Vitamin A is a collective term that covers a group of essential, fat-soluble nutrients with a similar structure. The active form of this in our body is called retinol, which can be converted and stored in our liver. Vitamin A is found in both animal and plant foods. The active form, retinol, is found in animal products, while provitamin A carotenoids such as β-carotene are found in plants. There are several forms of vitamin A, including retinol, retinal, and retinoic acid, which are found in animal foods, and various provitamin A carotenoids such as β-carotene, alpha-carotene, and beta-cryptoxanthin, which are found in plant foods. Our body can convert these plant provitamin A into vitamin A and use it. The best known and most important provitamin A is β-carotene. Since the conversion and bioavailability of provitamins A are different, the reference value is also given as retinol equivalent (RE), which mathematically takes into account the differences between vitamin A and provitamins A.
This vitamin is vital for our body because it is necessary for a variety of biological processes such as vision, immune function, cell differentiation and embryonic development.
Vitamin A is an important component of various processes, but the most prominent is the process of vision. Vitamin A is important for maintaining vision in dim light and helps the eye adapt to darkness. Vitamin A is a component of rhodopsin, which enables vision in the retina. Since carrots contain particularly high levels of provitamin A, β-carotene, this is where the saying comes from that carrots are good for the eyes.
Vitamin A is also important for cell differentiation and cell growth. Vitamin A plays an important role in gene expression by binding to receptors in cell nuclei and influencing the transcription of specific genes, which is essential for the normal development and maintenance of cells. It is therefore very important for the development and maintenance of the function of most tissues such as skin and mucous membranes, but also for healthy hair. It can also support wound healing. It is also involved in the development and function of lymphocytes, white blood cells, in blood formation, bone mineralization and in the development of germ cells (egg cells and sperm). Vitamin A also plays an important role in embryonic development, including the maturation of lung tissue. In the immune system, it is needed to regulate certain cells, the lack of which could lead to autoimmune diseases.
In medicine, vitamin A is mainly used in products to combat cancer and to promote healthy skin and skin diseases. Among other things, it is used to combat acne and skin aging caused by sun exposure.
Vitamin A – the most important tasks in brief
The following vitamin A-related health claims have been evaluated and approved by the European Food Safety Authority (EFSA) through scientific studies:
- Vitamin A contributes to normal iron metabolism
- Vitamin A contributes to the maintenance of normal mucous membranes
- Vitamin A contributes to the maintenance of normal skin
- Vitamin A contributes to the maintenance of normal vision
- Vitamin A contributes to the normal function of the immune system
- Vitamin A has a function in cell specialization
Your daily requirement of vitamin A
The German Nutrition Society recommends an intake of 850 µg per day for men and 700 µg per day for women. Pregnant women have an increased need of 800 µg, as do breastfeeding women, for whom 1300 µg is recommended. Nevertheless, pregnant women should avoid regular or excessive consumption of products rich in vitamin A.
Vitamin A is only found in animal foods such as sausages, fish and cheese, especially in the liver.
Provitamin A carotenoids, which our body can convert into vitamin A, are found in plant foods such as peppers, pumpkin, apricots, sweet potatoes, spinach, carrots, egg yolks and green leafy vegetables. Since vitamin A is fat-soluble, when taken from plant sources, a little fat, such as a teaspoon of oil, should be consumed at the same time. The availability of vitamin A in foods can be affected by preparation methods. Long cooking or heating can reduce the vitamin A content. It is recommended to cook foods gently to preserve the nutrients
With a balanced diet, a vitamin A deficiency is unlikely. However, an unbalanced diet, as well as some chronic diseases that affect fat digestion and absorption, such as inflammatory bowel disease, liver disease or pancreatic disorders, can lead to a deficiency. Alcohol abuse, inflammation and kidney disease can also increase the risk. In developing countries, a vitamin A deficiency is the most common cause of blindness and increased mortality in childhood.
An unhealthy maximum amount of vitamin A is set at 3000 µg per day. Health side effects from a high intake of provitamin A from food are not known and there is no maximum limit. Too high an intake of vitamin A from natural foods is unlikely. It is possible if you take too many vitamin A supplements or foods rich in vitamin A. Symptoms of a vitamin A overdose are non-specific and include nausea, vomiting, headaches and blurred vision, as well as muscle pain, dry and red skin, hair loss and brittle fingernails. In pregnant women, it can also lead to embryonic malformations.
How a vitamin A deficiency can manifest itself
A deficiency typically manifests itself in visual disturbances such as night blindness. The blindness caused by long-term vitamin A deficiency can be permanent. This can also lead to drying out of the tear glands and conjunctiva, and even to ulceration of the cornea and blindness.
The immune system is also strongly affected by a deficiency. It is weakened and the susceptibility to infections is higher, especially in the respiratory tract.
Other symptoms include loss of appetite and weight loss, dry, hardened skin and mucous membranes, and general muscle weakness.
In addition to vision problems and a weakened immune system, vitamin A deficiency can lead to growth delays in children, reproductive problems and increased mortality rates
Which AgilNature® products contain vitamin A?
|
product |
Crowd |
NRV* |
|
400 μg RAE per daily ration (1 capsule each) |
50% |
*Nutrient Reference Value = percentage of the reference value according to Annex XIII of the Food Information Regulation (EC) No 1169/2011.
Literature:
- Vitamin A. DGE. https://www.dge.de/wissenschaft/referenzwerte/vitamin-a/ (accessed on January 21, 2024)
- Regulation (EC) No. 1924/2006 (Health Claims)
- Blaner WS, Li Y, Brun PJ, Yuen JJ, Lee SA, Clugston RD. Vitamin A Absorption, Storage and Mobilization. Subcell Biochem. 2016;81:95-125.
- Carazo A, Macáková K, Matoušová K, Krčmová LK, Protti M, Mladěnka P. Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity. Nutrients. 2021 May 18;13(5):1703.
- Zinder R, Cooley R, Vlad LG, Molnar JA. Vitamin A and Wound Healing. Nutr Clinic Pract. 2019 Dec;34(6):839-849.
- VanBuren CA, Everts HB. Vitamin A in Skin and Hair: An Update. Nutrients. 2022 Jul 19;14(14):2952. doi: 10.3390/nu14142952.
