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Beware the Trojan Horse

You remember the story of the Trojan Horse, right? It’s about the subterfuge that the Greeks used conquer the city of Troy by leaving a huge wooden horse outside the walls of Troy and then pretending to sail away. The Trojans then pulled their trophy, their “gift horse,” into Troy.  But there were Greek soldiers inside the horse; and the rest, as they say, is history. Or myth, as the case may be. Joanna, my brilliant classics professor daughter, assures me that I’ve got all this right. So it’s right.

As a metaphor, of course, “Trojan Horse” refers to a strategy used to enter an enemy’s securely protected space. The Trojan Horses I want to talk about today are the ones who escape from a “leaky gut” and enter a “leaky brain”(1). 

“Leaky gut” refers to the situation where the intestine becomes more permeable and allows toxic materials and organisms to escape into the bloodstream. This may be a factor in how people develop systemic inflammatory conditions, such as metabolic syndrome(2) and autoimmune diseases(3). 

This inflammation, in turn, makes the blood-brain barrier more permeable so that these toxins, bacteria, and other unwelcome molecules act like Trojan Horses and enter the central nervous system. It’s possible that this phenomenon is even related to neurological disorders (4), such as depression(5) Alzheimer’s disease, and autism spectrum disorder(6). 

So how to keep these tiny unwelcome horses from entering your bloodstream and then your brain? The answer is to do the best you can to keep your gut from being “leaky.” Aside from a genetic predisposition (such as celiac disease), the major factor is the food you eat. You knew I was going to say that, didn’t you? Processed food bad, real food good. The food you eat determines what microbes live in your gut. And those microbes play a huge part in how permeable the intestinal membrane is. Eat your vegetables. Please.



(1)Kim SK. Mechanisms of microbial traversal of the blood–brain barrier. Nat Rev Microbiol 2008; 6(8):625-34.

(2)Fändriks L. Roles of the gut in the metabolic syndrome: an overview. J Intern Med 2017; 281(4):319-36.

(3)Opazo MC et al.Intestinal microbiota influences non-intestinal related autoimmune diseases. Front Microbiol 2018; 9:432.

(4)Sequella L et al. Play in advance against neurodegeneration: exploring enteric glial cells in gut-brain axis during neurodegenerative diseases. Expert Rev Clin Pharmocol 2019; 12(6):555-64.

(5) Simkin DR. Microbiome and mental health, specifically asit relates to adolescents. Curr Psychiatry Rep 2019; 21(9):93. 

(6)Fowlie G et al. The perturbance of microbiome and gut-brain axis in autism spectrum disorders. Int J Mol Sci 2018; 19(8):E2251.