Vitamin A, cod liver oil and retinol: separating myths from facts

Vitamin A, cod liver oil and retinol: separating myths from facts

There’s a growing buzz online about the potential “toxicity” of vitamin A – especially cod liver oil. If you’ve found yourself second-guessing whether to include it in your health routine, you’re not alone. At Supporting Balance, we often hear from people who are confused, overwhelmed, or flat-out scared after reading or listening to influencers who warn against vitamin A altogether.

Let’s cut through the noise.

Retinol – the active form of vitamin A found in foods like grassfed butter, free ranged/pastured eggs, beef liver and cod liver oil – is essential for many critical processes in the body. When used in an informed way, it can be a powerful ally for immune health, thyroid balance, hormone support, and more.

This article walks through the key science-backed reasons why retinol deserves a spot in your nutrient toolkit, particularly when you’re working to rebuild your health from the ground up.

What is retinol, and why is it important?

Retinol is a type of preformed vitamin A, meaning it’s ready for the body to use immediately – unlike beta-carotene, which has to be converted into active vitamin A. Some people have genetic or metabolic difficulties with this conversion, which makes getting true vitamin A from food sources even more critical.

Vitamin A is involved in:

• Immune system regulation
• Vision and eye health
• Skin repair and cell turnover
• Reproductive hormone balance
• Thyroid hormone function
• Copper and iron metabolism (more on this below)

While it’s true that vitamin A is a fat-soluble vitamin and can become toxic at very high doses over long periods, the fear around moderate dietary intake or the use of high-quality cod liver oil is often exaggerated.

Retinol and hormone health

One of the lesser-known roles of retinol is in the conversion of thyroid hormones. Specifically, vitamin A supports the conversion of T4 (inactive thyroid hormone) into T3 (active thyroid hormone). This is essential for energy production, metabolism, mood, and overall hormonal balance.

Vitamin A also helps regulate the hypothalamic-pituitary axis – the signalling system that manages your stress response and reproductive hormones. In women, low vitamin A status has been linked to poor egg quality, irregular cycles, and reduced fertility.

You can’t make vitamin D without retinol and magnesium

One of the most overlooked facts about vitamin A is that your body can’t make vitamin D from sunlight unless you also have enough retinol (vitamin A) and magnesium.

I repeat, your body can’t make vitamin d from sunlight unless you also have enough retinol and magnesium

These two nutrients are critical cofactors in the body’s ability to convert UVB rays into usable vitamin D.

This means that if you’re low in retinol or magnesium (or both – which is very common), your skin may not be able to complete that conversion process efficiently, no matter how much sun exposure you get. It’s one reason why some people are out in the sun every day and still show up “low” in vitamin D on a blood test.

Here’s where it gets even more important: supplementing with synthetic vitamin D (like cholecalciferol) doesn’t solve the real problem. In fact, it can further deplete your body’s retinol stores, creating an even bigger imbalance over time.

So if you’re worried about low vitamin D levels, the answer might not be “more vitamin D” – it might be to replenish what your body needs to make its own, starting with whole-food sources of retinol and magnesium.

Retinol and copper for optimal health:

It’s not just about how much copper you have – it’s how you use it

Retinol (the active form of vitamin A) does more than just support your immune system and hormones – it also plays a key role in how your body handles copper.

Your body needs a special protein called ceruloplasmin to move copper around and use it safely. Ceruloplasmin also helps with things like managing iron and protecting your cells from damage. But here’s the catch: your body can’t make enough usable ceruloplasmin without retinol.

Think of retinol like the “on switch” that helps your body activate this important copper-carrying protein.

If your body can’t make enough working ceruloplasmin, copper can end up in the wrong places or not get used properly – leading to fatigue, mood issues, inflammation, and more.

So if you’ve been told you have “high copper” or are “copper toxic”, or even just if your copper blood test results are confusing, it might not be about how much copper you have – it might be about how well your body is able to use it, and that’s where retinol makes a huge difference.

The science: what the research tells us

Beyond its roles in immune function and thyroid regulation, retinol (preformed vitamin A) is essential for copper metabolism, particularly in the activation of ceruloplasmin – the primary copper-carrying protein in the blood.

Ceruloplasmin not only transports copper but also exhibits antioxidant properties and plays a role in iron metabolism. However, for ceruloplasmin to function effectively, it must be properly synthesised and activated – a process that depends on adequate levels of retinol.

Research has demonstrated that retinoic acid, a metabolite of retinol, can induce the synthesis of ceruloplasmin. For example, a study published in The Journal of Nutrition found that administering 13-cis retinoic acid to rats significantly increased ceruloplasmin activity within 24 hours, with levels remaining elevated for several days (full text here).

Furthermore, in more recent research exploring genetic copper disorders like Wilson’s disease, retinoids were shown to restore ceruloplasmin secretion in liver cells and alleviate oxidative stress. This study, published in Human Molecular Genetics, offers additional support for the role of retinol in healthy copper transport and metabolism (read the study here).

This connection underscores the importance of retinol in maintaining copper homeostasis. Without sufficient retinol, the body may struggle to produce functional ceruloplasmin, potentially leading to copper imbalance and related health challenges.

What about toxicity?

The idea that vitamin A is inherently dangerous often comes from confusion between synthetic, isolated forms (such as those found in some supplements or fortified foods) and whole-food sources like liver or high-quality cod liver oil.

Most of the toxicity concerns in the literature relate to chronic overdosing at extreme levels, or to the use of synthetic retinoids in medications (like Accutane). This is vastly different from using moderate amounts of real-food-based vitamin A as part of a supportive health plan.

When taken alongside key cofactors like magnesium and copper, retinol tends to work synergistically rather than harmfully.

TL;DR – A non-technical summary

• Retinol (real vitamin A) is crucial for hormone health, immune regulation, and energy.
• It’s especially important for activating ceruloplasmin, a key protein that helps your body use copper properly.
• This matters because copper is needed for iron regulation, antioxidant defence, and enzyme activity.
• You don’t need to fear vitamin A in natural food sources – what matters is the context, your individual needs, and getting a balance of cofactors.

You can work with us one-on-one, or explore our growing collection of educational resources, recipes, and guides inside our wellness library.

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