Vitamin Atlas

Vitamin A

Vitamin A

Vitamin A is a category containing two groups of related chemicals. The nutrients in one group come from plants like carrots and spinach, while others only come from meat, milk, and eggs. All forms of Vitamin A are fat-soluble, so some digestive disorders and no-fat diets may lead to deficiencies. Your body uses Vitamin A for many purposes, including sight and DNA translation.

What Types of Food Have Vitamin A?

Vitamin A in the World: Polar Peril

Map

Click on the buttons to see how Vitamin A plays a role in your:

  • Nervous System
  • Digestive System
  • General Cellular Function

Nervous System

Vitamin A plays a big role in helping you to see certain types of light. Light travels through the eye’s lens to the retina, located in the back of your eye.

Nervous System

Vitamin A is bound up with a protein in your retina. When light (especially blue-green and low-level light) hits the back of your eye, the Vitamin A changes shape.

Nervous System

Vitamin A’s change in shape sends a signal to your brain, telling it that you are looking at something. This is why people who don’t get enough Vitamin A have trouble seeing at night. Your mom was right — carrots are good for your eyes.

Digestive System

Vitamin A only dissolves in fat. This has a big impact on how your body absorbs it. First, Vitamin A from food or supplements enters the stomach.

Digestive System

Vitamin A then moves from the stomach into the small intestine. Here, a water-soluble vitamin would pass right into your water-filled cells. But Vitamin A doesn’t dissolve in water, so it can’t be absorbed just yet.

Digestive System

Instead, Vitamin A is encased in a bubble of bile before it can pass through the lining of the intestine. The intestinal cells repackage the Vitamin A and send it through the lymphatic system to the rest of the body.

General Cellular Function

DNA is your body’s instruction manual. Every cell has the entire set of DNA, but only needs to read a small part of it to do its job. Vitamin A helps your cells know which parts of the DNA to read. First, Vitamin A enters the nucleus, where DNA is stored.

General Cellular Function

Once inside the nucleus, Vitamin A latches onto certain parts of the DNA, telling the cell which parts of which genes to read (and which to ignore). For example, it tells an embryonic stem cell to take up a career as a red blood cell rather than any other kind.