“The Evolving Story of Blastocystis: From Foe to Friend”

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From the summary of the study by Dr. Keszthelyi-a few excerpts:
Background: “Blastocystis is the most common gastrointestinal protist found in humans and animals… At the same, Blastocystis remains one of the most enigmatic gut microbial organisms that has puzzled clinicians for decades… scores of patients with positive stools for Blastocystis have been treated with antimicrobial agents such as metronidazole.”

Methods: “Piperni et al examined 8 of these STs previously described in humans in a global-scale metagenomic exploration in 56,989 individuals from 32 countries. The analysis also included 4590 gut metagenomes from 214 nonhuman species (spanning mammals, reptiles, birds, amphibians, insects, crustaceans, mollusks, nematodes, and metazoans) from 49 public datasets, and paleofeces based on 28 publicly available ancient human gut metagenomic samples with archaeological dating ranging from 3000 BC to the Post-Medieval Age.”

Key findings:

  • “Blastocystis was found in 8190 human stool samples and was fairly common in healthy individuals (16%). Blastocystis was hardly ever found in newborns, suggesting that it is likely acquired later in life and not vertically transmitted”
  • “The 8 human Blastocystis STs were not detected in most of the animal species tested, except for nonhuman primates kept in captivity”
  • “Blastocystis was detected in ancient human samples”
  • “The presence of Blastocystis was positively associated with more favorable cardiometabolic profiles and negatively with obesity. In addition, adherence to a plant-based diet was associated with carriage of Blastocystis.”
  • “In particular, individuals who consumed higher quantities of unprocessed plant-based foods, such as avocados, dried fruits, nuts, seeds, legumes, and cruciferous vegetables, were more likely to be Blastocystis-positive compared with individuals with lower intake of such foods.”
  • Implementing “a 6-month personalized diet intervention study involving 1124 individuals, in which improvements in dietary quality and weight loss were paralleled with an increase in Blastocystis abundance.”

My take: The authors of the Cell study: “our results linking Blastocystis to host health support its non-pathogenic, if not favorable, role.”

Graphical abstract from Cell article