Definitive Guide To Fat-Soluble Vitamins

Good nutrition is essential to have a healthy lifestyle. Also, within the nutrients we can get different types; However, one of the most important and essential for the body are vitamins.

Most vitamins are soluble in water, that is, they can be dissolved in water. However, there are other fat-soluble vitamins, such as vitamins A, D, E and K.

Each of the fat-soluble vitamins have a particularity, and, of course, a different use.

Guide to fat-soluble vitamins

1.Vitamin A

As you have ever heard, vitamin A plays a key role in eye health.

1.1 Types of vitamin A

First of all, you should know that vitamin A is a set of fat-soluble compounds known as retinoids. Under this scheme, the most common way to find vitamin A is retinol since; other forms such as retinal acid or retinoic acid are rarely found in food.

1.2 Function of vitamin A

Although vitamin A is known for its benefits in eye health, it actually contributes to several functions of the body such as the following:

  • Improves immune function: consuming vitamin A helps strengthen the immune system.
  • Body growth: Deficiency of this vitamin can delay growth, especially in children.
  • Hair growth: the deficiency of this vitamin is related to alopecia or hair loss.
  • Reproductive function: vitamin A is essential for fertility and vital for the development of the fetus.

1.3 Dietary sources of vitamin A

Vitamin A is found in foods of animal origin, especially in the liver, fish liver oil and butter . However, it can also be found in certain carotenoid antioxidants found in plants.

The most efficient of these is beta-carotene, which is abundant in carrots, kale and spinach.

1.4 Recommended intake of vitamin A

For adult men, the recommended daily dose is 3,000 IU, while in women it is 2,333 IU. In the case of children, the recommended dose ranges from 1,000 IU to 2,000 IU.

1.5 Negative effects of vitamin A deficiency

Although vitamin A deficiency is rare, there are risks of deficiency in developing countries or in people who adopt a vegan diet .

Among some symptoms and consequences of vitamin A deficiency are the following:

  • Dry eyes.
  • Blindness
  • Hair loss.
  • Problems in the skin
  • Deficiency in the immune system.

2.Vitamin D

Did you know that vitamin D is produced in the skin when it is exposed to sunlight? Therefore it is known as the sun’s vitamin. In turn, this vitamin is known for its beneficial effects on bone health, since most of the fractures are related to the deficiency of this vitamin.

2.1 Types of vitamin D

Vitamin D has two main forms:

  • Vitamin D2 ( ergocalciferol ): found in fungi and some plants.
  • Vitamin D3 ( cholecalciferol ): found in foods of animal origin, such as eggs and fish. It also occurs on the skin when exposed to sunlight.

2.2 Function of vitamin D

Although vitamin D has many positive health effects, only a few are sufficiently researched. Among them, the two main functions of vitamin D are:

  • Maintenance of calcium in the body: vitamin D regulates the levels of calcium and phosphorus, minerals essential for bone growth and its maintenance. In addition, it promotes the absorption of these minerals in the diet.
  • Regulation of the immune system: regulates and strengthens the function of the immune system.

2.3 Dietary sources of vitamin D

The body can produce enough vitamin D that is needed as long as there is constant exposure of the skin to the sun. However, perhaps some people do not constantly expose their skin to the sun, and if they do, it is with enough clothes on, so that the production of vitamin D in its natural form decreases noticeably. For this reason, it is common to obtain vitamin D through supplements or foods.

Among the foods that contain more vitamin D are the following:

  • Fish or fish oil
  • Mushrooms exposed to ultraviolet light.
  • Dairy and margarine
  • Eggs

2.4 Recommended intake of vitamin D

For children and adults, the recommended daily intake of vitamin D is 600 IU (15 mcg). However, in elderly adults the dose can be increased to 800 IU (20 mcg).

In any case, the ideal is to consult your trusted doctor for a recommended dose according to your needs.

2.5 Negative effects of vitamin D deficiency

Extreme vitamin D deficiency is rare. However, when this happens, the most common negative effects and symptoms are:

  • Soft bones and weak muscles.
  • Weak immune system (higher risk of diseases).
  • Fatigue
  • Depression .
  • Hair loss.
  • Slow healing of wounds.

