Firmicutes bacteria can help maintain bone mass, study suggests

A recent study involving 684 Chinese adults has uncovered a significant connection between gut microbiota, aging, and bone health, particularly in relation to osteoporosis, a condition that weakens bones and increases the risk of fractures.

The research, conducted by BGI Genomics' Institute of Intelligent Medical Research (IIMR) and partner institutions, was published in npj | Metabolic Health and Disease, an open-access journal published by Nature Portfolio, earlier in May. The journal focuses on all aspects of metabolism, including basic mechanisms, metabolic diseases, and clinical studies related to diagnostics and interventions.

The study emphasized how gut bacteria may influence bone mineral density (BMD), offering insights into microbiota-based strategies for the prevention and treatment of osteoporosis.

Microbiota composition affects BMD

Osteoporosis is a growing concern, especially among aging populations, where it contributes to a higher risk of fractures and reduced quality of life. Factors such as aging, menopause, and poor nutrition are widely known to affect bone health. This study delves into the unclear role of gut bacteria in regulating BMD, specifically examining how certain gut bacteria may influence bone health.

One of the key discoveries in this study was the difference in how gut microbiota composition affects age-related BMD decline. Researchers found that individuals with a Bacteroides-dominant microbiome (ETB) experienced a much steeper decline in BMD with age compared to those with a Prevotella-dominant microbiome (ETP). This pattern was consistent across both men and women. The study also noted that age was associated with a higher risk of reduced BMD (osteopenia or osteoporosis) in individuals with ETB compared to those with ETP.

Microbiome promotes bone health

The study revealed significant associations between microbial pathways related to L-arginine biosynthesis and butyrate production with higher BMD. L-arginine is an amino acid that is essential for nitric oxide (NO) production, which has been shown to inhibit osteoclast-mediated bone resorption, ultimately promoting bone health. These findings suggest that enhancing the production of L-arginine and butyrate through gut bacteria could be an important strategy in maintaining bone density, particularly in aging individuals.

The study suggests that Firmicutes bacteria, including those from the Lachnospiraceae family, can help maintain bone mass. This is achieved through the modulation of the host's metabolic and inflammatory status. The same metabolites that help regulate metabolism, like butyrate, also have a positive impact on bone health by reducing chronic inflammation, a key factor in bone degradation.

Bone health is also deeply influenced by the microbiome. Our study suggests that Firmicutes bacteria, including those from the Lachnospiraceae family, can help maintain bone mass. This is achieved through the modulation of the host's metabolic and inflammatory status. The same metabolites that help regulate metabolism, like butyrate, also have a positive impact on bone health by reducing chronic inflammation, a key factor in bone degradation.

Butyrate, in particular, has been shown to influence osteoclasts (cells responsible for bone resorption) and osteoblasts (cells responsible for bone formation). It helps to modulate the immune system, promoting a healthy balance between bone formation and resorption. Chronic inflammation, often driven by an imbalance in gut bacteria, has been linked to diseases like osteoporosis, but butyrate can help to counteract this effect by lowering the levels of inflammatory markers in the body.

While the study didn't find significant differences in gut microbiota diversity between individuals with osteoporosis, osteopenia, and normal bone density, it did show that specific gut bacteria were closely linked to higher BMD. These findings suggest that promoting the growth of butyrate-producing bacteria or enhancing L-arginine production could be an effective strategy for maintaining bone mass and preventing osteoporosis. Furthermore, the study indicates that a deeper understanding of gut microbiota profiles could help personalize osteoporosis treatments.

The findings open the door to potential microbiome-based interventions for osteoporosis prevention and treatment. By focusing on specific bacteria that produce butyrate and L-arginine, researchers may uncover new ways to boost bone strength, especially in those at higher risk of bone loss.

Stratifying individuals based on their gut microbiota enterotype could lead to more personalized approaches to managing bone health, ensuring that treatments are tailored to the specific microbial composition of each individual, offering new hope for maintaining bone health as we age.