High vitamin A without taking supplements: how is that possible?

First: what is vitamin A?

When we say 'vitamin A,' we are actually talking about a family of molecules. These include retinol, retinal, retinoic acid, and retinyl esters. There are also plant-derived carotenoids, such as beta-carotene, which our body can convert into vitamin A according to its needs. The form most commonly measured in a blood test is serum retinol, and this distinction is important.

Vitamin A does not circulate freely in the blood

Retinol is a fat-soluble molecule, and in order to travel through the plasma, it needs a carrier protein. The main one is called RBP (Retinol-Binding Protein); we can think of it as a taxi: vitamin A binds to this protein and travels through the body. In addition, this complex interacts with another protein called transthyretin. That is why the result of a vitamin A blood test depends not only on how much retinol you have, but also on how it is transported and how it is eliminated.

And here is where an organ that almost nobody talks about comes in: the kidney

The kidney plays a role in the metabolism and elimination of certain forms of the carrier protein RBP. When kidney function declines, some forms of RBP can accumulate in the blood; and since RBP carries retinol, circulating vitamin A concentrations can also rise. This is well documented in patients with chronic kidney failure. That is why, when I find an inexplicably elevated vitamin A level, one of the things I want to know is how kidney function stands: creatinine, glomerular filtration rate, and the overall clinical context.

So, can a high vitamin A level come from the kidney and not from the diet?

Yes, and this is one of the things that surprises patients the most. An elevated serum concentration can exist without the person taking large amounts of vitamin A. This does not mean that any minor kidney impairment automatically produces hypervitaminosis, but it does mean that kidney function is part of the interpretation.

And what about the liver?

It is also fundamental. Vitamin A is fat-soluble, which means the body can store it, and the main storage site is the liver. The liver also plays a role in the storage, mobilization, synthesis of carrier proteins, and metabolism of retinoids. That is why, in the face of a significant vitamin A abnormality, it also makes sense to review liver function, history of liver disease, alcohol consumption, medications, and nutritional status.

But there is a particular nuance here: liver disease does not always produce a high vitamin A level. In certain liver diseases, serum retinol can actually decrease. That is why we cannot apply a simple equation along the lines of 'impaired liver = elevated vitamin A': the whole picture must be interpreted.

What if the result is high because I had the blood test done after eating?

How the analysis is performed can also have an influence. After a meal containing preformed vitamin A, retinyl esters transported in lipoproteins may temporarily circulate in the blood. That is why, when we genuinely want to investigate a possible excess of vitamin A, it may be important to carry out the test in a fasted state, depending on the parameter we are studying. Not all measurements have exactly the same meaning.

Serum retinol has an important limitation

And this is probably the most interesting point. Our body tries to keep blood retinol within a relatively stable range; it is very tightly regulated. That is why the blood level of retinol does not perfectly reflect how much is stored in the liver. A person can accumulate vitamin A over time and still show a serum retinol level that is not especially remarkable; and, conversely, an isolated elevated retinol level does not by itself demonstrate clinical toxicity. That is why we must not diagnose 'hypervitaminosis A' simply because we see a red flag on a lab report.

So, how do we know whether a true excess exists?

First, the clinical history. I ask about everything that might contain vitamin A or retinoids, and this is where many surprises emerge.

'Hidden' supplements

The patient says: 'I don't take vitamin A.' Fair enough. But they are taking a multivitamin, a 'hair' supplement, another 'skin' supplement, cod liver oil, a longevity product, an eye supplement, or an 'immune' supplement. And when we check the labels, several of them contain vitamin A. The patient was not taking a product called 'vitamin A,' but they were adding up vitamin A from three different products. This happens, and that is precisely why you need to review the labels, not just the names of the supplements.

And be careful with cod liver oil

It is not the same as a conventional fish oil. Cod liver oil can provide significant amounts of preformed vitamin A; if it is also combined with other supplements, the total intake can rise considerably without the patient being aware of it.

What about eating liver?

Liver is one of the foods richest in preformed vitamin A, and frequent, substantial consumption can contribute very high amounts. However, a person who does not eat liver, does not take fish liver oil, does not take supplements, and does not use retinoid medications should not develop a markedly elevated level simply from eating one or two eggs a day.

Do eggs contain vitamin A?

Yes. The yolk contains vitamin A, but in normal nutritional amounts. One or two eggs a day are not equivalent to a megadose of retinol. Therefore, when a patient with that kind of diet presents a very elevated value, I look for another explanation before blaming the egg.

What about carrots?

Here lies another myth. Carrots contain beta-carotene, and the body converts beta-carotene into vitamin A in a regulated manner. That is why consuming large amounts of carotenoid-rich vegetables can cause even a yellowish discoloration of the skin called carotenemia, but it does not usually produce the classic toxicity associated with preformed vitamin A. Ingesting plant-derived carotenoids is very different from taking high doses of retinol or retinyl esters.

What about creams containing retinol?

