Blastocystis, a single-celled organism that is among the most common pathogenic causes of intestinal infections, can be deadly in those with compromised immune systems, such as HIV patients. However, the parasite is also found in asymptomatic people—largely considered “carriers” for the disease blastocystosis—and has confused scientists debating whether it’s harmful or neutral to humans.
Recent large-scale research, however, has found that this gut bug could have redeeming qualities. It has been found in healthy people’s stool samples and is associated with positive biomarkers and whole-food diets.
Linked to Good Health
In the study, published on July 8 in Cell, researchers examined the microbiomes of more than 56,000 people’s stool samples worldwide. Blastocystis was linked to positive cardiovascular and cardiometabolic markers, including better lipid and glycemic profiles and lower body mass index (BMI).The gut microbiome comprises trillions of microscopic organisms, including bacteria, fungi, viruses, and parasites, representing thousands of species. These microbes help with physiological functions and immune protection, making the community largely symbiotic.
Italy’s University of Trento professor and corresponding author Francesco Asnicar told The Epoch Times that research is essential to determine whether Blastocystis is a “bad guy or not.”
“There were a few things we were not expecting. Doing research is sometimes exciting. Sometimes we find a nice story to tell,” he said. “We should probably start moving to consider Blastocystis from a different perspective.”
Blastocystis is especially interesting because it is a ubiquitous member of the microbiome, meaning it appears in more than 5 percent of the general population of developed countries and between 30 percent and 60 percent of the population of developing countries.
In the Cell study, a lack of Blastocystis was linked to obesity. Conversely, people with Blastocystis in their microbial samples had less visceral fat, lower weight, and better glucose management. The greater the presence of Blastocystis in samples, the more favorable the subjects’ blood sugar and lipid profiles were.
Blastocystis was also associated with better-quality diets that included higher fiber and minimally processed foods.
“Our results offer an improved understanding of the complex interplay between the human gut microbiome, diet, and cardiometabolic diseases involving the currently overlooked Blastocystis species,” the authors wrote.
“In the future, precision nutrition interventions aimed at modifying gut ecology may constitute a viable disease-prevention strategy, and our work suggests that underappreciated non-bacterial taxa can have considerable roles in maintaining and promoting human health.”
At this point, it is unknown whether Blastocystis directly improves health. Its presence, however, is related to better gut health.
Infectiousness of Blastocystis
Blastocystis has historically been associated with the sort of infection you’d want to avoid, blamed for causing symptoms such as diarrhea, abdominal pain, weight loss, constipation, excess gas, and anal itching, according to the U.S. Centers for Disease Control and Prevention (CDC).The infection often shows up in international travelers exposed to Blastocystis in another country or who were exposed to someone who recently traveled, according to Ken Boorom, director of the Blastocystis Research Foundation. The foundation was formed in 2006 by patients and their families to drive research on the parasitic infection and help inform doctors about antimicrobial treatments.
“Some people acquire and clear Blastocystis infection spontaneously without any symptoms, while others experience persistent illness upon exposure,” he told The Epoch Times in an email, adding that people could also be genetically susceptible to the illness.
A Controversial Bug
One article published in Parasitologia noted that the pathogenicity of Blastocystis is controversial, with research unable to pinpoint how transmissible the parasite may be.“Other authors have noted that Blastocystis is directly responsible for gastrointestinal disorders and is ... for a certain type of persistent diarrhea, abdominal pain, and vomiting. In immunocompetent subjects, the presence of Blastocystis is not correlated with gastrointestinal symptoms,” researchers wrote. “Otherwise, immunocompromised subjects (cancer, HIV) seem to be more receptive to the parasite.”
- Touching surfaces contaminated with feces from an infected person or animal
- Drinking water, including swallowing water from pools, lakes, bathtubs, rivers, and springs
- Eating undercooked or raw contaminated food
- Coming into contact with a sick person or animal
- Wash your hands frequently, especially after touching animals and soil and before handling food.
- Wash produce before eating it.
- Don’t use water or food you suspect could be contaminated.
- When traveling abroad, avoid uncooked foods and tap water.
Where Does Blastocystis Come From?
The Cell study noted that Blastocystis is rarely found in newborns, which tells researchers that it’s acquired later in life. They also don’t think it’s the product of a modern microbiome, as they discovered it in stool dated as far back as 595 AD.“It’s not something we see transiently going through the gastrointestinal tract,” Asnicar said, adding that it could be something about specific foods or the gut environment that causes the microbe to take up residence in the gut microbiome. These could be topics for future studies.
The study also determined that the presence and abundance of Blastocystis can be influenced by diet.
In the final stage of the research, 1,124 people participated in a personalized diet program to see what would happen to Blastocystis in their microbiomes before and after significantly improving their food quality.
- Fifty-seven people acquired Blastocystis. This group also ate significantly more dietary fiber and fat but not protein and carbohydrates. They also had more fiber in their diets than those who lost Blastocystis or didn’t experience positive changes in Blastocystis levels.
- Twenty-nine people lost Blastocystis, whereas 323 remained Blastocystis-positive before and after the diet.
- Those who tested positive for Blastocystis at the beginning and end of the study experienced an increased abundance of it.
- Those who tested positive for Blastocystis and improved their diet had the most significant reduction in BMI.
- Those who gained Blastocystis during the trial also experienced an enrichment of other species in their microbiomes, which is associated with better health.
- Those who lost Blastocystis also lost diversity in their microbiomes.
Mechanism Is a Mystery
Now that the association has been found—and because it contradicts evidence that Blastocystis is infectious—Asnicar said researchers still don’t know why the organism seems to cause problems for some people and benefit others.He said it could be a similar tale to that of Escherichia coli (E. coli), which gets a bad rap for causing disease. Yet most E. coli strains are generally commensal—meaning they benefit our gastrointestinal tract.
“We cannot exclude that Blastocystis is there and impacting the community, but if triggered in the wrong way, it can have an inflammatory response. That is true also for bacteria,” Asnicar said. “To answer why, we need to understand: Are there subtypes that could respond with inflammation when triggered, and others that don’t? There is still a lot to uncover.”
While the Cell study examined eight subtypes of Blastocystis with a complete genomic sequence that can be profiled, other subtypes exist. However, no data exist to categorize and study them. Asnicar noted that subtypes can have many different species, and even species can have different strains.
Another possible explanation for Blastocystis’ mechanism could be that another microbe—not Blastocystis—is actually responsible for infection, he added.
“If someone experienced diarrhea, abdominal pain, or anything associated with Blastocystis in general and goes to the doctor and gets tested for infection, one out of five will test positive for Blastocystis,” Asnicar said.
Proceeding With Caution
Despite the positive light shed on Blastocystis, the new study also noted that it’s too risky to acquire the parasite intentionally.“Direct artificial administration of Blastocystis has never been attempted and presents ... potential clinical risks, especially in immunocompromised hosts, but pilot studies in animal models could start addressing the causal link with host health,” the authors wrote.
Boorom offered words of caution about such a strategy.
“As far as intentionally consuming Blastocystis to improve health, it’s not clear that an observational study can show this, especially since Blastocystis consumption is related to vegetable intake,” he said, adding that studies have shown that contaminated vegetables are a source of infection.
“Other studies have shown that children with Giardia (a parasite that causes diarrhea, stomach cramps, bloating, and nausea) are more healthy, as well. But we also know that exposing populations to Giardia will result in illness in a portion of that population, and in some individuals, that can be debilitating.”
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