Evidence Based This post has 17 references
4.4 /5

The Importance of Real Vitamin A (Retinol)

Written by Joe Cohen, BS | Last updated:

SelfHacked has the strictest sourcing guidelines in the health industry and we almost exclusively link to medically peer-reviewed studies, usually on PubMed. We believe that the most accurate information is found directly in the scientific source.

We are dedicated to providing the most scientifically valid, unbiased, and comprehensive information on any given topic.

Our team comprises of trained MDs, PhDs, pharmacists, qualified scientists, and certified health and wellness specialists.

All of our content is written by scientists and people with a strong science background.

Our science team is put through the strictest vetting process in the health industry and we often reject applicants who have written articles for many of the largest health websites that are deemed trustworthy. Our science team must pass long technical science tests, difficult logical reasoning and reading comprehension tests. They are continually monitored by our internal peer-review process and if we see anyone making material science errors, we don't let them write for us again.

Our goal is to not have a single piece of inaccurate information on this website. If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please leave a comment or contact us at [email protected]

Note that each number in parentheses [1, 2, 3, etc.] is a clickable link to peer-reviewed scientific studies. A plus sign next to the number “[1+, 2+, etc...]” means that the information is found within the full scientific study rather than the abstract.

Vitamin A and its byproducts are very important in the body. It could be more of utilization problem or another issue, but retinoic acid and its interactions is a major link in inflammation/disease that holds promise for people.

What is Vitamin A?

Vitamin A and its byproducts are very important in the body.

Whether supplementation would help these people I can’t know. It could be more of utilization problem or another issue, but retinoic acid and its interactions is a major link in inflammation/disease that holds promise for people.

Overview of Health Benefits

Vitamin A is crucial for your brain, immune system, skin, eyes, teeth, bones and for the formation of hormones.

This is one reason why people with chronic inflammation without fail have skin problems.

Vitamin A protects our eyes and skin from UV damage, so it will allow you to get UV and limit skin cancer risk [1].

1) It Is Important For Vitamin D and Your Thyroid Hormones to Work Properly

Vitamin A/Retinol is crucial in activating Retinoid X Receptors (RXR), which is required for PPAR activation (DHA can also activate RXR) [2].

Vitamin A is also crucial in activating Retinoic Acid Receptors (RAR).

Both RAR and RXR are crucial DNA binding proteins (transcription factors), which are needed for genetic expression. RXR is needed to activate the vitamin D receptor (VDR) and the Thyroid Hormone Receptor (THR).

In simple English, this means if you’re deficient in vitamin A you can take all the vitamin D you want and it won’t make that much of a difference because you need adequate vitamin A to make these work properly.

Vitamin D absolutely needs RXR in order to get the benefits from it and Thyroid hormones need RXR to work effectively.

See below how you need Vitamin D Receptor (VDR) to combine with Retinoid X Receptor (RXR) to result in gene expression. Therefore, you need adequate retinoic acid (a breakdown product of retinol) and vitamin D3 for these to function.


We also make pregnenolone from LDL cholesterol and use free T3 and Vitamin A. So low pregnenolone could indicate a vitamin A inadequacy.

If you are popping your vitamin D pills (or thyroid hormones) and it’s not working for you then try to add some real vitamin A/Retinol (upper level=10,000 IU daily) and see how you feel. Vitamin D might not work for you anyway (it’s better for Th1 dominant), but vitamin A will make it more likely to work for you.

2) The Immune System

Vitamin A increases your Th2 immune system and decreases Th1 and Th17. It’s especially important for the gut immune system.

Vitamin A has other important immune functions and may help you even if you’re Th2 dominant, but it will be less likely to help you than a Th1 dominant person such as myself.

However, if you are Th1 dominant and have low PPARs, you want to make sure your diet includes real vitamin A.

Vitamin A/RXR is crucial for inducing oral tolerance to proteins and it increases Tregs.

See image:

nri3299-f1 Retinol
Source: http://www.nature.com/nri/journal/v12/n10/fig_tab/nri3299_F1.html

3) Adrenal Fatigue

Vitamin A-deficient animals have lower adrenal hormone production [3].

Another study shows that Vitamin A deficient rats had excess cortisol and expressed a hyper cortisol response. When they were given vitamin A their cortisol normalized [4].

I’ve mentioned in my adrenal fatigue post that abnormal production of cortisol doesn’t indicate your adrenal glands are broken. It could be cortisol is abnormal because of low or dysregulated vitamin A.

4) Vitamin A and Weight

Vitamin A might benefit obesity by increasing UCP1 in mice, which increases heat loss/fat burning. But studies in humans haven’t had the same results [5].

5) The Brain

Vitamin A/Retinol plays a central role in increasing neuroplasticity and neurogenesis.

It’s critical to our hippocampus and hypothalamus, which controls memory and wakefulness, respectively [6].

Indeed, vitamin A is important for long-term potentiation (LTP), which is important to form memories [7].

Vitamin A deficiency causes a circadian dysrhythmia, which in turn results in cognitive dysfunction [8].

6) The Circadian Rhythm

Here’s a simple way to think about the circadian rhythm. The body has thousands of processes going on at any given moment. Many of these processes function better in concert with other processes – just like in a symphony, where different sounds work better with other sounds.

These processes have a certain rhythm or flow. The body conducts this orchestra with ‘clock genes’. When they get expressed, it happens all over the body, in a synchronous way.

When I disrupt my circadian rhythm, I notice increased inflammation, oxidative stress and my cognitive function go down. This happens in people whose circadian rhythm isn’t functioning well [9].

Vitamin A is critical to have a normal circadian rhythm and Animals fed a Vitamin A (retinol) deficient diet have a circadian rhythm that doesn’t work in synchrony [8].

