Within the vast ecosystem of the human large intestine resides Eubacterium hallii, a species of bacteria gaining attention from the scientific community. It is an anaerobic bacterium, meaning it thrives in oxygen-free environments, and lives commensally within our gut without causing harm. While its presence has been known for some time, recent research has begun to illuminate its specific contributions to maintaining gut health.
A Key Producer of Butyrate
Eubacterium hallii is a proficient producer of butyrate, a short-chain fatty acid (SCFA). Butyrate is the primary energy source for colonocytes, the cells that line the colon, and is vital for the health of the intestinal wall. While many gut bacteria produce butyrate from dietary fibers, E. hallii has a valuable metabolic capability. It synthesizes butyrate not only from simple sugars but also by using metabolic byproducts from other bacteria.
This process is known as cross-feeding. Other beneficial microbes, such as certain species of Bifidobacterium, ferment complex carbohydrates and produce lactate and acetate. E. hallii takes up this lactate and acetate from the gut environment and uses them as building blocks to generate butyrate. This function makes it an important member of the gut microbiota for maintaining metabolic balance, as it helps regulate the intestinal environment by consuming lactate, which can be detrimental in high concentrations.
Influence on Metabolism and Energy Balance
The influence of Eubacterium hallii extends beyond the colon, affecting the body’s overall metabolism. The butyrate it produces can be absorbed into the bloodstream, where it circulates and interacts with various tissues, including the liver, muscle, and fat cells. This systemic reach allows it to play a part in regulating the body’s energy balance, primarily by improving how the body handles sugar.
Research has shown a link between the presence of this microbe and enhanced insulin sensitivity. Clinical studies involving individuals with metabolic syndrome demonstrated that supplementation with E. hallii (also classified as Anaerobutyricum soehngenii) can lead to better glycemic control. For instance, participants showed reductions in HbA1c, a marker of long-term blood sugar levels, and improved glucose tolerance after a meal.
E. hallii also influences the production of gut hormones. Its presence can stimulate intestinal L-cells to secrete more glucagon-like peptide-1 (GLP-1). This hormone is known to enhance insulin secretion, slow down stomach emptying, and promote a feeling of fullness. Through these mechanisms, E. hallii contributes to a healthier metabolic profile.
Strengthening the Gut Barrier
The butyrate produced by Eubacterium hallii helps fortify the intestinal barrier. This barrier is a complex layer of cells and mucus that separates the contents of the gut from the rest of the body, controlling what gets absorbed. The integrity of this barrier is maintained by “tight junctions,” which are protein structures that seal the space between adjacent colonocytes.
Butyrate strengthens these tight junctions by enhancing the expression of proteins like claudin-1, which tightens the seals between cells. It also helps suppress proteins like claudin-2, which are known to form pores that increase the permeability of the gut barrier. This dual action helps reduce intestinal permeability, often referred to as “leaky gut.”
A robust intestinal barrier prevents bacteria, toxins, and undigested food particles from leaking into the bloodstream. Such leakage can trigger an immune response and lead to systemic inflammation. By helping to maintain the gut barrier, the activity of E. hallii is a significant contributor to this protective function.
Dietary Factors That Influence Growth
Encouraging the growth of Eubacterium hallii does not involve consuming the bacterium itself, as it is not available as a commercial probiotic. Instead, its abundance can be supported by consuming specific types of dietary fibers known as prebiotics. E. hallii does not directly ferment complex fibers but relies on a collaborative relationship with other gut microbes that do.
Prebiotics like fructans and resistant starch travel undigested to the colon. There, they become a food source for primary fermenters like Bifidobacterium, which break them down and release lactate and acetate. E. hallii then uses these compounds to produce butyrate. By incorporating a variety of these fiber-rich foods, one can support the entire microbial food chain that benefits butyrate producers.
Good sources of these prebiotics include:
- Onions
- Garlic
- Leeks
- Asparagus
- Chicory root
- Cooked and cooled potatoes
- Green bananas
- Legumes
- Whole grains