How does RLT help?
Red light therapy (RLT) has a bidirectional regulatory effect on bacteria. This therapy can promote bacterial proliferation or inhibit bacterial growth, depending on the wavelength and dose of RLT and the type of bacteria. This bidirectional regulation of RLT on bacteria makes it possible to improve the imbalance of the gut flora, which is commonly seen in people with metabolic disorders (i.e. obesity, diabetes, etc.) and neurodegenerative diseases (i.e., Alzheimer’s and Parkinson’s diseases).
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Recent studies have shown that the intestinal flora is involved in the occurrence and development of Alzheimer’s disease (AD) through a variety of pathways. Therefore, intestinal flora modulation is now being considered as a new target for the treatment of AD. The intestinal flora mainly affects the occurrence of AD through the nervous system, the endocrine system, metabolism, and immunity. In some animal and human studies, researchers have attempted to regulate the intestinal flora to prevent and treat AD.
The intestinal flora of patients with AD is in an unbalanced state, with a decrease in beneficial flora and an increase in harmful flora, which leads to the consequential imbalance of inflammation and immunity and eventually induces or aggravates AD. PBM may be useful for regulating the imbalance of intestinal flora in AD.
Amyloid plaques, tau phosphorylation, and neuroinflammation are the main pathological changes of AD. In research conducted on AD mice that utilized RLT to the gut, it was found that mice in the RLT groups showed amyloid plaque elimination, p-tau reduction, and microglia proliferation. In addition, the RLT intervention resulted in a large number of proteins up- or downregulated in the hippocampus of AD mice (the hippocampus is responsible for functions such as storage conversion and orientation in long-term memory).
There has been an increasing understanding of the link between the gut microbiome, the enteric nervous system and a number of diseases, such as kidney disease, liver disease and cardiovascular disease. Acknowledgement of the importance of the gut–brain axis has increased the recognition of the link between microbiome balance and brain function. It is appreciated that some bacteria that compose the gut microbiome are associated with a range of behavioral dysfunctions and neurodegenerative diseases. This is especially true in Parkinson’s disease (PD).
For example, dysbiosis of the gut microbiome can reduce the number of short chain fatty acid (SCFA) producing bacteria, which in turn increases local inflammatory signaling. Reduction in SCFA production, reduced gastrointestinal functional and anatomical integrity and a consequent increase in the movement of bacterial metabolites (e.g., lipopolysaccharide) across the gut wall are all features of PD, resulting in increased inflammation.
Previous research has demonstrated that RLT treatment applied to the abdomen of mice can lead to a beneficial change in the microbiome. The changes realized in the gut are reflected as a change in the Firmicutes to Bacteroidetes (F:B) ratio. It is frequently reported that a higher ratio is characteristic of poorer gut health and is associated with obesity and an increased inflammatory start and aging.
To date, four non-pharmacotherapeutic interventions have been suggested to slow the progression of PD via manipulation of the microbiome, which include diet, pro- and prebiotics, antibiotics and fecal microbiota transplant. Based on recent research, RLT is a potential novel fifth intervention and may complement new and existing treatment strategies. As a potential therapy, RLT would ideally be commenced as early as possible in the disease trajectory, before severe reduction or complete elimination of beneficial bacteria from the microbiome (including medications) and may best be combined with diet, pre- and probiotics or fecal microbiota transplant to restore microbiome genera.
Crohn's disease and ulcerative colitis (UC) are the main forms of inflammatory bowel disease (IBD). IBD remains as a multifactorial disease, explaining the current difficulty of treatment. UC is a complex disease that possibly comes from an inadequate immune response in genetically susceptible individuals. This is a result of an intimate interaction between environmental factors and enteric immune system, which contribute to inflammatory acute crises, which become chronic when they are not controlled. UC is characterized by continuous inflammation in the large intestine wall, reaching the mucosa and submucosa.
The current treatment for UC includes four drug classes: aminosalicylates, steroids, immunomodulators, and biological therapies that act on inflammatory mediators using antibodies. However, in addition to not being effective in all patients, these therapies present many side effects limiting their usefulness.
Recent research on mice with UC utilizing near-infrared LED therapy inhibited colitis-induced gross lesions in the colon highlighting a drastic improvement of tissue damage. Therefore, suggesting the therapeutic, anti-inflammatory and protective potential of red light therapy for ulcerative colitis.
What does the research show?
“We confirmed that the gut flora-targeted PBM treated Alzheimer’s disease by eliminating Aβ plaques and inhibiting neuroinflammation and tau phosphorylation. The diversity and abundance of gut flora changed after long-term PBM irradiation.” (1)
“We have seen changes in the microbiome of Parkinson’s patients after a 12-week treatment regimen with PBM. Specifically, the F:B ratio, which is often interpreted as a proxy for gut health, improved for the majority of participants with PBM treatment.” (2)
“In conclusion, gut flora-targeted PBM provides a new possible non-invasive prevention and treatment method for the treatment of Alzheimer’s disease (AD), and provides a new hope for AD patients.” (3)
“There was functional improvement as observed by inhibition of colitis-induced intestinal transit delay as well as anatomical and inflammatory improvements as observed by inhibition of colitis-induced colon edema, intestinal dimensions alterations, myeloperoxidase activity and cellular intestinal wall infiltration. At the molecular levels, we observed that (near-infrared) LED therapy…inhibited colitis-induced pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) production.” (4)
**While the current scientific research seems to indicate many positive benefits of RLT in relation to fat loss, there is still an appreciable necessity for more extensive research to be conducted in this area, including double-blind RCT (randomized controlled trials), to provide a more comprehensive, robust overview that will further elucidate the optimal parameters and appropriate uses of RLT, which will ultimately lead the most safe and efficacious uses for individuals attempting to improve gut health.
(2) Bicknell, Brian et al. “Microbiome Changes in Humans with Parkinson's Disease after Photobiomodulation Therapy: A Retrospective Study.” Journal of personalized medicine vol. 12,1 49. 5 Jan. 2022, doi:10.3390/jpm12010049
(3) Chen, Qianqian et al. “Gut flora-targeted photobiomodulation therapy improves senile dementia in an Aß-induced Alzheimer's disease animal model.” Journal of photochemistry and photobiology. B, Biologyvol. 216 (2021): 112152. doi:10.1016/j.jphotobiol.2021.112152
(4) Belém, Mônica O et al. “Light-emitting diodes at 940nm attenuate colitis-induced inflammatory process in mice.” Journal of photochemistry and photobiology. B, Biologyvol. 162 (2016): 367-373. doi:10.1016/j.jphotobiol.2016.07.008