What Is Vitamin A In International Units?

freeze-dried parsley on a plate
Vitamin A is found in freeze-dried parsley

Vitamin A is the name of a group of fat-soluble retinoids. Two forms of vitamin A are available in the human diet: preformed vitamin A and provitamin A carotenoids.

IU is a unit of measurement for fat-soluble vitamins, like vitamin A.

Vitamin A is found naturally in many foods. It can also be added to fortified foods.

Getting too much-preformed vitamin A, the form found in supplements, over a prolonged period, can lead to toxicity. Supplementation should only be used periodically.

Toxicity from food sources is rare.

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Vitamin A Is An Essential

Vitamin A is not just one vitamin. It is the name of a group of fat-soluble retinoids, like retinol, retinal, and retinyl esters. (source )

Vitamin A is an essential nutrient that cannot be synthesized in the body. Therefore, it must be obtained through diet. (source )

It plays an important role in growth, reproduction, immune function, vision, and tissue maintenance.

What is IU?

IU stands for International Units. It’s a unit of measurement for vitamins and other specific substances. It is commonly used to measure fat-soluble vitamins, like Vitamins A, D, and E.

Vitamins are measured in milligrams, micrograms, or international units. Milligrams and micrograms show the amount of mass in a sample. But international units show the level of biological activity of the substance. (source )

For unit conversion, the formula is:

To convert Vitamin A as retinol:

From IU to mcg: IU * 0.3 = mcg

Example: 5000 IU * 0.3 = 1500 mcg

(source )

Why Measure Vitamin A In IU?

International Units (IU) are a measure based on the biological activity of a substance in the body.

An IU is the amount of a substance that has a certain biological effect.

This means how much of that vitamin is going to make a difference in your body. IU measures how specific forms of vitamins are going to react in your body differently.

Foods You Can Find Vitamin A Measured In IU, In

You find vitamin A measured in IU mostly in fats and oils, american indian and alaska native food, beef, and vegetable products.

Examples of food sources include

Foods in our nutrition tool

You can find regularly updated, top ranked lists of foods for over 200+ nutrients in our nutrition tool.

If you are interested in what foods contain the most vitamin A measured in IU, we recommend you visit our tool.

Here's our top ranked list of foods that contain Vitamin A, IU.

Sara Niemelä

co-founder Care Omnia, Head Content Creator

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Nutrition is my passion. I've spent thousands upon thousands of hours reading, analyzing, categorizing and comparing research studies.

I’m a wife and a mother of three. I enjoy the outdoors, cooking, and spending time with my family.