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Vitamin A

I. Introduction

Health is one of the most important issues for every human being . Therefore, it is also important to know which nutrients we should supply our body with in order to stay healthy and fit. In this article we will deal with one of the most important nutrients for our health: Vitamin A. We will explain what vitamin A is, how it works in the body, where it comes from and what the consequences of a deficiency or overdose can be. At the end we will provide recommendations on how to maintain healthy levels of vitamin A in the body.

Definition of vitamin A

Vitamin A, also known as retinol, is a fat-soluble vitamin that helps the body regulate a variety of functions. It is involved in almost all physiological processes, including immune system function, vision, growth and development of body cells, and reproduction. Vitamin A is a fat-soluble vitamin, which is why it can be stored in fat solutions in our body. We can absorb the vitamin both in its active form as retinol or in its precursor form as carotenoids. These precursors of vitamin A (also called provitamins) are only converted into active vitamin A in our body after it has been absorbed. In fact, we can also synthesize vitamin A ourselves through UV radiation. However, the amount that can be synthesized is far from sufficient to cover our daily needs.

II. Function of vitamin A

Vitamin A is an essential nutrient involved in many biological processes. It supports the immune system , maintains vision, promotes cell division and stimulates cell growth.

How vitamin A works in the body

Vitamin A is absorbed through the small intestine, from where it is transported to the liver for storage. It is stored in the liver in the form of retinyl esters. Retinol serves as a precursor molecule for other forms of vitamin A. Retinaldehyde, retinoic acid and retinoic acid ester can be formed from retinol. For example, retinaldehyde plays an important role in regulating vision, while retinoic acid is involved in cell division and regeneration, and retinoic acid esters are involved in pigment formation and supporting immune function.

The importance of vitamin A for the immune system

Vitamin A contributes to a well-functioning immune system. It supports the growth and differentiation of immune cells, promotes the formation of antibodies and supports the functional activity of immune cells.

In addition to these direct effects, vitamin A also has a positive impact on other body systems that affect the immune system. It can inhibit the body's inflammatory response and help make us less susceptible to infection. It can also help improve gut health and strengthen the gut barrier, which allows the immune system to develop and function better. In addition, it is involved in the protection of the skin and mucous membranes.

The role of vitamin A in supporting vision

Vitamin A is an essential nutrient that supports vision. It is an important part of the visual process and is needed in the retina to enable visual perception. The nutrient is also involved in several biochemical circuits in the body that affect our vision.

Vitamin A is also necessary to produce a healthy dose of pigment in our eyes. This pigment absorbs light in order to be able to perceive different colors and levels of brightness. It also forms a protective layer on the cornea of ​​our eyes.

Adequate intake of vitamin A in the diet can help maintain healthy vision. It can prevent deposits on the retina that can lead to vision problems.

The importance of vitamin A for cell growth

Vitamin A is important for regulating cell growth and cell differentiation. It is involved in a number of processes that contribute to healthy cell function.

The direct influence of vitamin A on cell growth and differentiation stems from its role in the synthesis, regulation, and activation of various cellular proteins . These proteins are necessary for various functions in cells and tissues, including cell growth and cell differentiation. An example is retinoic acid, an isomer of vitamin A that is produced in the body and is involved in regulating the expression of numerous genes. It can be assumed that a lack of vitamin A impairs cell growth and cell differentiation.

Another important factor influencing vitamin A on cell growth is its ability to promote cell division. It allows cells to divide faster and produce more substance, which is necessary for rapid growth and differentiation. Vitamin A also improves cell structure and function by strengthening cell membranes and regulating the activity of certain enzymes. It can also increase the rate of cell division.

III. Sources of vitamin A

Vitamin A comes in two different forms: retinol and carotenoids. Retinol is found exclusively in animal foods, while carotenoid is mainly found in plant products. Both forms are absorbed by the body and can be used equally.

