Why Vitamin A Deserves a Second Look
Vitamin A is one of the body’s most vital yet misunderstood nutrients. Best known for its role in supporting clear vision, strong immunity, reproductive health, and cellular integrity, it influences nearly every system in the body — from how we see in dim light to how our cells grow, repair, and communicate.
Despite its far-reaching importance, vitamin A rarely gets the same attention as other nutrients, such as vitamins D, C, and the B vitamins. Yet deficiency remains surprisingly common, even in developed countries.
Vitamin A: A Complicated Nutrient
Adding to the confusion is the question of which form of vitamin A is best. Synthetic forms of vitamin A differ significantly from their natural counterparts. While most supplements and fortified foods rely on retinyl palmitate, a synthetic ester of vitamin A, this form poses a greater risk of toxicity than whole-food, preformed retinol.
Retinol — the active form of vitamin A that the body can use immediately — is the safest and most reliable form, yet intake is often low in modern diets. Meanwhile, beta-carotene, the plant-based precursor to vitamin A, may not be as efficient or reliable a source as many believe.
At Formula IQ, we take this difference seriously. This article explores how to optimize your vitamin A intake to support immunity, vision, gut health, and overall nutrient bioavailability. Let’s take a closer look at the powerful role of vitamin A in its natural retinol form.
What Is Vitamin A and What Does It Do?
Vitamin A is not a single nutrient—but rather a group of fat-soluble compounds known collectively as retinoids (including retinol, retinal, retinyl esters) [1]. These compounds can be consumed in their active, “preformed” state as retinol and retinyl esters from animal foods, or as provitamin-A carotenoids (such as β-carotene from plants), which the body converts into active forms [2].
Core Physiological Roles: What does Vitamin A Do?
Here are some of the principal functions vitamin A serves in the body:
Vitamin A for Better Vision: One of vitamin A's best-known roles is in the visual system. For example, retinal (an oxidised form of retinol) binds opsin to form rhodopsin in the rod cells of the retina, enabling night vision and dim-light adaptation [3].
Vitamin A: A Key Player in Your Body's Defenses
Vitamin A, sometimes called the "anti-infection" vitamin, is a powerful nutrient that acts as a general orchestrator of your body's defense system. It helps build and maintain strong barriers against germs and ensures your immune cells are in the right place to fight off invaders [4]
Vitamin A Builds and Maintains Body Barriers
The surface linings of your body, like those of your gut, lungs, eyes, and urinary tract, are critical protective barriers between you and the outside world. These barriers produce mucus, which serves dual roles – it’s an active site for the immune system defense, and provides moisture and lubrication to its respective organs.
Vitamin A is essential for maintaining the mucosal layers at these barriers.. Without enough of it, these protective layers can dry out and break down, making it much easier for infections to take hold [5].
Vitamin A Directs the Immune Troops
Beyond supporting protective barriers, vitamin A plays a hands-on role in managing your immune function:
Guiding Cells Home: It helps "train" and guide specific immune cells (lymphocytes, including T and B cells) to travel to the mucosal linings where they are most needed to fight off invaders [6].
Producing Protective Shields (Antibodies): Vitamin A supports the production of a specific antibody, IgA (immunoglobulin A). These antibodies are secreted into your mucus layers, acting as tiny shields that bind to harmful invaders and prevent them from attaching to your body's cells [7].
Managing the Response: Vitamin A helps balance the immune response, ensuring the body can fight infections effectively without causing excessive inflammation.. It influences key "messenger" chemicals in the immune system called cytokines, helping to prevent an overreaction that can damage healthy tissue [6].
Supporting Frontline Defenders: It supports the development and function of innate immune cells, such as macrophages and neutrophils, which are the first responders that engulf and kill invading microorganisms [8].
In short, having enough vitamin A helps several factors within your immune system run smoothly, making you less likely to get sick and helping you recover faster when you do
Vitamin A in Growth, cellular differentiation & reproduction:
The key to vitamin A's function in growth, differentiation, and reproduction lies in its ability to directly influence which genes in a cell are turned "on" or "off," essentially acting like a hormonal signal [9].
This control of gene expression is fundamental to essential life processes, including healthy growth, cell differentiation into specialized tissues, and proper reproductive function [10, 11]. By binding to specific receptors within the cell nucleus, vitamin A ensures our cells receive the correct instructions for life and development.
This same function makes vitamin A the gatekeeper of vitamin D bioavailability. The Vitamin D receptor (VDR) cannot function on its own [12]. For vitamin D to initiate its functions, the VDR must team up with the Retinoid X Receptor (RXR), which binds vitamin A derivatives [13]. They form a complex that then binds to DNA, allowing vitamin D to carry out its functions. This means that adequate vitamin A status is vital for optimal vitamin D signaling and performance.
