), liver health, and oral health. (8)
Lactobacillus fermentum
Because of its ability to produce antimicrobial peptides, the Lactobacillus fermentum (L. fermentum) has extended beyond human health and into food preservation. L. fermentum has been associated with supporting immune function, maintaining gastrointestinal and respiratory health, and promoting healthy cholesterol levels. (9)
Lactobacillus gasseri
Lactobacillus gasseri is beneficial in supporting many digestive and vaginal health functions.
Digestive Health
Research has shown the use of L. gasseri probiotics may be beneficial in supporting digestive health, including managing peptic ulcers, H. pylori infection, acute diarrhea, ulcerative colitis, and IBS. (10, 11)
Vaginal Health
L. gasseri is a well-documented species within the vaginal microbiome that may confer a protective effect against infection, such as BV. Its antimicrobial properties appear especially effective against Gardnerella vaginalis and Prevotella bivia, both associated with BV infection. (10, 12)
Weight Management
Several clinical trials have shown that supplementation of L. gasseri has been associated with a reduction in visceral fat mass in adults with obesity. (13, 14)
Lactobacillus helveticus
Lactobacillus helveticus (L. helveticus) is found naturally in the gut and certain foods like cheese, milk, and fermented vegetables. L. helveticus has been linked to supporting gastrointestinal, oral, and mental health.
Gastrointestinal Health
Consumption of L. helveticus probiotics may promote butyrate production, a short-chain fatty acid that supports gastrointestinal tract and systemic function. L. helveticus can modulate host immune responses and enhance protection against pathogens, potentially supporting gastrointestinal health. Other digestive benefits provided by L. helveticus include improving food tolerance by removing allergen proteins from foods and enhancing the bioavailability of nutrients. (15)
Mental Health
L. helveticus has been associated with increased serotonin, norepinephrine, and brain-derived neurotrophic factor levels in the brain, which are linked to reduced anxiety, depression, and cognitive dysfunction. Additionally, one study that gave elderly subjects fermented milk with L. helveticus reported improved sleep quality and quantity. Good quality sleep is known to reduce physiologic stress and improve mood. (16)
Lactobacillus paracasei
Lactobacillus paracasei (L. paracasei) is found in the mouth and intestinal tract, as well as in dairy products and fermented vegetables.
Infections and Immune Function
L. paracasei has been found to support the immune system, potentially reducing illness rates in children attending daycare and inhibiting the growth of pathogenic bacteria, including E. coli and Salmonella. In part, the ability to support immune function comes from L. paracasei's ability to stimulate the immune system and cytokine secretion. (17, 18)
Digestion
L. paracasei strains are resistant to heat and intestinal enzyme degradation, making it a common species in probiotic digestive formulas. Its anti-inflammatory properties, ability to promote the growth of Bifidobacterium spp., and enhancement of short-chain fatty acid production all support gastrointestinal health and digestive function. (18)
Lactobacillus plantarum
Lactobacillus plantarum (L. plantarum) can bind to the intestinal mucosa, increase the population of healthy bacteria within the microbiome, and confer anti-inflammatory properties to the host. Because of this, L. plantarum has been shown to support digestive health and may help manage pain and bloating in patients with IBS and skin symptoms in children with eczema.
A healthy population of L. plantarum within the microbiome may also support metabolic health, improving physical performance, maintaining a healthy weight, and supporting blood pressure (19).
Lactobacillus reuteri
Lactobacillus reuteri (L. reuteri) can influence the immune system and has been studied for its anti-inflammatory effects. L. reuteri may support the production of regulatory T (Treg) cells, which are involved in managing inflammation and promoting self-tolerance.
L. reuteri can support digestive function and may help manage gastrointestinal symptoms, including colic and constipation (20, 21). It is also a predominant species within the vaginal microbiome and can be used orally or intravaginally to support vaginal health.
Lactobacillus rhamnosus
Lactobacillus rhamnosus (L. rhamnosus) is found in the intestines and vagina and is commonly added to dairy products. Many studies support its potential health benefits and use in supporting various functions.
Digestive Health
L. rhamnosus has been shown to support the balance of microorganisms within the digestive tract and encourage the growth of other beneficial bacterial strains. L. rhamnosus increases the production of short-chain fatty acids and supports intestinal barrier function, which may help manage IBS symptoms. Additionally, supplementing L. rhamnosus during antibiotic therapy may reduce the risk of antibiotic-associated diarrhea. (22-24)
Oral Health
Several studies have shown reductions in oral bacterial overgrowth, gum inflammation, and cavities with probiotic supplementation of L. rhamnosus (25, 26).
Genitourinary Health
Various strains of L. rhamnosus have been studied for their potential role in supporting urinary tract health and vaginal health when given either orally or intravaginally.
What Are The Health Consequences of Unbalanced Lactobacillus in The Gut?
Given the numerous potential health benefits of lactobacilli, it's reasonable to expect that disruption to healthy and normal colonization could cause many downstream and unfavorable health effects.
Insufficient levels of beneficial Lactobacillus spp. can result in an elevated risk of infections, increased intestinal barrier permeability and inflammation, and decreased protective immunological factors. Dysbiosis has been linked to chronic digestive disorders, allergies, autoimmunity, and metabolic diseases.
