The gut and brain start out as best friends from the very beginning of your life. These massive organs start out inside the fetus as one clump of teeming new life. Then this group of cells splits almost exactly in half. One segment travels to the gut to become the intestinal tract and the other migrates to the head to become your brain.

Both these organs have protective barrier systems that surround and shield them. In the gut this protective barrier is called the semi-permeable gut wall. It is made up of a single layer of epithelial cells combined with magical mucus. In the brain it’s called the blood-brain barrier system. Both barrier systems are designed to protect you, your blood and central nervous system from bacteria, toxins, and other pathogens, from gaining entry and causing havoc and disease throughout your body.

A team from Harvard, led by Chenghua Gu, an associate professor of neurobiology at Harvard Medical School, has figured out what protects these barrier systems: omega-3 fatty acids, most commonly found in fish oils. These fatty acids, already well-recognized for their anti-inflammatory and estrogen and heart protective actions, play a critical role in preserving the integrity of these barrier systems, particularly in the brain.

Omega-3 fatty acids, docosahexaenoic acid, DHA, and eicosapentaenoic, EPA, keep your brain, like the bubble boy in the Seinfeld routine, free from potential poisons.

Published in the May 3rd issue of Neuron, Gu’s team gave the first molecular explanation for how these barrier mechanisms remain protective and defensive against potential toxins.

The transport of unhealthy bacteria, toxins, or other potential bad players across these barrier systems is called “transcytosis.” Transcytosis is when potentially noxious molecules are able to cross through cell walls in the form of vesicles, or small bubbles. The more these vesicles form, the more harmful molecules can leak across. The less number of these vesicles, the less bad stuff gets through.

Blocking formation of these vesicles or bubbles is how the barrier systems are protected. Omega-3 fatty acids are the molecules that come to the rescue. Healthy local fats inside your blood cells and nervous system inhibit formation of these transporting vesicles. The healthier the balance between omega-3 fatty acids and other lipids inside local blood cells, the less harmful toxins can translocate through into your brain or gut tissues, where they can then cause considerable damage.

After every single meal all humans have some amount of transcytosis across the gut wall. Excessive translocation of unhealthy molecules can lead to diverse illnesses. Fish oils help reduce transcytosis at the gut wall as well as your blood-brain barrier.

The blood-brain barrier is composed of a network of cells—endothelial cells that are a type of epithelial cells that line blood vessels in the central nervous system. They stand shoulder-to-shoulder and are connected by tight junctions. These form a barrier that is supposed to prevent nasty molecules from getting into brain tissue. In a 2014 study published in Nature, Gu and his team first showed that a specific gene and the protein it encodes, Mfsd2a, is what is responsible for inhibiting transcytosis.

Well, here’s the deal: fish oils boost the production of this protective gene. This is food being a powerful medicine.

To keep healthy, you want less transcytosis across your brain and gut barriers. Fish protects you. Eating at least two healthy fish meals a week and/or taking fish oil supplements (always check the label to make sure you are getting high levels of EPA and DHA and not mostly unknown fats) both help.

Remember to avoid gelatin capsules. I had Dr. Stephanie Seneff, a senior MIT scientist, on my radio show. She explained that glyphosate from Roundup, sprayed on non-organic animal feed, and becomes concentrated inside gelatin capsules. It paralyzes your microbiome so you want to avoid as much exposure as possible. Purchase nutraceuticals that come in cellulose veggie caps or powders, not gelatin.

By eating fish or taking fish supplements, EPA and DHA from the oils become part of your cell membranes. Inside the cell membranes, higher levels of EPA and DHA boost Mfsd2a production. This protects you against transcytosis.

Everyone with leaky brain or gut needs fish oil. Seed oils contain precursors to omega-3’s, but conversion is patchy and varies from person to person, if you can convert them at all.

The three types of omega-3 fatty acids that work inside the human body are:

  1. A-linolenic acid (ALA) (found in plant oils),
  2. Eicosapentaenoic acid (EPA), and
  3. Docosahexaenoic acid (DHA) (both commonly found in marine oils).

Sources of these come from:

  1. Fish, marine algae and phytoplankton
  2. Animal omega-3 EPA and DHA fatty acids come from fish, fish oils, eggs from chickens fed EPA and DHA, squid oils, and krill oil.
  3. Plant oils that are robust in ALA fatty acids are walnut and edible seeds like flax and hemp, but conversion to omega-3’s is not dependable.

Alpha-linolenic acid, the oil found in plants such as seeds and nuts, must be converted into EPA and DHA. But conversions into EPA and DHA are undependable. One review looked at various scientific papers assessing conversion of plant oils into protective omega-3 fatty acids. Seven papers reported that ALA from nut and seed oils was not converted to DHA at all! Three studies showed that ingestion of micro-algae oil led to significant increases in red blood cell and whole blood DHA. One study suggested that “coated” supplements of plant oils gave better conversion rates. Oils from marine algae appear to be particularly promising.

Eating whole foods, in many studies though not all, and often looking at fish oil’s role in other health issues, appears to be more protective than only taking supplements. Whether this is true for transcytosis has not yet been clarified. I recommend both food and supplements. Also, you don’t need to take fish oil supplements every single day for every single week. Several times a week, if you are eating a great diet, and digesting it, should be sufficient. But, if you are healing a specific health problem you may need to take fish oils daily, or multiple times a day. All foods and supplements need to be individualized.

Knowledge is power and omega-3 oils are powerful, too! Brain powerful and protective, that is.

PS: Great intimacy protects your brain, too. Check out for free video on exact do’s and don’t for detox and other gifts, and to buy the book!

Related Blogs


Blood-Brain Barrier Permeability Is Regulated by Lipid Transport-Dependent Suppression of Caveolae-Mediated Transcytosis. Neuron, 2017; 94 (3): 581 DOI: 10.1016/j.neuron.2017.03.043

Bioavailability of omega-3 essential fatty acids from perilla seed oil, PLEAFA March 2003 Volume 68, Issue 3, Pages 207–212

Bioavailability and Potential Uses of Vegetarian Sources of Omega-3 Fatty Acids: A Review of the Literature Critical Reviews in Food Science and Nutrition, Volume 54, 2014 – Issue 5