Vitamin A, Leaky Gut and The Immune System


The interplay between intestinal permeability and different disease states is a major interest of mine. Naturopaths, Herbalists and wisdom traditions including, among others, Ayurveda and Chinese Medicine have known that the different body systems influence and affect each other in intricate ways.

Science is finally catching up to this thinking and many traditional healing concepts are being ‘proven’ in the scientific research.

Today we will be exploring the impact that vitamin A has on leaky gut and the immune system.

This article is part of a long exploration into the world of leaky gut and associated diseases. Further reading would include these articles.

A Quick Vitamin A Primer

First off what is vitamin A?

It is a fat soluble vitamin that influences a whole range of different body processes including among others

  • Cell differentiation
  • Growth factors
  • Immune function

The most important function in relation to this article is vitamin A’s function in supporting the mucous membrane in the digestive tract (1).

Vitamin A comes in a few different varieties. Beta carotene, also known as provitamin A and retinol, known as preformed vitamin A. The carotenoids are potent antioxidants but are less active than retinol (2).

Beta carotene can be converted into a retinoid form. The conversion rate is hotly debated and quite hard to pin down to a number. An interesting point here is that in vitamin A deficiency the conversion from beta carotene to active vitamin A is upregulated. More is converted.   

Retinol, and retinoic acid, are considered the physiologically active form of vitamin A. They have profound effects on the body and influence cell differentiation, development and immune function.

Retinol, and only retinol, makes up the light absorbing units in the retina of the eye. It is required for vision (3).

Theories on Intestinal Permeability and Disease States  

In the past we have covered the connection between different disease states and leaky gut.

Leaky gut has been associated with the progression of different autoimmune disease. A quick summary would take into account three specific factors outlined in this paper.

  1. The genetic susceptibility to an autoimmune disease. This is where many people stop. You might think that having the genes for a particular autoimmune disease is a sure thing. There are a number of other factors that need to present
  2. The trigger. The idea here is that something needs to actually set off the autoimmune progression. This is referred to as an ‘antigen’. Many times it can be bacterial, fungal or viral. Sometimes it may be an undigested food antigen setting off the immune system.
  3. Finally the environmental agent (the trigger) needs to be able to interact, and set off, the immune system. I like to think about it like a chemistry reaction. There needs to be contact between the antigen and the immune system for a reaction to happen.

In this theory leaky gut is required.

In a healthy functioning system the gut barrier keeps these antigens inside the gut. When permeability increases the immune system interacts with these antigens setting off an overactive response (5).

Vitamin A, Leaky Gut and Disease Progression

A recently published review dives deep into vitamin A and leaky gut. Today we will be picking out some important points to discuss.

First off intestinal epithelial cells, forming the gut barrier, is covered by a mucous layer. This layer is crucial for the healthy functioning of the gut. It traps invading microbes preventing inflammation. There are also antimicrobial peptides found in this mucous layer again helping to defend and protect the underlying tissue.

Retinol has been shown to have be inversely correlated with intestinal permeability (7).

Translation – lower serum retinol was associated with increased leaky gut.

The study looked at 30 children’s serum vitamin A. They also tested their intestinal permeability with a lactulose/mannitol test. They found low vitamin A in the children that had high mannitol in their urine, indicating leaky gut.

Now this isn’t concrete data. We need more information to come to solid conclusions.

Another study compared difference in immune function and intestinal permeability in children with suspected low vitamin A. While the intestinal permeability did not change between the group receiving high dose vitamin A therapy and the placebo group there was a significant decrease in parasitic infections, notably Giardia (8).

The conclusion here was that vitamin A supports immune function and defence to Giardia. I would assume we can extend that to other parasitic infections like Blastocystis and Dientamoeba fragilis.

Back to the review.

Vitamin A may improve leaky gut in a number of ways. Much of this is still being worked out. Some is in-vitro (aka test tube) data and some is animal studies. We can’t draw any strong conclusions from this evidence but it does point us in the right direction.

  • Vitamin A has been shown to improve the tight junctions which control what passes from the gut lumen into the body.
  • Vitamin A has an intricate relationship with the gut microbiota. Together they influence the immune function by regulating the B-cell response.
  • Certain gut flora produce acetate, a short chain fatty acid. This in turn pushes B-cells to become IgA producing cells (a top defender in the gut ecosystem). Vitamin A is needed as a signal to make this process happen.
  • Influenced by vitamin A the gut flora can promote a more tolerant immune response by upregulating T regulatory cells. I like to think of these T regulatory cells as the dampener on an overactive immune system.