Natural sources of vitamin A

Natural sources of carotenoids are vegetables such as carrots, spinach, broccoli, cauliflower, sweet potatoes, squash, and tomatoes. Many types of fruit such as apricots, peaches, berries and melons, as well as nuts and seeds such as peanuts, walnuts and sesame are good sources of the vitamin.

Retinol is only found in animal foods. It can be made from different types of fish such. As salmon, tuna, mackerel and sardines or from eggs, milk or milk products.

Dietary supplements and fortified foods

An additional supply of vitamin A can be useful if the vitamin A level is already low or if you are following a diet that does not contain enough vitamin A. Dietary supplements are usually available over the counter as tablets in pharmacies and health food stores. Another way to increase vitamin A levels is to use vitamin A-fortified products. Examples can be dairy products, ready meals, juices and bread.

Daily requirement of vitamin A

The daily optimal amount of vitamin A depends on various factors such as age and gender. The German Society for Nutrition (DGE) recommends the following daily doses depending on age and gender:

Old retinol
in micrograms/day
m w
0 to under 4 months 500
4 to under 12 months 400
children and young people
1 to under 4 years 300
4 to under 7 years 350
7 to under 10 years 450
10 to under 13 years 600
13 to under 15 years 800 700
15 to under 19 years 950 800
19 to under 25 years 850 700
25 to under 51 years 850 700
51 to under 65 years 850 700
65 years and older 800 700
pregnant women 800
breastfeeding 1300

IV. Possible effects of vitamin A deficiency

A lack of vitamin A can have serious health consequences. If one of the symptoms listed below occurs, a doctor should always be consulted in order to uncover the cause of the symptom and, if necessary, to avoid long-term negative effects of insufficient vitamin A supply.

Symptoms of vitamin A deficiency

A vitamin A deficiency can have serious consequences if it is not recognized and treated in time. The following symptoms and consequences can be caused by a deficiency:

  • Vision changes including visual disturbances, night blindness, photophobia and reduced visual acuity
  • impairment of immune function
  • muscle weakness
  • dry skin
  • skin rashes
  • inflammation
  • thinner and rougher cornea of ​​the eyes
  • Miscarriage, premature birth or low birth weight of children

Who is most commonly affected by vitamin A deficiency?

A lack of vitamin A is common worldwide and mainly affects people in developing countries. According to a 2017 study, more than 250 million people suffer from a lack of vitamin A supply.

Children are particularly at risk due to their immature immune system in connection with an increased need. They make up around 70 percent of those affected. Other risk groups are pregnant women, the chronically ill and malnourished people.

V. Possible consequences of an overdose of vitamin A

Too high a dose of vitamin A can also cause undesirable side effects. If typical symptoms occur, a doctor should always be consulted in order to avoid further health complications. Since some symptoms can also indicate other deficiency symptoms or diseases, the cause of the symptoms should also be clarified.

Symptoms and consequences of vitamin A overdose

  • yellowing of the skin
  • tiredness or poor sleep
  • dry skin and mucous membranes e.g. B. in the mouth
  • Decreased eyesight
  • Decreased concentration
  • mood swings
  • vomiting or diarrhea
  • Headache
  • dizziness
  • memory loss
  • renal dysfunction
  • muscle weakness
  • joint pain

A high dose of vitamin A can also lead to more severe symptoms such as jaundice, flushing, fever, bleeding and even liver failure in some cases. To avoid this, the intake of supplements or fortified foods should always be clarified with a doctor.

Who is most likely to suffer from a vitamin A overdose?

Children and adolescents are particularly susceptible to vitamin A poisoning. Your body is still growing and you are more likely to be consuming more foods containing vitamin A than you need. Another reason children and teenagers are more susceptible is that their organs and systems are not yet mature and they have a hard time removing excess vitamins from the body.

People who already have hepatitis B are also at increased risk of vitamin A poisoning. This is because by infecting the liver cells with the virus, the vitamin is lost in the body.

Pregnant women must be particularly careful, as incorrect dosing during pregnancy can lead to serious complications for both mother and child.