The overgrowth of lactobacilli can also cause detrimental health effects, most often related to digestive symptoms like gas, bloating, abdominal pain and discomfort, indigestion, heartburn, reflux, constipation, and diarrhea. Nutrient malabsorption and symptoms of nutrient deficiencies can occur as well. (27)
What Causes Low Levels of Lactobacillus spp.?
Western dietary patterns, including high saturated and trans fats, high salt, and low fiber intake, have been associated with low levels of lactobacilli. A small study observing the effects of a gluten-free diet also noted reduced Lactobacillus spp. (28)
Acute and chronic stress can drastically affect the gut microbiome's composition, reducing beneficial bacteria levels and allowing pathogenic species to overgrow.
What Causes High Levels of Lactobacillus spp.?
Overgrowth secondary to digestive dysfunction, like low stomach acid, insufficient bile acids, pancreatic insufficiency, and reduced intestinal motility, can result in overgrowth of Lactobacillus spp.
High serum glucose levels have also been associated with increased Lactobacillus spp.
Specific dietary patterns and supplements can overstimulate the growth of lactobacilli, causing overgrowth. Plant-based diets rich in polyphenols, such as the Mediterranean diet, inulin supplementation, Lactobacillus-containing probiotics, and whey and pea proteins, are associated with increased levels of Lactobacillus spp. (28)
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How to Test Lactobacillus spp. Levels
Patient-collected fecal and vaginal samples are most commonly ordered to evaluate Lactobacillus colonies in the gastrointestinal tract and vagina.
Comprehensive Stool Test
Comprehensive stool analyses include an in-depth gut microbiome assessment through fecal specimens. Culture and PCR testing methods will analyze the health and quantity of Lactobacillus spp.
Vaginal Microbiome Analysis
A functional vaginal microbiome analysis is often recommended for patients with recurrent vaginal symptoms and infections to identify the diversity and abundance of the vaginal microbiome. Lactobacillus spp., and its most dominant species, are measured.
Foods That May Help Increase Lactobacillus spp. Levels
Certain dietary intake patterns are linked to predictable shifts in Lactobacillus levels. If trying to promote the growth of lactobacilli, foods that are correlated with elevated concentrations include (28):
- Whey and pea protein
- Unsaturated fats: avocados, nuts (almonds, hazelnuts, pecans, walnuts), seeds (pumpkin, sesame, flax), fish, oils (olive, peanut, canola, corn, soybean)
- Fiber: whole fruits and vegetables, nuts and seeds, whole grains, legumes
- Resistant starch: brown rice, beans, lentils, plantains, green bananas, oats, potatoes
- Cultured milk and dairy
- Fermented foods: kimchi, sauerkraut, kefir, kombucha, natto, pickled vegetables
- Polyphenol-rich foods: fruits, vegetables, seeds, tea, cocoa, wine
The Mediterranean diet has been shown to be associated with increased Lactobacillus intestinal colonies specifically. A high intake of monounsaturated and polyunsaturated fats, polyphenols and antioxidants, fiber, low glycemic carbohydrates, and vegetables associated with the diet can explain this. (28)
Supplements that May Help Increase Lactobacillus spp. Levels
Prebiotic and probiotic supplements are often recommended to support Lactobacillus growth. Many probiotics are available, each containing a slightly different combination of Lactobacillus strains. The probiotic choice should be based on lab results and desired health outcomes.
Prebiotics are nutrients that fuel probiotic species that are categorized into five main groups:
fructans, galactooligosaccharides, starch and glucose-derived oligosaccharides, other oligosaccharides, and non-carbohydrate oligosaccharides. Prebiotic supplements contain one or several of these to support the growth of lactobacilli and other beneficial microbiome bacteria. Probiotic formulas will often also include prebiotics to improve their efficacy.
How to Make Sure You Are Getting High-Quality Lactobacillus spp. Supplements
Good-quality probiotic supplements are essential for their efficacy. The following characteristics have been identified as important properties for lactobacilli to be effective probiotic organisms:
- Adherence to epithelial cells
- Reduce pathogenic adherence to epithelial cells
- Ability to persist and multiply
- Production of lactic acid, hydrogen peroxide, and antimicrobial chemicals
- Resistance of vaginal microbicides
- Safety: noninvasive, noncarcinogenic, and nonpathogenic
- Formation of a balanced flora
Probiotic supplements' quality, purity, and strength are essential for efficacy. Choosing a cGMP-compliant, third-party-tested supplement ensures that the manufacturer has followed regulatory and quality requirements to produce a safe, effective, and shelf-stable product. Additionally, selecting a probiotic that has listed bacterial strains on the nutritional label that have been studied in clinical trials is important. Because the efficacy of probiotics is strain- and condition-specific, both need to be considered when making recommendations and choosing the correct probiotic supplement. (29, 30)
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Summary
Our understanding of the human microbiome is rapidly evolving as research continues to uncover the multitude of potential health benefits provided by the beneficial organisms that coexist within the body. Lactobacillus spp. is a group of beneficial lactic acid-producing bacteria that is comprised of over 200 distinct species. While more research is required, existing evidence supports a wide array of potential health benefits that healthy levels of lactobacilli may provide to the body. Specialty labs can help quantify an individual's levels of lactobacilli in the body, and dietary and supplemental interventions can be implemented as needed to support healthy Lactobacillus spp. growth and a happy and healthy microbiome.
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