Search SAFM

Unsung Immune System Hero: Vitamin A

  Vitamin Who?   In recent years, we haven’t heard much about Vitamin A in the US.  Unfortunately Vitamin A deficiency is internationally profound and widespread. You may have read about efforts to prevent early childhood death from infectious disease in third-world countries (for which Vitamin A has been a tremendous blessing). But otherwise, conventional medicine media has little to say about this critical nutrient. While overt, life-threatening Vitamin A deficiency is rare in our society, most of us are unaware of the impact (and common risk) of having suboptimal Vitamin A.

First of all, it’s important to understand that (like Vitamin D), Vitamin A is both a fat-soluble nutrient and a steroid hormone.  Thus it is no surprise that Vitamin A plays a wide range of key functions in the body. It is especially critical for the ongoing health of surfaces which line the body which are called epithelial cells (e.g. our skin, eyes, respiratory tract, GI tract, urinary tract). It is also crucial for good vision (hence the old adage of eating carrots for healthy eyes), and insufficiency can lead to impaired vision or night blindness (keep this in mind with your older clients in particular). Vitamin A supplementation has also been shown to improve eczema, lower the incidence of kidney stones, protect against the formation of stress-related ulcers, alleviate dry skin or brittle nails, and reduce the incidence of ear infections in children.

I want to shine a light on a a critical function that is often overlooked, however:  Vitamin A plays a major role in immune system strength.  First, a little physiology…  Our immune system functions with a well-tuned symphony of  diverse white blood cell types, all with targeted and critical roles.   Vitamin A reduces the negative effects of effector T cells and thus helps to control inflammation (specifically inflammatory TH-17 cells).  It also increases our T-regulatory cells which  help to balance immune response and prevent auto-immune activation.   Vitamin A is also required for secretory IgA production  – the critical antibodies  that help our immune system to identify friend from foe at the interfaces in our body (e.g. where food meets intestinal villi in the intestines).  It also helps regulate the very inflammatory cytokine IL-17. Insufficient levels can lead to loss of immune tolerance and increased susceptibility to infections, allergies, and auto-immune illness.  Low Vitamin A is often found in diabetics, alcoholics, and those with auto-immune disease such as Crohn’s Disease.

Vitamin D is also critical for immune system regulation, and many people supplement with it in the months when most Americans cannot make any Vitamin D from the sun (in New England, for example, this is from late September through early May).  Even during the summer months in southern states, it will surprise you to learn how many of your clients have insufficient Vitamin D (ideally 50-70 ng/ml).  But here’s something that might really surprise you: Vitamin D and Vitamin A actually bind to the same final cellular receptor in the body. So increased uptake of one (such as Vitamin D in the summer or when your clients are taking a supplement) can cause a relative deficiency in the other, if your clients’ levels aren’t balanced. If you have clients who get sick often or have trouble shaking a cold or “stomach bug”, consider asking them to have both their Vitamin D and Vitamin A levels checked.  Both are simple blood tests, and they are readily available from just about any physician. Make sure you encourage them to ask for their specific data results (not just a letter saying their levels are “fine”). Your clients will want to be in the upper half of the reference range for both.

Why are we deficient? Most multivitamins today include only plant-based precursors to Vitamin A, usually beta carotene. We know clinically that, at best, only 40-60% of beta carotene from plant sources is absorbed. Unfortunately, it’s also estimated that as much as 50% of the population is poor at (or incapable of) converting carotenes to true Vitamin A. Research shows there is extreme genetic variability in our conversion capability. This critical conversion happens in the lining of your intestines and is also dependent on several nutrient co-factors, especially zinc and iron. Thus those with anemia or zinc deficiency (common!) may struggle. Vitamin A conversion will also likely be significantly impaired in your clients if they have gastrointestinal issues such as food allergies/sensitivities, parasite infection, bacterial overgrowth (dysbiosis), digestive enzyme deficiency, gallbladder issues, celiac disease, or fat malabsorption. Complicated GI disorders are a focus area in my client practice, and unfortunately I see these circumstances every day. In addition, conversion of beta carotene to the active form of Vitamin A is regulated directly by T3 thyroid hormone. As we’ve been discussing in our clinical course on Thyroid/Adrenal disorders, we have an epidemic of subclinical hypothyroidism (which is not, by the way, being necessarily treated well with the conventional protocol of synthetic T4-only medications e.g. levothyroxine such as Synthroid).  Many people who take T4-only meds are still deficient in T3 (the only accurate way to check this is to assess specifically their “free T3″ levels).  Unfortunately these same clients are likely to struggle with insufficient Vitamin A.