When Vitamin A causes a circadian dysrhythmia it likely results in cognitive dysfunction [8].

Specifically, the deficient diet caused an altered rhythm of antioxidant production by our body (Glutathione, catalase, GPx) and BDNF. This results in suboptimal cognitive performance [10, 11, 12].

The rhythms of these antioxidant enzymes are important because in some parts of the day we do better with more internal antioxidants, while at other times we do better with less.

Vitamin A-deficient animals also had reduced periods of wakefulness and energy expenditure (locomotor activity) [11].

In addition to being important for daily rhythms, retinoic acid is also important for seasonal rhythms [6].

7) Blood Glucose

Vitamin A is essential for the beta-cell function in the pancreas, which is responsible for insulin release. Its deficiency leads to excess glucose in the blood [13, 14].

summary_of_actions_of_retinoids1330402609269 Retinol

The Bad

Vitamin A does compete with vitamin D and K2 and studies show higher vitamin A is associated with lower bone density [15].

Scientists believe the relationship is causal. My own experiments with vitamin A support this, as I find that when I take vitamin A supplements, I have a higher need for K2 supplements (evidenced by gums feeling weak and sensitive and bones feeling less sturdy).

How to Obtain Adequate Vitamin A

I used to think of nutrients in terms of the RDA. I don’t anymore. I think of it in terms of an individual’s biology and if taking more of a certain nutrient can balance their physiology better. The question should be if you can benefit from more (or less) of it, not if you’re getting the RDA.

For the past 5 years, I was afraid to take vitamin A because a study was done with beta-carotene supplements that showed it increased lung cancer risk. I also read reports that showed vitamin A deficiency in the population was rare.

I didn’t have the experience or the necessary knowledge to understand that deficiency and inadequacy are different.

I still don’t think deficiency is a problem as much as some environmental factors – perhaps lack of sunlight or circadian dysregulation – is not allowing us to utilize it fully.

If we got the sun, wore red Glasses at night and took care of our circadian rhythm, it should fix this part.

I still recommend you consume foods like Cod liver, regular liver or supplement with Vitamin A/Retinol.

I recommend first experimenting with a higher dosage and seeing how you feel – say 3,000iu. Then cut back to taking 2000iu daily. If you buy 8000iu, you can take it once every four days. Make sure to take extra K2 and D3.

Vitamin A is especially important if you’re Th1 dominant and have low PPARy. Experiment and see if you notice a difference.

1) Vegan Diets

Vegan or vegetarian diets can result in not getting enough vitamin A.

Chris Masterjohn followed a vegan diet and found his health went south. He was very thin and had chronic inflammation – indicative of low PPARs and Th1 dominance. He realized that he was deficient in real vitamin A and felt better by eating liver, the richest source of retinol. He was so enamored with vitamin A that he studied this subject for his Ph.D.

Vitamin A might be one of those nutrients that you can get enough of in a vegan diet if you’ve got the genetic predisposition for high conversion of beta-carotene to retinol or an anti-inflammatory/Th2 immune profile.

However, it’s also possible that vegans are affected, but they don’t notice it.

2) Alcohol Depletes Vitamin A

See how alcohol depletes vitamin A:

images Retinol

Signs of Vitamin-A Inadequacy

Well, these are signs that something about RXR or RAR isn’t working, and vitamin A deficiency is one possible cause.

Genes and Reduced Conversion of Beta-Carotene to Retinol

It’s important to know if you’ve got genes that cause reduced conversion of beta-carotene, because if you do then you definitely need to supplement if you’re on a vegan diet.

The BCMO1 gene (rs12934922 and rs7501331) is known to influence the conversion of beta-carotene to vitamin A [16].

In test tubes, when cells have one T in both genes, they have a reduced conversion activity of beta-carotene by 57%.

Females carrying the T variant of rs7501331 had a 32% lower ability to convert Beta-carotene.

Those carrying at least one T in two genes (rs12934922 and rs7501331) show a 69% lower ability to convert Beta-carotene into retinyl esters.

For rs7501331, 56% of the population has CC, 39% has CT and 5% has TT. If you’ve got CT or TT, you should make sure to get real vitamin A (especially TT).

rs12934922 also converts beta-carotene to retinol. T is the ‘bad’ allele. 38% of the population has AA, 40% has AT, and 22% has TT [17].

Bottom line:

If you’ve got one T in rs7501331 then you should try to get some real vitamin A.

If you’ve TT in rs7501331 then you really need to get real vitamin A.

If you’ve got a T in both genes, then you also need to really get real vitamin A.

If you’ve got one T in rs12934922, I wouldn’t worry. If you’ve got TT in rs12934922 then you should get real vitamin A, but it’s not as significant as rs7501331.

Buy Supplements

Is Vitamin A Right For You?

If you’re unsure about which vitamins you need more or less of, check out our Vitamin DNA Wellness Report. This report tells you if you’re genetically more or less predisposed to have a vitamin deficiency. We also give personalized recommendations to fix the deficiency when they occur.

SelfDecode is a sister company of SelfHacked. This section contains sponsored links, which means that we may receive a small percentage of profit from your purchase, while the price remains the same to you. The proceeds from your purchase support our research and work. Thank you for your support.

About the Author

Joe Cohen, BS

Joe Cohen, BS

As a kid, Joe suffered from inflammation, brain fog, fatigue, digestive problems, mood and other issues that were poorly understood in both conventional and alternative medicine. Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers. Joe is a thriving entrepreneur, author and speaker. He is the CEO and founder of SelfDecode. His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.


1 Star2 Stars3 Stars4 Stars5 Stars
(24 votes, average: 4.42 out of 5)

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

Leave a Reply

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

This site uses Akismet to reduce spam. Learn how your comment data is processed.