Can bone health be improved through microbiota manipulation?

Bones which have been damaged by diet-induced obesity could be brought back to health through the use of prebiotics and probiotics to alter the gut microbiota, say researchers from Chiang Mai University in Thailand.

Long-term consumption of a high-fat and high-sugar diet can cause a gut microbiota imbalance, which is linked to conditions such as type 2 diabetes and osteoporosis.

Obesity is known to cause cardiovascular disorders, arthritis and osteoporosis, among other conditions, as well as metabolic bone disorders.

A healthy gut microbiota is key

The role of gut microbiota has been extensively researched in recent years and it has been demonstrated that healthy gut microbiota can stimulate proper development of the immune system, provide humans with extra energy and protect against invading pathogens.

However, gut dysbiosis – an imbalance of the resident gut microbiota population instigated by a long-term high-fat and high-sugar diet – results in an increased inflammatory tone both locally and systematically which is a factor to bone loss.

The report’s authors looked at all relevant, published, up-to-date findings on the subject of obesity, gut microbiota and jaw bone density, in order to establish a relationship between the three.

They found that the recent data did suggest that diet-induced obesity has a negative impact on bone health possibly via the alteration of gut microbiota and host immune status, and that manipulating gut microbiota could improve bone health.

The majority of the studies looked at were animal studies, largely using rats or mice as test subjects.

Previous studies were found to have demonstrated that gut microbiota can regulate bone mass in mice and that the administration of probiotics and prebiotics can slash the risk of bone loss.

Furthermore, the role of prebiotics on long bone health in growing animals has also been reported.

One study reviewed in the report, involved treating growing rats with the prebiotic galacto-oligosaccharide (GOS).

This was found to increase the number of Bifidobacterium spp. and modify the gut microenvironment, enhancing calcium and magnesium usage, thus improving bone mechanical properties.

Other studies showed that after daily consumption of prebiotics, calcium and magnesium are absorbed and retained more in the body, leading to improved bone health.

Saccharomyces cerevisiae, a brewer’s yeast, and Lactobacillus brevis CD2, a probiotic, have also been shown to improve bone health.

It is suggested that probotic organisms could be of benefit to jaw bone health due to the local regulation of the host immune response.

Human data is needed

The authors conclude their report by saying that no firm conclusions can be made just yet, and more studies are needed to better understand the role of gut microbiota.

“Due to a lack of available supportive data, new well-designed experiments and or/randomised control clinical trial data would definitely benefit this field,” ​said Sathima Eaimworawuthikul and her team.

Although recent data suggests that gut microbiota plays an important role in bone health, the majority of studies have focused on rats and mice, rather than human participants.

“Understanding more of the underlying mechanisms of how gut microbiota plays a role in ‘cafeteria-diet-induced’ obesity and its related pathology, including jaw bone density loss, is essential for the field of dental research”.​

The authors also concluded that alterations of gut microbiota by antibiotics seem to affect not only gut microbiota but also metabolism.