Are You a Beta Carotene to Vitamin A Low Converter?

Vitamin A: Why Plant Sources Aren’t the Same as Animal Sources

When you think of getting enough vitamin A, what’s the first food that pops into your mind? Carrots? Sweet potatoes?

You might be surprised to learn that neither of these contain actual vitamin A — and in fact, no plant foods do.

Beta Carotene vs. Vitamin A

Bright orange foods contain beta carotene, a type of carotenoid.

Carotenoids aren’t vitamin A. They’re provitamin A, meaning the body must convert them into vitamin A. An intestinal enzyme breaks down these carotenoids so they can be turned into their active form.

Actual vitamin A — also known as preformed vitamin A — is found only in animal foods. This includes retinol and retinyl esters. Retinol isn’t usually present in foods; retinyl esters (like retinyl palmitate) are what you find in animal sources.

Plant foods contain hundreds of carotenoids, but only about 10% can be converted into retinol — and even those vary significantly in how well they convert. (1)

Can Beta Carotene Be Absorbed Efficiently?

On nutrition labels you’ll see vitamin A listed in micrograms (mcg) or international units (IU), but these numbers don’t automatically reflect how absorbable the source is.

Plant forms like beta carotene convert to vitamin A at an estimated 3.6–28:1 ratio by weight. In some cases, only a small percentage becomes usable retinol. For example, one study found that only about 2% of the beta carotene in raw carrots was converted. (2)

If you’re curious about the Retinol Activity Equivalent (RAE) values for specific plant foods, you can look them up in the USDA’s FoodData Central. (3)

Why Conversion Varies From Person to Person

Conversion isn’t the same for everyone. It may be influenced by factors such as:

• general health

• digestive function

• alcohol intake

• genetics

Carotenoids are converted by an enzyme called β-carotene 15,15′-monooxygenase (BCMO1). This enzyme turns carotenoids into retinal, which is then made into retinol. (4)

Around 45% of people have a common genetic variation that reduces BCMO1 activity — meaning their bodies don’t convert carotenoids efficiently. Some studies suggest this reduction can be as high as 70%. (5)

How to Check Whether You’re a “Low Converter”

If you have 23andMe, you can look up certain markers related to BCMO1.

In the chart below (from the original content), type the SNP into the search bar → press Enter → click “marker” → and look for the genotype listed under “Your Genotype.”