All the growing interest surrounding probiotics has led to an explosion in the supplement market,1 which is estimated to be valued at $45.64 billion and growing. A probiotic is defined as a microorganism that survives the digestive process to confer a health benefit on the host, which in this case, is us. The health benefits of probiotics center around diversifying what is known as the microbiome. The microbiome is composed of a huge number of microflora that work together to regulate health, but two of the most focused on in the supplement industry are from two genus, Bifidobacterium and Lactobacillus. For example, John wrote about Bifidobacterium longum in his post about the cognitive benefits of probiotics. If you look at a supplement label closely, you’ll see manufacturers throwing all sorts of strains of Bifidobacterium and Lactobacillus together into the same bottle. Does this make sense? I’m going to take a bit of time here to go over what they are, what they do, and hopefully help you understand where these might best fit into your supplement regimen.
What are Bifidobacterium and Lactobacillus?
Both of these genus are Gram-positive (which just means that they have a thick cell wall made of peptidoglycan) and part of the lactic acid-producing groups, and found to be safe as probiotic supplements.23 A two-part study showed that the risk of probiotic-associated bacteremia (essentially a condition where the bacteria go to places they shouldn’t, like the blood) was only 0.2%, while a study spanning seven years showed no bacteremia when patients were given a probiotic combination.45 This is the first point that counsels in favor of combining a few strains of probiotics, combinations prevent one strain from becoming dominant and taking over.Bifidobacterium vs Lactobacillus
It’s important to note here that while these Bifidobacterium and Lactobacillus are a major part of the whole, our microbiomes are made up of roughly a thousand different species. While there is no real recipe for a “healthy” microbiome, we do know that balance is the key to a happy and healthy gut.6 With that in mind, what are the respective benefits of these types of bacteria?Benefits of Bifidobacterium
First, to go over some basics: Bifidobacterium is a genus of the bacteria kingdom that reside in the GI (gastrointestinal) tract, vagina and mouth of mammals. They are Gram-positive, use glucose as fuel instead of oxygen (anaerobic), and are usually branched-shaped. Bifidobacterium makes up 25% of adult fecal bacteria and 80% in infants, a phenomenally high number. What separates this genus from the other bacteria is a particular pathway that allows it to ferment carbohydrates. This is beneficial for us because plant and milk carbohydrates are undigestible in their natural form. Fermentation turns these carbs into short chain fatty acids (SCFAs), which is the main energy source for our intestinal cells.78 We also discuss SCFA in our recent post: Can you outrun your gut issues? But aside from providing our bodies with much-needed SCFAs, Bifidocacterium also works to protect us from infections. For instance, B. Infantis was shown to have a broad spectrum of antimicrobial properties to inhibit the growth of pathogens and B. animalis DN-173 010 can adhere to intestinal cells, which keeps invading viruses or bacteria from binding to our epithelial cells.9 Some species from this genus were also found to help stimulate our immune systems: B. longum increases the immunological defense systems in germ-free mice and B. breve YIT4064 enhances IgA-antibodies that are antigen specific for rotavirus, a major cause of acute childhood diarrhea, in mice.9 See my previous blog post to get a refresher on what these mice are: How our gut bacteria can fight tumor growth.Benefits of Lactobacillus
Lactobacillus falls under the phylum Firmicutes, which are characterized by their Gram-positive cell walls and are the only bacteria to contain PanK-II enzymes, which is the first enzyme in the Coenzyme A (CoA) pathway. They are non-spore forming and rod shaped, and use transport functions as a means of survival, as they have difficult synthesizing amino acids and other cellular building blocks. Like Bifidobacterium, Lactobacillus ferments carbohydrates into SCFAs. Both genus are found in the gut and vaginal systems of mammals. Lactobacilli have been used to make dairy products like cheese and yogurt, as they have a high tolerance for low pH conditions, a feature that allows for them to travel through GI tract and survive the abrupt pH changes in the intestinal system. A review of the Lactobacillus genus from Diane M. Citron’s lab at UCLA found commercial uses for the following species from the genus.10Lactobacillus acidophilus is considered to have probiotic characteristics. It is used commercially in many dairy products. Lactobacillus casei including strain Shirota (YIT9029) (Yakult Honsha Co. Ltd Japan) complements the growth of L. acidophilus, a producer of the carbohydrate-digesting enzyme amylase. It is involved in the production and ripening of cheddar cheese and is the dominant species in naturally fermented Sicilian green olives. Lactobacillus brevis, L. fermentum, and L. parabuchneri are the 3 major species of dairy obligate heterofermenters that, when present in cheese during ripening, can influence the flavor and texture of the final product. L. parabuchneri is also used to produce sourdough bread and ferment vegetables. Lactobacillus bulgaricus is used for the production of yogurt. It is also found in other naturally fermented products and is used to preserve milk. It produces bacteriocins, which can be bactericidal in vitro.While both Bifidobacterium and Lactobacilli bacteria share metabolic properties, Lactobacilli have a much higher level of phylogenetic, phenotypic, and ecological diversity and have over 170 recognized species. This diversity has made it difficult to identify new and current species, which makes it even harder for consumers to decide which strain to include in their diets. However, one thing is clear: when choosing a Lactobacillus supplement, try to choose products containing live bacteria. A recent study found that the freeze-drying process led to a loss of viability of Lactobacillus from acids produced by the sugars used as cryoprotectants.11 In one study, researchers found that mice with irritable bowel syndrome had a decrease in severity of disease when given L. acidophilus, specifically they found that the probiotic suppressed the inflammatory cytokines IL-6, TNF-a, IL-1B, and IL-17 in the colon and spleen as well as decreasing the activation of myofibroblasts, which are immune cells that migrate to sites of injury and produce inflammatory cytokines.12
Lactobacillus and Bifidobacterium in the Immune System
As an immunologist, my focus has been on how the immune system works and what happens when something goes awry. It wasn’t until recently that I began to look at how the microbiome affected the outcomes of our experiments and how probiotics could be used to help treat patients with cancer or autoimmune disease. Several studies have also shown benefits for combining Bifidobacterium and Lactobacillus when treating inflammatory bowel diseases. One uncontrolled study showed that B. bifidum Bb12 given with Lactobacillus acidophilus over three weeks doubled the number of peripheral white blood cells with that could engulf and destroy pathogens.1314 Additionally, benefits for patients with the autoimmune disease Crohn’s or Ulcerative Colitis were reported in a double-blind, placebo-controlled trial, with a combination of eight probiotics, including B. longum, B. breve, and B. infantis prevented relapse of chronic pouchitis after remission.1516 UC patients also seemed to have better symptom control when given a supplement with a mixture of Lactobacilli La-5 and Bifidobacterium Bb-12 as well as fermented milk with live B. breve, B. bifidum and L. acidophilus YIT 0168.171819