Metabolism & Balance: The Importance of Dosage
Vitamin A is a fat-soluble nutrient, which means the body can store it in the liver and fatty tissues for future use. Unlike water-soluble vitamins (such as C or B), it isn’t easily excreted in urine. This makes balance especially important — both too little and too much can cause problems [14].
When Vitamin A Is Too Low
A lack of vitamin A can lead to a wide range of issues. These include:
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night blindness
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Frequent infections and poor immune function
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Dry or weakened mucosal barriers
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impaired growth and reproduction [15].
In developing countries, vitamin A deficiency remains a leading cause of preventable blindness and increased infection rates in children.
When Vitamin A Is Too High
On the flip side, taking too much preformed vitamin A, especially in synthetic or fortified supplement form, can lead to toxicity (called hypervitaminosis A). Symptoms may include:
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Headache
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Dizziness
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Nausea
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blurred vision
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bone pain
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Liver damage in severe cases
These effects are far more common with high-dose synthetic vitamin A than with natural, whole-food forms like cod liver oil and liver [16]. Studies in South Africa assessed children who consume animal liver at levels exceeding the RDA and potentially the tolerable upper limit of vitamin A, yet often do not show signs of hypervitaminosis A [17].
How the Body Maintains Balance
The body has a built-in protection mechanism to help regulate vitamin A levels. It uses retinol-binding proteins to regulate the amount of circulating vitamin A and to store the rest in specialized liver cells until needed [18]. These feedback mechanisms allow your body to maintain vitamin A balance even when intake varies.
This system works best when vitamin A comes from natural, food-based sources, as isolated synthetic vitamin A can override the system [19].
Common Questions About Vitamin A
What is vitamin A good for?
Vitamin A is one of the most multi-purpose nutrients in the human body. It's best known for supporting vision, particularly night vision. Without enough vitamin A, the eyes do not properly form rhodopsin and struggle to adapt to darkness, which is why night blindness is one of the earliest signs of deficiency.
Vitamin A is essential for a well-regulated immune system. It helps maintain the health of your body’s barrier tissues—like the gut, lungs, and sinuses—while also guiding immune cells to the places they’re needed most. It supports the production of IgA antibodies, which guard mucosal surfaces from pathogens.
It is also vital for cellular growth, tissue repair, and reproductive health. It influences which genes inside your cells get turned on or off, helping direct cell differentiation throughout the body. This makes vitamin A essential for healthy skin, normal fetal development, and proper reproductive function in both men and women.
Which foods are highest in vitamin A?
The best sources of vitamin A are animal-based foods that provide preformed retinol. The highest concentrations are found in liver (especially beef, chicken, and cod liver), egg yolks, butter, full-fat dairy, and fish eggs.
Plants contain provitamin A carotenoids, like beta-carotene, found in carrots, sweet potatoes, spinach, kale, and red/orange vegetables. These must be converted into retinol, but conversion varies widely between individuals and is often inefficient, making animal-based retinol a more dependable way to meet vitamin A needs.
What happens if I take too much vitamin A?
Vitamin A toxicity, or hypervitaminosis A, can occur from taking too much synthetic vitamin A in supplement form. Symptoms can include headache, nausea, dizziness, blurred vision, bone pain, and, in severe cases, liver damage, as this is where vitamin A is stored.
Toxicity from whole-food sources is unlikely. The body has built-in mechanisms to regulate the absorption of vitamin A from food sources. Even populations that consume large amounts of liver do not typically show signs of vitamin A excess. True toxicity from food would require extremely high liver consumption, or, in the off chance of consuming polar bear liver, which contains unusually high levels of vitamin A.
In normal dietary amounts, whole-food vitamin A is safe, well-regulated, and far less likely to cause toxicity than high-dose synthetic supplements.
Is beta-carotene the same as vitamin A?
Beta-carotene is not the same as vitamin A. It is a provitamin A carotenoid—a precursor that the body must convert into retinol, which is the active form of vitamin A that your cells can use.
This conversion is often slow and inefficient. Genetics, thyroid function, gut health, nutrient status (especially zinc and iron), and overall diet all affect how well you convert beta-carotene to retinol. Some people convert very little, even when eating plenty of colorful vegetables.
Because of this, beta-carotene-rich foods like carrots and sweet potatoes are valuable, but they are not a sole reliable source of active vitamin A. Preformed retinol from animal foods or whole-food supplements like cod liver oil is the most dependable way to meet vitamin A needs.
Should I take vitamin A supplements?
Always consult with your healthcare provider to determine whether supplementation is right for you.