As you can see, Vitamin A sufficiency can be a challenge!   Another barrier to Vitamin A sufficiency in our culture is the mainstream health media’s inappropriate fear-mongering about saturated-fat-containing foods.  In fact, natural, healthy, nutrient-dense foods such as organic and grass-fed whole eggs, beef, and butter  are excellent sources of fully-formed Vitamin A. And yes, our clients need to eat the egg yolks (that’s where most of the nutrients are!). Vitamin A is also high in oily fish like mackerel.  Beyond food, to boost the immune system (especially if a specific client doesn’t feel the foods above make them feel their best),  I recommend 5000 IU daily of fully-formed vitamin A (i.e. one of the retinoids like retinol palmitate vs. just beta-carotene). Be sure they take it on a full stomach after a fat-containing meal. If your clients struggle with any of the ailments I’ve mentioned, you may want to encourage them to get their  levels tested and try a higher dose of 10,000 IU/day (the tolerable upper intake level recommended by the Institute of Medicine) for a few months if their levels are not optimal.

Contrary to popular myth, true Vitamin A toxicity is extremely uncommon and has been found to occur in adults only at intake levels over 50,000 to 100,000 IU/day (pregnant women should not take more than 10,000 IU/day).  I suspect isolated “toxicity” incidents may actually be caused by an imbalance of Vitamin A and D that I mentioned earlier, especially given the high incidence of Vitamin D deficiency in most parts of the US.  Common early signs of too much Vitamin A include itchy skin, headaches, bone pain, and nausea which resolve quickly after reducing intake. In summary, realize that your clients do not have to get a cold or an upper respiratory infection every year!  You can help them to be wildly-satisifed by feeling well year-round.   To boost their immune system overall, my recommendation for most is a combination of Vitamin D (minimum 2000 IU/day D3 is safe for almost all), Vitamin A from food or supplement, a probiotic, and zinc (20mg/day is safe for all – don’t get the carbonate form) supplementation along with a diet rich in Vitamin C and K in the form of dark leafy green vegetables.

Vitamin A is yet another example of a nutrient that, in our culture, is not often clinically “deficient (and hence would be dismissed by most physicians) but can indeed be commonly “insufficient” (meaning there is room for improvement).   The difference between these two terms can make the critical distinction for your clients between simply surviving and truly thriving.

19 Questions for “Unsung Immune System Hero: Vitamin A”

  1. 9
    Claudia says:

    It seems like the true problem is not so much the deficiency per se, but the inability of the body to absorb it, due to insufficiency of other co-factors, like it often happens in biology.

    • 9.1
      SAFM Team says:

      Yes, indeed, there can be plenty of Vit A around but if the body is limited by genetic factors, or gut issues or by lack of co-factors necessary for absorption, Vit A won’t be efficiently converted to it’s active form and absorbed.

  2. 8
    Tammy Valta says:

    Is there any liquid form of Vit A you would recommend for teen who are not swallowing supplements?

  3. 7
    Lisa Jackson says:

    How much vitamin A would you recommend for acute acne and for how long?

    • 7.1
      SAFM Team says:

      I would seek Vitamin A labwork and respond accordingly; excessive Vitamin A might exacerbate existing acne, so I do think caution is merited. In the absence of data, I would likely focus on increasing intake via foods (e.g. liver, egg yolks), but if not, one might do a trial in this case of 5000 IU/day for a month (ensuring sufficient D and K2 first!) and gauge effect. Keep in mind too that zinc is needed to support Vitamin A absorption, so this may be a point of interconnectedness in many individuals (given the role of zinc also in optimizing immune function and androgen balance).

  4. 6
    David Sander says:

    Thank you for this balanced and technical report on Vitamin A. As an older runner of 63, I started reading the recent research finding on vitamin D3 years ago and worked up to taking 10,000 IU daily. This resulted in my not tripping and falling during runs along with other improvements.
    I later noticed that my skin scrapes were not healing well, being still pink months afterward and I started taking 4000 IU of retinol in cod liver oil for this. My skin gradually improved and now actually looks younger and my lower back pain soreness after running started to improve and improved further with an increase to 8000 IU of retinol. Long story short…After trials with higher doses I settled on 27,000 IU as optimal (higher doses gave dry eyes). The 10,000 IU D3 to 27,000 A ratio seems to work for me (I’m 95 kg) but it would be even better to see research supporting this. Is there any good science you have found on this question of the ratio?

    • 6.1
      SAFM Team says:

      Good for you, David! Indeed, I am not aware of any research on the optimal balance. And even if there were, we don’t have a way of taking account of the other sources (vs. just supplements)… Some individuals take in copious fully-formed vitamin A from foods (e.g. liver, egg yolks). Others don’t but are champion converters of beta carotene to Vitamin A. Some make final form Vitamin D readily, wile others don’t. Some have stronger Vitamin D receptor sensitivity while others don’t (and genetics can play a role here). It’s a very rich, complex mix, and there is no substitute for getting educated, following your intuition, exploring your own experience, and paying close attention to how your body responds. I would just keep in mind that Vitamin K is the third member of this trio too. If you are supplementing with the others at these high levels, I personally would consider some additional K2 (in the MK-7 or MK4 form). This is an exploratory write-up that I think you may enjoy: . Be well!

