New research reaffirms the promise of probiotics to ameliorate osteoarthritis pain. But the review left the researchers with more questions than answers. 

The new research, “The Potential Role of Probiotics in the Management of Osteoarthritis Pain: Current Status and Future Propsects,” was published in the journal Current Rheumatology Reports. It was the work of researchers associated with universities and hospitals in Finland, Belgium, India and China. 

In addition, one of the researchers works for Haleon, formerly part of GSK. Haleon manufactures many mass market channel supplements, including the Centrum line of vitamins.  However, the research was funded by a grant from a Finnish university. 

Role of inflammation in OA pain 

The researchers’ goal was to elucidate the current understanding of the mechanism of osteoarthritis (OA) pain and to understand how feedback loops involving the gut microbiome might affect it. 

OA is an insidious problem accounting for more years lived with disability than any other musculoskeletal malady, according to the paper. For many years, the researchers noted, OA was considered to be a mostly or entirely mechanical condition. Cartilage wore out or was damaged by trauma, leading to pain and decreased range of motion and ability to bear weight. 

More recently, however, the role of inflammation in the process has gained greater prominence, the authors noted. 

For example, OA pain is often a side effect of obesity. This was thought of at one time as merely the result of greater load on the joints caused by the excess weight. 

Now, however, “It is possible that the systemic inflammation associated with chronic inflammatory states, such as obesity or certain chronic diseases, promotes local inflammation in joints that ultimately results in OA,” the researchers wrote. 

This line of thinking is not entirely new, the authors noted. The term “gut joint axis” was coined a few years ago to describe the possible interplay between the gut microbiome and joint health. 

While the idea has been recognized as a legitimate field of research, not much has been done yet, the authors noted. 

Data promising, but scarce 

Some promising preclinical work has been conducted, but animal models go only so far in mimicking the human system. After all, humans are the only modern examples of a bipedal animal that walks with its spine upright. 

The researchers found only three clinical studies that assessed the impact of probiotics on OA. 

One of these, however, included 461 patients and ran for six months. A second was also on the large size for supplement ingredient trials, with a group of 67 subjects. 

A third trial was an observational study on a lone patient. It was structured as three blocks of 10 weeks, each investigating a different probiotic and its effect on the patient’s OA knee pain. 

While broad conclusions can’t be drawn from such a trial, the researchers said they included it because the study provided “a methodology that individual practitioners can use in clinical practice to generate practice-based evidence.” 

But, they noted, several studies are ongoing, and the combination of the preclinical results along with the small amount of clinical data indicate the future is bright for this idea. 

“Despite encouraging results, this review highlights the need for more high-quality clinical studies addressing the potential role of probiotics in OA-related pain,” the researchers concluded. “Preclinical animal models only partially mimic the complexity of the human microbiome.” 

Consultant: Paper part of broadening field 

David Keller, industry consultant and owner of Keller Consulting Group, said the horizons of the probiotic field have widened rapidly in recent years. 

“We continue to see that the effects of the microbiome are not limited to the gut but have whole body effects,” he told Natural Products Insider in an email. “Probiotics (and now also pre and postbiotics) have been shown to positively effects many areas of the body, with new studies regularly being published.” 

“While this paper focuses on osteoarthritis (a disease endpoint), it looks at many of the potential mechanistic effects of probiotics, which could help companies better understand how it is working and where there could be potential for claims in non-diseased populations,” Keller added.