Medically the review by Natalie Olsen, R.D., L.D., ACSM EP-C — composed by Jenna Fletcher on January 17, 2020

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You are watching: By definition, a vitamin is all of the following except:

Fat-soluble vitamins room vitamins A, D, E, and also K. They are existing in foods containing fats. The body absorbs this vitamins as it does diet fats. They perform not dissolve in water.

Vitamins help the body duty effectively. There are two types: water-soluble and also fat-soluble vitamins. The water-soluble vitamins are vitamins B and also C.

Most vitamins come indigenous food, but sunshine contributes come vitamin D. Some human being need or select to take it supplements that carry out extra vitamins.

The body absorbs fat-soluble vitamins ideal when a human being eats them with higher-fat foods.

This write-up looks at the types, functions, and sources the fat-soluble vitamins, and also what can take place if a person has actually too lot or also little.

Vitamin A

Share top top PinterestCarrots space a dietary resource of vitamin A.
Vitamin A helps maintain healthy and balanced vision. Without vitamin A, a person can experience vision problems and also possibly vision loss.


Vitamin A is not a solitary vitamin yet a arsenal of compounds known as retinoids. Retinoids occur naturally in the human body, and also they are existing in part dietary sources.

Some foods provide retinols, i m sorry the body deserve to use straight as vitamin A. Others administer provitamin A, compounds the the human body converts into vitamin A.


Vitamin A support several attributes throughout the body, including:

visionthe immune system

Learn more here around why we require vitamin A.

Dietary sources

People can obtain vitamin A v dietary sources.

Animal sources provide preformed vitamin A, or retinols. This form is ready for the human body to use.

Plant sources provide carotenoids, such together beta-carotene, which is a powerful antioxidant. The human body can convert these into vitamin A.

For this reason, lists of ingredients often show vitamin A content as “vitamin A RAE.” RAE method “retinol task equivalents.”

Animal resources of vitamin A include:

fish liver oilbeef livercheese, milk, and other dairy product productsSources the beta carotene include:sweet potatocarrotscantaloupeblack-eyed peasfortified breakfast cereals

Find out more here about dietary sources of vitamin A.

Recommended intake

Nutritionists measure some vitamins in two ways:

micrograms (mcg) RAEinternational devices (IU)

Food packages usually show the quantities in IU. A diet that has 900 mcg RAE the vitamin A, i beg your pardon is the encourage intake because that males end 14 years of age, would carry out around 3,000–36,000 IU that vitamin A, follow to the Office of diet Supplements (ODS).

Anyone who has concerns about their vitamin A intake must seek advice indigenous a wellness professional, that will assist them know these measures.

The encourage intake of vitamin A different by age and sex.

The 2015–2020 dietary Guidelines for Americans recommend consuming the following quantities each day. Amounts are in mcg RAE.

Age (years)1–34–89–1314 and over


Vitamin A deficiency is rarely in the joined States, yet it can impact a person who:

follows a plant-based diet

A permanent deficiency deserve to lead to a ns of night vision and possibly a full loss that vision.


Too lot vitamin A can be toxic.

It have the right to affect:

people who take vitamin A supplementsthose with a high input of fish liver oil

During pregnancy, high levels of vitamin A can injury a growing fetus.

Symptoms of one overdose include:


In major cases, coma and also death have the right to result.

Vitamin A additionally are available for purchase online. However, civilization should speak to a doctor prior to taking this or other supplements.

The time a person takes a vitamin can influence its impact. Discover out an ext here about when come take different vitamins.

People achieve vitamin D:

naturally v exposure to sunlight or in the dietthrough fortified foodsas supplements

The human body obtains the compound it demands to do vitamin D indigenous food. It likewise produces vitamin D when ultraviolet (UV) light meets the skin.


Vitamin D is not a solitary substance yet a group of compounds collectively known together calciferol.

The human body absorbs calciferol into the bloodstream and then converts it to calcitriol.

Two varieties occur naturally:

vitamin D-3, uncovered in pet fatsvitamin D-2, discovered in plants, such together mushrooms


Vitamin D has actually two key roles in the body:

It maintains bone health.It support the immune system.

Find out an ext about the health and wellness benefits of vitamin D.

Dietary sources

A human being can obtain some vitamin D indigenous the sun, yet most civilization will additionally need to use various other sources, too. The main alternate is food.

Dietary sources include:

fortified dairy products, plant-based milks, and cerealsbeef livereggs

How can you get more vitamin D from the sun? Click right here to discover out.

Recommended intake

Experts measure up vitamin D in worldwide units (IU).