This is another question I am asked frequently. A cosmetic cream containing retinol applied correctly to the skin involves systemic exposure that is very different from ingesting vitamin A. Therefore, the routine cosmetic use of topical retinol is not, under normal circumstances, the first explanation I would look for when faced with a markedly elevated serum vitamin A level. Systemic retinoids are an entirely different matter.

Isotretinoin and other retinoids

Medications such as isotretinoin are derivatives of vitamin A and have systemic pharmacological effects. That is why, when we are assessing a problem related to retinoids, we need to know whether the patient is using oral medication for acne, systemic dermatological treatments, or certain related drugs. Applying a retinol cream is not equivalent to taking an oral retinoid.

What symptoms can true vitamin A toxicity cause?

Chronic hypervitaminosis A can produce symptoms such as dry skin, dry lips, hair loss, muscle or joint pain, headache, fatigue, and liver abnormalities. At very high levels of exposure, other significant problems may also arise. Excess vitamin A is not harmless precisely because it accumulates: unlike many water-soluble vitamins, we cannot easily eliminate any surplus through the urine.

And this is particularly important during pregnancy

Preformed vitamin A and certain retinoids in excess can be teratogenic — that is, they can cause serious abnormalities in fetal development. That is why the doses and sources of vitamin A take on special importance before and during pregnancy, and why systemic retinoids have strict protocols for precisely this reason.

The patient who feels perfectly well and has high vitamin A

What do I do? I do not start by saying 'stop eating eggs.' First, I confirm that the result makes sense.

First question: what is the exact value?

Being slightly above the upper limit is not the same as being two or three times above it. We also need to know the units, the laboratory's reference range, and exactly which analyte has been measured.

Second question: was the patient fasting?

Depending on the type of assessment we wish to carry out, this can be important — especially if we want to evaluate certain circulating forms of vitamin A.

Third question: what supplements is the patient actually taking?

And here I recommend something very simple: bring all the bottles. Do not rely on 'I think it doesn't contain vitamin A.' We read ingredient by ingredient, because vitamin A can appear as retinol, retinyl palmitate, retinyl acetate, 'vitamin A,' or be part of multivitamin blends.

Fourth question: how are the kidneys and liver?

We review, depending on the context, creatinine, glomerular filtration rate, transaminases, GGT, alkaline phosphatase, bilirubin, and other parameters when indicated. Renal insufficiency deserves particular attention because it can clearly elevate circulating retinol and RBP.

Fifth question: are we measuring the right marker?

When there is a genuine suspicion of chronic vitamin A excess, isolated serum retinol may not be sufficient. In selected situations we can consider other measurements, such as fasting retinyl esters: a high proportion of circulating retinyl esters may be more suggestive of hepatic storage saturation and vitamin A excess than a simple isolated retinol. It is not a test that everyone needs, but it explains why 'high vitamin A' is not always a complete diagnosis.

And what about triglycerides and cholesterol?

These can also be relevant for interpreting certain circulating forms. Retinyl esters are transported in lipid particles after intestinal absorption, which is why postprandial status and lipid metabolism can influence some measurements. Once again, we need context.

So, is a high vitamin A level dangerous?

It depends. A slight elevation in a single blood test, without symptoms and without a compatible history, does not automatically equal toxicity. But a persistent, significant elevation associated with symptoms or accompanied by hepatic abnormalities warrants investigation. And while the cause is being clarified, we obviously avoid adding unnecessary vitamin A supplements.

I do not recommend trying to 'lower it' by following strange diets

This is another important point. When the patient sees the red arrow, they start eliminating eggs, dairy, vegetables, fish… everything. No. First we find out why it is elevated. If the problem is a hidden supplement, we remove it; if there is a renal abnormality, we interpret it in that context; if the test needs confirmation, we repeat it correctly; and if there is a true overload, we act on the source.

A blood test should never be interpreted by isolating a single number

This case of vitamin A is a perfect example of something I explain constantly. The laboratory provides us with data; the medical work consists of converting that data into clinical information. A value can be high due to intake, transport, storage, elimination, disease, medication, or even the conditions under which the sample was obtained. That is why a red arrow does not equal a diagnosis.

What I want you to remember

If your vitamin A is elevated and you're thinking 'that's impossible, I don't take vitamin A,' there are several things we need to review. First, confirm what has actually been measured and how elevated it is. Second, review all supplements and medications. Third, assess kidney and liver function. Fourth, find out whether the test was carried out under the right conditions. And fifth, remember that serum retinol does not perfectly reflect the body's vitamin A stores.

I'm Dr. Florian Vallecillo, and if there is one single idea I want to leave you with, it is this: a high vitamin A level does not automatically mean you are eating too much vitamin A. Retinol metabolism depends on the liver, the kidneys, the transport proteins, the storage process, and the chemical form of vitamin A. That is why, when a result seems to make no sense, we do not blame the egg first or immediately start a restrictive diet — we first try to understand the physiology. Because very often the right question is not 'what food do I need to cut out?' but rather 'why do I actually have this marker elevated?'.