Vitamin A: The Silent Deficiency That Colorful Vegetables Don’t Always Fix

by Laurent Glatz – for Athletic Carnivore

Deficiency almost never shouts. It doesn’t always come with an alarm, sharp pain, or dramatic diagnosis. More often, it begins with subtle signals: dry skin, persistent fatigue, reduced night vision, weakened immunity, irritated mucous membranes, poor recovery, and unstable mood. The body doesn’t collapse all at once. It gradually scales back its functions.

Vitamin A perfectly illustrates this gray zone. On paper, many people believe they consume enough because they eat carrots, sweet potatoes, spinach, or colorful vegetables. But biology doesn’t read nutrition labels like software. It asks a more precise question: is it active vitamin A, or just a precursor your body must convert?

This difference changes everything.

Active Retinol vs. Beta-Carotene

In animal foods, vitamin A is present in a preformed state, notably as retinol and its esters. This form is directly usable by the body. It’s mainly found in liver, eggs, certain high-fat dairy products, fatty fish, and animal tissues.

In plants, it’s not retinol. It’s provitamin carotenoids, primarily beta-carotene. These molecules can be used to produce active vitamin A, but only after enzymatic conversion, notably via the BCO1 enzyme in the intestine. This conversion is highly variable.

Here lies the modern mistake. People add up micrograms of beta-carotene as if they automatically equal retinol. In reality, the conversion efficiency depends on genetics, gut health, zinc status, thyroid function, presence of fats in the meal, inflammatory state, age, and even overall metabolic context.

For some individuals, conversion is adequate. For others, it’s poor. And for a portion of the population, certain genetic variants drastically reduce the ability to convert beta-carotene into usable retinol.

The Trap of “I Eat Plenty of Vegetables”

Popular belief loves reassuring equivalencies. A serving of sweet potato covers needs. A plate of colorful vegetables suffices. Daily carrots protect vision. The problem isn’t that these foods contain nothing. The problem is they contain a metabolic promise, not necessarily a guarantee.

A food can be rich in precursors yet poor in actual effect if your body converts poorly. This is exactly the bioavailability issue. The nutrition label tells you what’s in the food. It doesn’t tell you what your body absorbs, transforms, transports, and uses.

Yet active vitamin A plays fundamental roles: night vision, cellular differentiation, mucous membrane integrity, immunity, reproduction, growth, skin, and intestinal barrier. When status becomes fragile, the body starts cutting back on less urgent functions before a true deficiency manifests.

That’s why deficiency can remain silent for a long time.

Liver: Dense, Powerful, but Not Ordinary

Within a carnivore framework, liver holds a special place. It’s one of the most concentrated sources of retinol. It’s an extremely dense food, not just a “superfood” to consume without thought.

A few dozen grams can provide a significant amount of active vitamin A. This is a strength but also a reason not to use it indiscriminately. Liver should be considered a targeted tool, not a massive daily staple for everyone.

Athletic Carnivore’s approach isn’t to say: “Eat liver every day.” It’s about understanding what the food triggers and what it corrects. For someone coming from a diet low in animal products, with fatigue, dry skin, poor immunity, and signs compatible with fragile status, controlled reintroduction of retinol-rich foods can be very coherent. For someone already consuming many organ meats or supplements, caution is necessary.

Fat, Thyroid, and Conversion

Vitamin A is fat-soluble. It doesn’t circulate in the body like a typical water-soluble molecule. Its absorption depends on the presence of dietary fats, bile, lipid digestion, and hepatic transport. A very low-fat diet can therefore impair vitamin A utilization, even if the plate looks “healthy.”

The thyroid also plays a role. A slowed metabolism or inflammatory terrain can disrupt conversions and micronutrient use. Zinc participates in vitamin A metabolism and transport via RBP, the retinol-binding protein. Vitamin A never acts alone. It functions within a network.

This is exactly where the carnivore approach makes sense: it reunites elements that biologically belong together. Retinol, animal fats, zinc, complete proteins, liver, eggs, fatty fish. It’s not just adding nutrients. It’s a matrix.

The Real Question

The question isn’t whether plants contain beta-carotene. They do. The question is whether your body converts enough of it to meet your actual active vitamin A needs.

Modern nutrition loves to confuse presence with utilization. But the body doesn’t live off what’s written on the label. It lives off what it manages to transform.

And if your diet provides many precursors but few active forms, deficiency can quietly settle in. It doesn’t shout. It simply takes away, function by function, the biological quality you thought you had secured.