Vitamin D

Have you also felt a gentle hint of spring? 

Admittedly, this weather will only last for two more days, but I think it's a good time to write a few words about vitamin D, also known as the sunshine vitamin. What functions does it perform in our body, how much should we take and what is the best way to take it, what are its sources (including for vegans), and what is the actual requirement for it in sports?

The term "vitamin D" refers more precisely to two compounds: vitamin D2 (ergocalciferol), found in plant products, mushrooms, and yeast, and vitamin D3 (cholecalciferol), found in animal-based foods.

From the outset, it has been an interesting phenomenon for scientists because its structural composition resembles testosterone. Therefore, VITAMIN D can be considered a prohormone. 

FEATURES

Vitamin D has many functions, which confirms how important it is for us. 

1. It is now known that vitamin D affects more than just the skeleton. Its active forms are also found in cells that are not involved in regulating calcium and phosphate metabolism. However, for it to be activated (this applies to both types of vitamin), the liver and kidneys must be functioning properly. Vitamin D deficiency is often the primary cause of bone decalcification, as it is responsible for the proper absorption of calcium. As a result, it causes bone, joint, and muscle pain.
   
   
2. In addition, it protects the body from infection, so low levels can lead to poor health.

3. It has been suggested that vitamin D supplementation reduces cardiovascular risk through various mechanisms. One of the most important is the reduction of renin secretion by inhibiting its gene expression, which lowers the activity of the RAA system. 

4. Vitamin D supplementation has been proven to reduce the risk of type 1 diabetes in children by a factor of 8.
   
   
5. A lower risk of metabolic syndrome and insulin resistance has been demonstrated in people with adequate levels of this vitamin. In addition, normal serum concentrations are thought to delay the development of type 2 diabetes in people with abnormal fasting glucose levels. 

There are many other reasons that make taking vitamin D a must, but I encourage you to read articles/books on this topic.

DOSAGE

Let me start by saying that vitamin D intake in the general population should be individualized depending on:
- age,
- body weight,
- sun exposure (season),
- diet,
- lifestyle.

However, I will focus on adults whose physical activity is low or moderate, as well as athletes.
For healthy people who have the opportunity to spend at least 15 minutes in the sun between 10 a.m. and 3 p.m. without sunscreen from May to September, supplementation is not necessary!
However, if the above conditions are not met, supplementation at a dose of 800–2000 IU/day is recommended, depending, of course, on body weight and vitamin D intake from the diet, throughout the year.

Vitamin D is used in every sport. For people who practice competitive sports, the recommended doses range from 2,000 to even 10,000 IU per day.

During vitamin D supplementation and treatment, it is important to ensure an adequate supply of calcium in the diet.

SOURCES 

The main products that contain significant amounts of vitamin D are: fish oils, fatty fish, cheese, eggs, milk, and liver. 

While it is easy to obtain vitamin D in the form of ergocalciferol in a plant-based diet by consuming phytoplankton, mushrooms, and yeast, it can be more difficult in the case of cholecalciferol. Vegan athletes who live in countries where the sun shines all year round are not as prone to vitamin D3 deficiency. However, this does not mean that they should not supplement their diet with this vitamin. On the other hand, athletes who train in areas with low sun exposure must take supplements and consume foods fortified with vitamin D3. In the past, it could be difficult for vegans to find the right supplement, as many of them are of animal origin. Nowadays, vitamin D3 can be obtained from lichens and mushrooms that have been exposed to ultraviolet radiation.

All these factors are extremely important not only for amateur athletes, but also for professional athletes. That is why it is worth knowing a few basic facts about VITAMIN D.

Article based on:

- my bachelor's thesis "The use of a vegan diet in CrossFit training"
- VITAMIN D SUPPLEMENTATION AND TREATMENT GUIDELINES – 2018 UPDATE; AGNIESZKA RUSIŃSKA1†, PAWEŁ PŁUDOWSKI2, M, MIECZYSŁAW WALCZAK3, A ,G, MARIA et al.
- Vitamin D - its role and importance for the body Beata Kaźmierska, M.Sc. in Pharmacy Review paper as part of a specialization in pharmacy

‍