Whether you need a vitamin A supplement depends on your diet, health status, and genetics. Many people fall short if they rarely eat foods like liver, egg yolks, full-fat dairy, or cod liver oil, or if they have poor carotenoid conversion. In these cases, supplementation can help maintain healthy vision, immune function, skin integrity, and vitamin D signaling.
However, not all vitamin A supplements are the same. Synthetic forms carry a higher risk of toxicity because they bypass the body’s natural regulation. Whole-food sources of preformed retinol, such as cod liver oil, are better tolerated and far less likely to cause excess buildup.
A high-quality, naturally occurring source like Formula IQ’s Cod Liver IQ provides whole-food-based vitamin A in the same form your body is designed to use, along with vitamin D and omega-3s that support absorption and balance. For most people, a whole-food approach is the safest and most effective way to achieve adequate vitamin A intake.
What’s the difference between retinol and retinyl palmitate?
Retinol is the active form of vitamin A. It’s the bioavailable form your body uses for vision, immunity, cell growth, and hormone-like signaling. When you get vitamin A from whole-food sources like liver or cod liver oil, you’re getting retinol or retinyl esters that your body can readily convert into retinol as needed.
Retinyl palmitate is a synthetic, esterified form of vitamin A commonly used in fortified foods and supplements. It must be converted into retinol before the body can use it. Because it is more water-soluble and less tightly regulated, it carries a higher risk of toxicity when taken in excess.
Whole-food retinol is handled by the body with built-in safeguards, while synthetic retinyl palmitate bypasses part of this natural control. This is why food-based sources are generally safer, better regulated, and more bioavailable than synthetic vitamin A.
Is cod liver oil a good source of vitamin A?
Yes, cod liver oil is one of the best natural sources of vitamin A. It provides preformed retinol, the bioavailable form that your cells can immediately use.. Unlike plant-based carotenoids, it doesn’t require conversion, making it a reliable way to maintain healthy vitamin A levels.
Cod liver oil is also unique because it naturally contains vitamin D and omega-3 fatty acids. These nutrients work together to support immune balance, reduce inflammation, and improve the absorption and utilization of fat-soluble vitamins.
However, not all cod liver oils are equal. Many commercial products are heat-processed and then fortified with synthetic vitamin A and D, altering their nutrient profile and increasing the risk of toxicity. Formula IQ’s Cod Liver IQ preserves the naturally occurring vitamins A and D through a gentle, proprietary extraction process—making it a superior, whole-food source of bioavailable retinol.
Why Fortified Cod Liver Oil Falls Short, and Why Whole-Food Cod Liver Oil Is Better
Many commercial cod liver oils are heat-processed, which destroys much of the naturally occurring vitamin A, vitamin D, and delicate omega-3 fatty acids. To compensate, manufacturers often add synthetic retinyl palmitate and vitamin D₂ or D₃ back into the oil. The result is a product that looks like traditional cod liver oil on the label but is, in reality, an artificially fortified supplement rather than a whole-food source.
This fortification alters the natural ratio of vitamin A to vitamin D and introduces synthetic compounds that the body handles differently than food-based retinol and D3. Many consumers understandably think they’re getting the same nutrient-dense cod liver oil that nourished earlier generations, but sadly, many modern products bear little resemblance to real, ancestral cod liver oil.
Formula IQ’s Cod Liver IQ is fundamentally different. Instead of high-heat processing, we employ a proprietary extraction method that does not expose these delicate nutrients to high heat, preserving the fragile, naturally occurring vitamins A and D found in fresh cod liver. There’s no synthetic fortification—just the highest concentration of naturally occurring vitamin A, naturally occurring vitamin D, and wild-caught omega-3s – as nature intended.
Vitamin A and D help regulate immune function and maintain healthy tissues, while omega-3 fatty acids (EPA and DHA) reduce inflammation and enhance absorption of fat-soluble vitamins. This synergy is what makes true whole-food cod liver oil uniquely effective—and why Cod Liver IQ delivers a superior nutritional profile compared to processed, fortified alternatives.
The Bottom Line
Vitamin A is one of the most essential nutrients for vision, immunity, gut health, reproduction, and overall cellular function. But getting the right form, in the right balance, matters just as much as getting enough.
Whole-food retinol from cod liver oil is more reliable, safer, and more synergistic than synthetic forms or plant-based carotenoids. And when paired naturally with vitamin D and omega-3s, its benefits extend even further.
Most modern cod liver oils compromise this natural synergy through high-heat processing and synthetic fortification. Formula IQ’s Cod Liver IQ preserves the nutrients exactly as nature designed them—pure, potent, and bioavailable—making it one of the most effective ways to support robust health through food-based vitamin A.
Experience the Difference of Real, Whole-Food Vitamin A
If you want a vitamin A supplement that’s safe, naturally balanced, and truly effective, choose the one made without shortcuts - Cod Liver IQ.