So we are left with the question as to how vitamin A improves leaky gut? Is it directly through influencing the cellular structures that heal and seal the gut wall or is it by interacting with the beneficial microbes that make up our gut microbiome?

The answer is probably both.

In the words of the authors of the review ‘It is likely that RA exerts protective effects against a leaky gut and, subsequently, autoimmune pathologies through both direct and indirect mechanisms.’

Where Do We Find Vitamin A – Food Sources

This article we are focusing on improving leaky gut and maintaining the gut barrier. As such there is a main focus on the active form of vitamin A. Different forms are found in the foods below (9).

Preformed vitamin A is commonly found in certain animal foods including

  • Liver
  • Eggs
  • Fish

Beta-carotene is found in a number of plant foods, but remember it still has to be converted into the active form to function on the gut wall.

  • Carrots
  • Spinach
  • Broccoli
  • Parsely
  • Sweet potatoes
  • Apricots
  • Peaches

References and Resources

  1. Vitamin A : nutrition, side effects, and supplements
  2. Vitamin A, carotenoids, and retinoids.
  3. Meeting the Vitamin A Requirement: The Efficacy and Importance of ?-Carotene in Animal Species
  4. Alterations in intestinal permeability.
  5. Alterations in intestinal permeability.
  6. Retinoic Acid, Leaky Gut, and Autoimmune Diseases.
  7. Retinol and Retinol-Binding Protein: Gut Integrity and Circulating Immunoglobulins
  8. Effects of vitamin A supplementation on intestinal barrier function, growth, total parasitic, and specific Giardia spp infections in Brazilian children: a prospective randomized, double-blind, placebo-controlled trial.
  9. Meeting the Vitamin A Requirement: The Efficacy and Importance of ?-Carotene in Animal Species
Legal and Affiliate Disclosures: This post may contain affiliate links. That means if you decide to make a purchase through one of these links, I may earn a small commission at no extra cost to you. Learn more here

You may also like


  1. All I can say is “ WOW”! I have a terrible leaky gut. Intolerance to salacylates, oxalates, histamines, amines, and so many others. I have type 1 diabetes for 45 years. I controll it perfectly for the last 6 years ( a1c is 6.4), but I have Coronary artery disease( I think from a previous deficiency of Vitamin k2, which I now supplement), neuropathy and so much more. I leaned if leaky gut 5 years ago and have studied it meticulously ever since. I do EVERYTHING possible to cure it, to no avail. I can’t take biofilm breakers because they interfere with the chemical communication system of not only the “ bad” bacteria, yeast, fungi & viruses in my gut, but the biofilms breakers also interfere with all the good bacteria, viruses, yeast & fungi in my gut. Its Called “ Quorum Sensing”. ( in case you don’t already know). The biofilm breakers cause a malfunction with the electrical system in my heart, I have a RBBB( Right Bundle Branch Block), amd my heart beat slows down to about 20% and it makes me feel like I’m going to die. I can’t function and I have to stay in bed 24/7. It’s awful. I do super concentrated ( gel) chicken bones broth from organic chicken feet, APPLE cider vinegar, and up until recently, 2 tablespoons extra virgin coconut oil everyday. Suddenly I developed a complete intolerance to the coconut oil ( because of the salacylates it contains). I assume that my gut health has decreased once again , and that’s why this is happening. Incidentally , I have to take 1000 mg Question every morning 2 hours before ingesting all these things, do I don’t get the mast cell inflammation and then have a reaction.,It’s all extremely complicated.,My leaky gut comes mainly from taking antibiotics every 3 months of my adult life for one thing or another. I could go on here forever….. Anyways, I enjoyed your article tremendously and I’m going to try taking some vitamin A. The only problem is that I don’t have a lot of good gut bacteria left, and I’m wondering if the vitamin A can be converted and/or uploaded for use, by whatever good microbes I have left in my intestinal tract. Most of all, I’m hoping and praying that the vitamin A can help restore the mucosal lining of my intestinal tract.,Thank you for a great article! I will be following your column from this point forward.

    1. Hi Linda:

      I have some same leaky gut and food sensitivities that you have and also RBBB. My health went downhill in March 2021. I am also homebound trying to get better, I also have mild gastritis. Will be trying glutamine to heal my gut, if possible.

  2. I’m allergic to aspirin. I never understood the sac in other foods, etc. I’ve been pushing all the fruits and vegetables due to long covid. I’m wondering now, how much of this long covid is due to this sensitivity. Oh boy, that would be a game changer! The only reason I found this is because my morning smoothie knocked me out. Full of black grapes and sweet cherries., among other things. Seeds nuts powders and protein!

Leave a Reply

Your email address will not be published. Required fields are marked *

Hello. Add your message here.