Current guidelines recommend that civilization of all ages intake of 600 IU that vitamin D daily. This is hard to measure, however, together it is not easy for a human to know how much vitamin D they acquire from sunlight.


A vitamin D deficiency deserve to affect:

older adults and children who perform not spend much time the end of doorspeople through darker skinsome world with chronic health conditionsthose who live far from the Equator, whereby winter days space short

The main impacts of vitamin D deficiency include:

osteomalacia, as soon as bones become softincreased hazard of infection and autoimmunity

Learn an ext about vitamin D deficiency.


It is rarely for a human being to have too lot vitamin D, but using supplements could trigger this.

Having too much vitamin D might lead to high level of calcium in the blood.

This deserve to lead to:

nauseaheadacheslow appetite and weight lossa buildup that calcium in tissues and also blood vesselsheart or kidney damage

Vitamin D additional are obtainable for purchase in pharmacies and also online. A human should speak to your doctor before using these supplements, however.

Vitamin E is one antioxidant that can assist the body destroy totally free radicals. Totally free radicals space unstable atoms that can reason oxidative stress. Oxidative stress have the right to lead to cabinet damage, and this can an outcome in cancer and also other diseases. Vitamin E may assist protect the body from a variety of health and wellness issues.


There are eight creates of vitamin E, yet only alpha-tocopherol meets humans’ needs, according to the ODS.


Some factors why the body demands vitamin E are:

as an antioxidantto an increase the immune systemto dilate blood vessels and aid prevent clotting

Dietary sources

Good sources of vitamin E include:

wheat germ oilsunflower seeds and also oilalmonds, hazelnuts, and peanutsspinach and also broccoli

Which foods items are good sources of vitamin E? uncover out here.

Recommended intake

Current guidelines recommend human being consume the following amounts of vitamin E. Professionals measure vitamin E intake in milligrams (mg) AT, however packaging currently uses worldwide units (IU).

Age (years)1–34–89–1314 and over
Female6 mg (9IU)7 mg (10.4 IU)11 mg (16.4 IU)15 mg (22.4 IU)
Male6 mg (9IU)7 mg (10.4 IU)11 mg (16.4 IU)15 mg (22.4 IU)

The ODS keep in mind that, during breastfeeding, a female have to consume 19 mg (28.4 IU) every day.


Vitamin E deficiency is rare, however it can affect people through Crohn’s disease or cystic fibrosis. These conditions affect the liver’s capability to absorb vitamin E.

A deficiency can an outcome in:

nerve and also muscle damage that influence movement and also coordinationvision problemsa weakened immune system

As vitamin E is one antioxidant, a permanent deficiency can increase the all at once risk of assorted diseases.

Click right here to uncover out exactly how to identify a vitamin E deficiency.


Obtaining vitamin E through organic sources is i can not qualify to lead to an overdose, although supplement use have the right to increase this risk.

People who use blood-thinning medication, such as warfarin (Coumadin) must ask your doctor prior to taking vitamin E supplements, together these may interfere v blood clotting.

Vitamin E additional are easily accessible for purchase in pharmacies and online.

Vitamin K help the body type blood clots. Blood coagulation is necessary to prevent extreme bleeding.


There room several types of vitamin K.

The two most common groups are:

Vitamin K-1 (phylloquinone), current in green, irpari vegetables and some other plant sources

There are additionally synthetic forms and other creates that the human body makes.


Apart indigenous blood clotting, vitamin K may also:

enhance bone healthreduce the buildup the calcium in the blood

Learn an ext here about why we require vitamin K and where to get it.

Dietary sources

Food resources of vitamin K-1 and K-2 include:

kaleliverspinachparsleybutteregg yolks

Learn about 40 foods items that administer vitamin K.

Recommended intake

Experts execute not have sufficient evidence to introduce a details intake that vitamin K perfect to accomplish the requirements of 97-98% of healthy and balanced individuals.

Instead, they introduce an adequate intake (AI), an lot assumed to administer nutritional adequacy, together follows:

Age (years)1–34–89–1314–1819 and over


The body is no able to keep as much vitamin K together it walk vitamin A or D. This way a human being needs a consistent intake the vitamin K, and there is a greater chance that a deficiency.

A vitamin K deficiency may result in:

excess bleedinglower bone density, in the long term

Learn more about a vitamin K deficiency here.


Taking high amounts of vitamin K does not appear to bring about adverse effects. However, it deserve to interfere through the usage of blood-thinning medications, such together warfarin (Coumadin).

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Vitamin K supplements are available for purchase in pharmacies and online. However, world should speak to a doctor before using them, specifically if they usage blood thinners or have a condition that influence blood clotting.