    • 6.2
      SAFM Team says:

      Indeed, I certainly would agree with you that there is confusion and much more to learn about the benefits of MK-4 vs. MK-7 supplementation and optimal choices for various purposes. I didn’t share the article to imply this was “the right answer” at all, just to share more information and food for thought with regard to speculation on optimal ratios. Clearly you are well read on the topic, and most of all, I appreciate your deep review of the research and skeptical eye.

  5. 5
    Dawn Parker says:

    I have case of documented severe vitamin A deficiency (via labs), despite animal intake and trial of Green Pastures fermented cod liver oil AND trial of Vital Proteins grass fed beef liver capsules, (labs show vitamin A continuing to decline despite these). How long do you recommend supplementing with actual vitamin A/retinyl palmitate before re-testing? Hashimoto’s is part of the picture, inhibiting conversion from beta carotene, but near normal antibodies and ideal thyroid labs, including Free T4, Free T3 and Reverse T3.

    • 5.1
      SAFM Team says:

      Indeed, there may be poor conversion, as you well state. However, given the ongoing intake of these sources of Vitamin A, I would consider the likelihood of fat malabsorption in the intestines (perhaps combined with fat maldigestion e.g. low lipase secondary to poor pancreatic output and/or low bile output usually secondary to congestion in the bile duct system). And indeed a hypothyroid state can contribute to suboptimal digestive secretions in a circular, debilitating fashion. For you personally, this seems unlikely given your thyroid panel results (though the impact can be erratic). You certainly could supplement with retinol palmitate for six weeks (what I would choose as well – toward the goal of prioritizing getting the body in an optimal place, especially if there are B/L chronic autoimmune activation concerns) and then retest to help differentiate between gut dysfunction and poor conversion.

  6. 4


    Are there any foods (coffee included, drugs, or lifestyle habits that wipe out Vitamin A in the body?


    • 4.1
      SAFM Team says:

      Well, first of all, I would reference explicit items implied by the article above. Excessive Vitamin D intake can deplete Vitamin A. Chronic stress (high cortisol) that impairs conversion of T4 to T3 thyroid hormone is also a harmful choice in this vein given its potential impact on poor beta carotene conversion; choices that create physiological stress (e.g. eating of one’s food sensitivities, ongoing insufficient sleep) would do the same. Having poor fat absorption in the gut will also have an impact (e.g. those without a gallbladder, persistent diarrhea, overuse of laxatives). There are only a few drugs of known impact e.g. . I am not aware of any study explicitly looking at the impact of coffee, though a negative effect has not been found wrt other fat-soluble vitamins; of course, if coffee causes diarrhea or excessive transit time, then the vitamin may be negatively affected simply due to malabsorption.

  7. 3
    Dawn says:

    Thank you. I have an account with Pure Encapsulations so that recommendation is perfect. I am not familiar with vitamin A acetate. How does that differ from retinyl palmitate?

    • 3.1
      SAFM Team says:

      Two different forms of Vitamin A. And semantics. Retinyl (or “retinol” or “Vitamin A”) palmitate or retinyl acetate. Chemically, they are ester forms of retinol. Pure retinol is easily oxidized and needs a stabilizer for supplement manufacture. This may be of interest to you for further learning: .

  8. 2
    Dawn Parker says:

    Do you have a specific vitamin A supplement to recommend? Most of my clients have autoimmunity (especially Hashimoto’s) and digestive issues so ones that would be good for those situations would be helpful.

    • 2.1
      SAFM Team says:

      There are many excellent choices. I have often recommended Pure Encapsulations Vitamin A plus Carotenoids: This gives a 5000 IU dose of fully-formed Vitamin A along with other key antioxidant carotenoids (good for countering all oxidative stress, though particularly helpful for eye health). Especially for those with digestion/absorption limitations (and those with chronic AI also often have sensitivities/allergies), I am a fan of Pure Encapsulations and Thorne Research. Two brands certified gluten-free and which contain no binders or fillers at all in any of their products. Typically more expensive but worth it, given you want to be confident that the nutrient in question is actually being absorbed and put to good use!

  9. 1

    Tracy, I am just wondering why on the EWG skindeep website, when you type retinol, they consider it toxic. Isn’t retinol Vitamin A. It is an 8 in toxicity there. Thanks.

    • 1.1
      SAFM says:

      Yes, I can see how this might be confusing. While Vitamin A within the body is a necessary vitamin, the article correctly points out that excessive Vitamin A (as is true with every fat-soluble vitamin) can be harmful. It also highlights that Vitamin A used on the skin (topically, as opposed to ingested internally) and then exposed to sunlight is vulnerable to free-radical damage (which can be harmful). Again, this is true of many nutrients and is why most good-quality supplements will have antioxidants added to their formulations to protect the raw ingredients from the damaging effects of sunlight, air, and oxygen – even when designed for internal consumption. Most high-quality skin creams I have seen including retinol for purposes of skin healing will specifically warn the consumer not to expose themselves to direct sunlight right afterward. I think this is good guidance.

Ask a Question

Practitioner clarification questions are welcome! Please do not post personal case inquiries.