What to Know About Vitamins A, D, E, and K

April 2024

There are six main vitamins — A, B, C, D, E, and K. Not all vitamins are alike though. Some are water soluble, meaning that they dissolve in water, while others — A, D, E, and K — are fat-soluble. This means that they dissolve in fat, not in water.

How the body absorbs and stores a vitamin depends, in large part, on whether it is soluble in fat or water. Fat-soluble vitamins need to be eaten with fat for the best absorption. For veggies that are high in one or more of these vitamins, you can add olive oil or butter directly to them — or simply consume them as part of a meal that contains some fat.

Unlike water-soluble vitamins, your body doesn’t easily excrete excess amounts of fat-soluble vitamins. This means it’s easier for you to take too much of them (if you’re taking supplements).

Fat-soluble vitamins are less likely to be absorbed well by people with medical conditions that don’t allow them to absorb fat properly — for example, celiac disease or Crohn’s disease.

Here’s what you need to know about each of the fat-soluble vitamins.

Vitamin A

Vitamin A is necessary for normal vision function, reproduction, immune system, and general growth and development. Your organs also need vitamin A in order to work properly.

Many animal products are rich in vitamin A. This includes eggs, fish, dairy products, and organ meat. Many fruits and vegetables contain carotenoids, which the body then converts into vitamin A. Vegetables that are high in carotenoids include:

  • Green leafy vegetables, like spinach and kale.
  • Other green vegetables, like broccoli.
  • Orange and yellow vegetables, like carrots, sweet potatoes, and yellow peppers.
  • Orange and yellow fruits, like cantaloupe, apricots, peaches, and mangos.

According to the National Institute of Health (NIH), vitamin A deficiency is rare in the U.S.

Vitamin D

Vitamin D is a critical vitamin for building strong bones. That’s because vitamin D helps your body absorb calcium. Vitamin D is also necessary to strengthen your immune system to fight off viruses and bacteria.

Your body makes vitamin D when your skin is exposed to sunlight. Not very many foods naturally contain Vitamin D. The few that do are fatty fish. Fish liver oils are also a good source. Most dietary sources of vitamin D in the U.S. come from fortified milk. Breakfast cereals, orange juice, and yogurt may also be fortified.

The NIH estimates that roughly one out of every four Americans has vitamin D levels that are too low for good bone health.

Vitamin E

Vitamin E is one of the key antioxidants. It helps protect your body from “free radicals,” which are compounds people are exposed to from things like pollution, UV light, cigarette smoke, and even the byproducts of your body converting food to energy. Vitamin E also helps boost your immune system and helps keep your blood vessels open and free of blood clots.

Fortunately, vitamin E is found naturally in many foods. Nuts are especially good sources of vitamin E. Green vegetables (like broccoli and spinach) are also good sources. Some juices, margarines, and breakfast cereals may also be fortified with vitamin E.

The NIH reports that vitamin E deficiency in the U.S. is very rare.

Vitamin K

Vitamin K is a vitamin that’s needed (along with vitamin D and calcium) for building healthy bones. It’s also necessary for your body to form blood clots.

Vitamin K is found naturally in many foods, including:

  • Green leafy vegetables, like kale, collards, spinach, and dark lettuce.
  • Broccoli.
  • Certain fruits, like figs and blueberries.
    Protein sources like eggs, meat, cheese, and soybeans.

According to the NIH, it’s rare for Americans to be deficient in vitamin K. If you’re taking a blood thinner, it’s critical that you get roughly the same amount of vitamin K from your diet every day.

If you have questions about any of these vitamins, your local pharmacist can help.

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