VI. Conclusion

Vitamin A is an important nutrient for the body and an essential part of a healthy diet. It contributes to overall health by supporting cell growth, wound healing and immune system function. It also has a number of specific functions that make it essential for different parts of the body, such as our skin and mucous membranes, eyes or our nervous system.

Vitamin A comes in two forms: retinol and its precursor, the carotenoid (provitamin A). Retinol is found in many animal products while carotenoid is found in plant foods. The latter are only converted into vitamin A in our body.

A lack of vitamin A can have serious consequences, including reduced immune function, night blindness and an increased risk of various diseases. People who are not consuming enough vitamin A should consider supplementing with vitamin A or making dietary changes to meet their daily needs.

The daily dose of vitamin A depends on age and gender and should always be individually adjusted to prevent the undesirable consequences of incorrect dosing.

Vitamin A is one of the fat-soluble vitamins and can therefore be easily stored in the body. For this reason, it is important not to consume too much of it to avoid side effects.

Recommendations for maintaining healthy levels of vitamin A in the body

It is important to get enough vitamin A through a balanced diet. To maintain healthy vitamin A levels, the following recommendations can be followed:

  1. Consume foods that contain retinol: Good sources include liver, but also fish, eggs, and dairy products.
  2. Make sure you're getting enough natural carotenoids: These are found in certain vegetables, especially dark green, red, and orange vegetables.
  3. Vitamin A intake through supplements: In the case of an existing deficiency or insufficient intake through the diet, vitamin A dietary supplements or fortified foods can help to cover the daily requirement.

frequently asked Questions

What is the difference between vitamin A and beta carotene?

Vitamin A and beta-carotene (also β-carotene) are carotenoids that can be converted to vitamin A in the body (pro-vitamin A). Also known as retinol, vitamin A is found in animal foods like liver, eggs, and dairy products, while beta-carotene is found in vegetables like carrots, kale, and sweet potatoes. The main difference between the two is that vitamin A is directly absorbed by the body, while beta-carotene must first be converted into vitamin A before it can be used by the body.

Which foods contain vitamin A?

Vitamin A is found in many animal foods such as liver, eggs, dairy products and fish oil. It's also found in vegetables like carrots, spinach, broccoli, and sweet potatoes.

How much vitamin A does the body need per day?

The DGE recommends a daily intake of 800-850 micrograms for adult men and 700 micrograms for adult women per day to meet vitamin A requirements. Due to special circumstances such as B. a pregnancy, the need may be increased. In this phase, women need about 1.3 mg of vitamin A per day.

Can an overdose of vitamin A be dangerous?

Yes, too high a dosage can cause serious health problems, especially if taken for a long period of time. Too much vitamin A can cause nausea, vomiting, headaches, fatigue and even liver damage.

How is vitamin A deficiency diagnosed and treated?

A vitamin A deficiency can be diagnosed by a blood test. The deficiency can be corrected with a balanced diet with sufficient amounts of vitamin A. In severe cases, supplementation may be necessary.

Can Vitamin A Improve Vision?

Yes, vitamin A is good for the eyes. It plays an important role in eye health and can improve vision. It is important for the retina and helps maintain eye moisture.

Can Vitamin A Help With Skin Problems?

Yes, vitamin A can help treat skin problems like acne, psoriasis, and wrinkles. It promotes skin cell growth and repair and helps regulate sebum production.

Is Vitamin A Safe for Pregnant and Nursing Moms?

In moderation, vitamin A is safe for pregnant women and nursing mothers. However, intake above 1,300 micrograms per day should be avoided to prevent fetal malformations and birth complications. Pregnant women and nursing mothers should always consult their doctor before taking any dietary supplement.

Can Vitamin A Help With Cancer Prevention?

There are some studies that suggest that getting enough vitamin A can reduce the risk of cancer. In particular, a link has been found between higher consumption of foods rich in vitamin A and lower risk of certain types of cancer, such as lung cancer and prostate cancer. However, more studies are needed to confirm this association and to determine whether vitamin A may actually play a role in cancer prevention.

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