The human gut hosts a wide variety of microbial species including bacteria, viruses, and fungi. Intestinal parasites were also once a typical part of this community; healthy humans played host to these parasites for much of our history until advancements in water quality, hygiene, and medicine largely eliminated them in recent decades. However, there have also been concurrent increases in the rates of bowel disorders that involve autoimmunity or chronic inflammation. As such, some clinicians and scientists began to explore the usefulness of a therapy that involves introducing intestinal worms, or helminths, into patients.
Scientists have now performed a more rigorous evaluation of intestinal worm therapy. This study, which was reported in Nature Communications, showed that intestinal worms have the potential to lower systemic inflammation, but only if they also receive an adequate supply of dietary fiber. A lack of dietary fiber can lead the worms into a hibernation-like phase, and they are no longer beneficial.
In this study, the researchers assessed the impact of intestinal parasites when exposed to varied levels of dietary fiber in a host. The investigators utilized the rat tapeworm Hymenolepis diminuta as a model intestinal parasite; it is often used in studies evaluating parasites, gut microorganisms, the immune system, and their interactions.It is thought to have anti-inflammatory effects on the host, and not pose any threat as a pathogen.
When the tapeworms were exposed to a low-fiber diet, they stayed smaller and did not become sexually mature. There were also genetic changes reflecting significant alterations in developmental, metabolic, and reproductive functions.
"We found that when the diet contains a high proportion of structural fiber, the tapeworm is not only in excellent condition but is also able to induce an anti-inflammatory response in the host. When fiber is lacking, the worm enters an energy-saving state resembling hibernation in mammals, and its anti-inflammatory effect disappears," said senior study author Kateřina Jirků of the Institute of Parasitology at the Biology Center of the Czech Academy of Sciences.
This report also confirmed the results of many other studies that have shown that diets that contain high levels of fiber boost the growth of bacteria that have been linked to a healthy gut. However, diets that were high in fats and sugar, reflecting a Western-style diet, lowered the levels of diversity in the microbiome and boosted the growth of bacteria linked that have been associated with gut dysfunction. The immune response of the host also mirrored these changes.
Inadequate levels of fiber in the diet can disrupt and deplete healthy gut microbes, which can have cascading effects on other functions and systems including mental health, brain function, and immunity. Imbalances in the gut have been associated with a wide range of health problems like anxiety, bowel disease, and neurodegenerative disorders, for some examples.
While more research will be needed to confirm and expand on these findings, the study has suggested that some intestinal worms could have health benefits, and our gut may be disrupted by their loss.
Sources: Biology Centre of the Czech Academy of Sciences, Nature Communications