3.Vitamin E

Vitamin E is known mainly for its antioxidant functions, since it combats premature aging and free radicals.

3.1 Types of vitamin E

Vitamin E is composed of eight structurally similar antioxidants that are divided into two groups:

Tocopherols : alpha-tocopherol, beta-tocopherol, gamma-tocopherol and delta-tocopherol.

Tocotrienols : alpha-toctrienol, beta-toctrienol, gamma-tocopherol and delta-tocotrienol.

The most common form of vitamin E is alpha-tocopherol, constituting 90% of vitamin E found in the blood.

3.2 Function of vitamin E

As you have seen, the main function of vitamin E is to serve as an antioxidant in the body, preventing oxidative stress and the protection of fatty acids in the cell membranes of free radicals. However, when combined with other nutrients such as vitamin C, its properties can be reinforced.

3.3 Dietary sources of vitamin E

The best sources of vitamin E are the following:

  • Vegetable oils.
  • Nuts
  • Fresh fish.
  • Fish liver oil

3.4 Recommended intake of vitamin E

In adults, the recommended daily dose is 23 IU (15 mg) while, for children and adolescents, the recommended daily dose ranges from 9 IU (6 mg) to 23 IU (15 mg).

3.5 Negative effects of vitamin E deficiency

In general, vitamin E deficiency is rarely diagnosed, much less in people with stable health.

However, some of the main symptoms of vitamin E deficiency are:

  • Muscular weakness.
  • Dificulty to walk.
  • Tremors
  • Vision problems.
  • Entumption

Cases of excessive deficiency can cause diseases such as anemia, heart disease, severe immunological problems, blindness, dementia, decreased reflexes, and even inability to completely control the movements of the body.

Consequences of having a Vitamin E deficiency

4.Vitamin K

In the case of vitamin K, it plays a key role in the coagulation of blood, since without it would run a serious risk of death by bleeding before any wound.

4.1 Types of vitamin K

Vitamin K is a group of several fat-soluble compounds divided into two main groups:

  • Vitamin K1 ( phylloquinone ): found in plant-type foods.
  • Vitamin K2 ( menaquinone ): in this case it is mainly found in foods of animal origin and fermented soy products.

In addition, there are also three synthetic forms of vitamin K:

  • Vitamin K3 ( menadione ).
  • Vitamin K4 ( menadiol diacetate ).
  • Vitamin K5

4.2 Function of vitamin K

In addition to being an essential part of the blood coagulation process, vitamin K can have other functions such as contributing to better bone health and helping to prevent the calcification of blood vessels, reducing the risk of heart disease.

4.3 Sources of vitamin K

The best sources of vitamin K1 are green leafy vegetables, while vitamin K2 is found mainly in foods of plant origin and fermented soy products.

Vitamin K can also be found in foods such as liver, egg yolks and butter.

4.4 Recommended intake of vitamin K

The recommended daily intake of vitamin K is 90 mcg for men and 120 mcg for women. In the case of children and adolescents, the adequate intake ranges between 30-75 mcg depending on the age group.

4.5 Negative effects of vitamin K deficiency

Unlike other vitamins, vitamin K is not stored in large quantities in the body, so it is more likely to be deficient in the case of not eating a proper diet and healthy.

Among the main negative effects of vitamin K deficiency are the difficulty to heal wounds and the risk of excessive bleeding. Therefore, the consumption of vitamin K is essential for all people.


Fat-soluble vitamins are essential for the proper functioning of the body. Most of these can be easily obtained through healthy foods such as seeds, nuts, fish and eggs. However, if you do not have a healthy diet or for some medical reason it is difficult for you to absorb vitamins, it is best that you choose to include vitamin supplements in your diet, which you can buy through Amazon Spain .

Finally, always keep in mind that a medical opinion is important to know how your body is, to know if you have any deficiency of these vitamins and what would be the recommended dose according to your specific case.

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