Calciferols (Vitamin D)

Calciferole (Vitamin D)


Vitamin D is used as a generic term for a group of fat-soluble vitamins. These include vitamin D3, cholecalciferol, and vitamin D2, ergocalciferol. Vitamin D precursors are present in our body from which vitamin D can be formed under sunlight, more specifically under UV-B radiation. In contrast to other vitamins, the main source is not food, but rather the body's own production.  


The main function of vitamin D is to participate in calcium and phosphate metabolism. By promoting the absorption of calcium and phosphates from the intestine and increasing calcium levels in the plasma, vitamin D ensures bone mineralization. It is primarily important for bone hardening, but the vitamin is also involved in numerous other metabolic pathways and gene regulations. It is involved in the immune system and also influences muscle strength.  



Vitamin D – the most important tasks in brief  

The following vitamin D-related health claims have been evaluated and approved by the European Food Safety Authority (EFSA) through scientific studies:  

  • Vitamin D contributes to the normal absorption/utilization of calcium and phosphorus. 
  • Vitamin D contributes to normal calcium levels in the blood. 
  • Vitamin D contributes to the maintenance of normal bones. 
  • Vitamin D contributes to maintaining normal muscle function. 
  • Vitamin D helps maintain normal teeth. 
  • Vitamin D contributes to the normal functioning of the immune system. 
  • Vitamin D plays a role in the process of cell division. 

Your daily need for vitamin D 

The German Society for Nutrition e. V. sets a daily requirement of 20 µg per day. Adolescents and adults only consume an amount of 2-4 µg per day through food. The DGE recommends supplementation if there is no self-synthesis (especially in the winter months), as the intake of vitamin D through food is not sufficient to ensure the desired daily supply.  

Vitamin D is found in food, especially in fatty sea fish such as salmon, herring or mackerel. Eggs can also be a good source. Some mushrooms are grown under special conditions so that they can sometimes be rich in vitamin D. There is also margarine enriched with vitamin D. However, sufficient intake through food cannot be guaranteed. The main source remains the body's own vitamin D synthesis, which, however, requires sufficient sunlight.  

In our latitudes, sunlight is not sufficient for sufficient vitamin D synthesis, especially between October and Easter. In addition, we make it difficult for our bodies to have adequate contact with the sun's rays by wearing clothes and staying indoors, even in summer. Therefore, it is important (especially during the cold and dark season) to help our body to achieve or maintain a good vitamin D blood level through supplementation. Since vitamin D is fat-soluble, you should also consume a little healthy fat when taking vitamin D supplements for optimal absorption of the vitamin.  

Vitamin D can also be overdosed, but only through excessive intake of preparations and not through the body's own synthesis. Long-term intake of more than 100 µg per day can lead to an overdose. An overdose may result in elevated blood calcium levels, hypercalcemia, which may be associated with polyuria, constipation, muscle weakness, confusion and coma. It is therefore important to adhere to the recommendations when taking the preparations.  


How a vitamin D deficiency can manifest itself 

A vitamin D deficiency manifests itself physically primarily in a disruption of healthy bone growth. If the bones are not sufficiently mineralized during childhood, they remain soft and can become deformed. This also means deformations of the skeleton. This condition is known as rickets in children. Even in adults, demineralization due to vitamin D deficiency can lead to softening and deformation of the bones, a condition known as osteomalacia. This disease is accompanied by severe bone pain and muscle weakness. Another disease that can occur is osteoporosis. The bone mass is lower and the bones are slightly hollower and more porous on the inside, which leads to the bones becoming slightly brittle. A connection between vitamin D deficiency and non-bone-related diseases such as high blood pressure, diabetes, as well as cardiovascular or cancer diseases is currently being investigated.  

A link between the deficiency and neurocognitive disorders such as depression, anxiety disorders, dementia and ADHD is still under investigation.  

Which AgilNature products contain vitamin D? 





25 μg per daily ration (1 capsule each) 



5 µg per daily ration (2 capsules each) 


*Nutrient Reference Value = Percentage of the reference value according to Appendix XIII of the Food Information Regulation (EC) No. 1169/2011.  



  1. Vitamin D. DGE. (accessed on December 15, 2023) 
  2. Chang SW, Lee HC. Vitamin D and health - The missing vitamin in humans. Pediatric Neonatol. 2019 Jun;60(3):237-244. 
  3. Regulation (EC) No. 1924/2006 (Health Claims) 
  4. RKI - Gesundheit AZ - Answers from the Robert Koch Institute to frequently asked questions about vitamin D. (nd). (accessed on December 15, 2023) 
  5. Vieth R. Vitamin D supplementation: cholecalciferol, calcifediol, and calcitriol. Your J Clin Nutr. 2020 Nov;74(11):1493-1497. 
  6. DeLuca HF. Overview of general physiological features and functions of vitamin D. Am J Clin Nutr. 2004 Dec;80(6 Suppl):1689S-96S. 
  7. Vitamin D: How to take it correctly. Health Center. (accessed on December 15, 2023) 
  8. Rizzoli R. Vitamin D supplementation: upper limit for safety revisited? Aging Clin Exp Res. 2021 Jan;33(1):19-24. 
  9. Lewis, JL, III. (2023, October 26). Hypercalcemia. MSD Manual Professional Edition.  
  10. Roy NM, Al-Harthi L, Sampat N, Al-Mujaini R, Mahadevan S, Al Adawi S, Essa MM, Al Subhi L, Al-Balushi B, Qoronfleh MW. Impact of vitamin D on neurocognitive function in dementia, depression, schizophrenia and ADHD. Front Biosci (Landmark Ed). 2021 Jan 1;26(3):566-611.  
  11. Geng C, Shaikh AS, Han W, Chen D, Guo Y, Jiang P. Vitamin D and depression: mechanisms, determination and application. Asia Pac J Clin Nutr. 2019;28(4):689-694.  
  12. Akpınar Ş, Karadağ MG. Is Vitamin D Important in Anxiety or Depression? What Is the Truth? Curr Nutr Rep. 2022 Dec;11(4):675-681.  
Published on  Updated on