The sun, which enables us to live on earth every day, is not only a life-giving source of heat and light, but also the supplier of an essential nutrient for our bone health: vitamin D3.

In this article, we delve into the fascinating world of the “sunshine vitamin” and explore its crucial role for strong bones, an efficient immune system and our emotional balance.

What is vitamin D3?

Vitamin D3, commonly known as "vitamin D" and scientifically known as cholecalciferol, is a subtype of vitamin D that is naturally produced in the human body and plays a central role there. Vitamin D is just a generic term for fat-soluble vitamins.

Vitamin D occurs in two forms in foods: as ergocalciferol (vitamin D2) in plant foods (e.g. chanterelles) and as cholecalciferol (vitamin D3) in animal foods (especially in oily fish).

However, most of the vitamin D3 in our body does not come from food, but from somewhere else entirely - the sun, at least indirectly. The sun does not provide us with immediately available vitamin D3, but ensures that it is synthesized as a reaction of our skin to contact with the sun's UVB radiation.

And how exactly does it work?

The sun's UVB rays convert 7-dehydrocholesterol, which is found in our skin, into vitamin D3. After synthesis, vitamin D3 is transported to the liver, where it is converted into the active form, calcidiol.

It is then further converted in the kidneys into the biologically active form, calcitriol. Calcitriol regulates the calcium and phosphate balance in our body by increasing the absorption of calcium in the intestine and inhibiting the breakdown of bone tissue.

The biological function of vitamin D3 is therefore closely linked to our calcium metabolism and bone health. It also plays a role in muscle contraction and influences various cellular processes in our body.

Both endogenous synthesis through sun exposure and intake through food and dietary supplements help maintain adequate vitamin D3 levels in our organism.

Before we go into more detail about the biological functions of vitamin D3, we have summarized five (not so funny) fun facts about vitamin D3 to give you a taste of the integral importance of the sunshine vitamin.

5 (Not so) Fun Facts about Vitamin D3

• Vitamin D deficiency worldwide: Despite its importance, vitamin D deficiency is widespread throughout the world. This is due to several factors, including inadequate sun exposure, certain diets and age-related skin changes.

• Sunscreen and synthesis: Wearing sunscreen reduces the production of vitamin D3 because UVB rays are blocked. However, protection against skin cancer is important and requires a balancing act from us.

• Vitamin D3 and diabetes: There is evidence that inadequate vitamin D3 levels can affect the risk of diabetes. Studies show links between low vitamin D levels and an increased risk of diabetes.

• Seasons affect synthesis: The amount of available sunlight varies with the seasons. In regions with limited sunlight, vitamin D3 supplementation may be necessary in winter.

• Vitamin D3 is hardly found in food: Vitamin D3 is found in only a few foods, and in most foods only in small amounts. In addition, this vitamin is fat-soluble, so its efficient absorption in the intestine requires the presence of sufficient amounts of fat. People on low-fat diets or with digestive disorders that impair fat absorption may therefore have additional difficulty meeting their vitamin D3 requirements through their diet.

What role does vitamin D3 play in our body?

Consequently, we would now like to take a closer look at the various biological functions of vitamin D3 for our general health.

Vitamin D3 for healthy bones — The key to calcium absorption

As mentioned above, vitamin D3 plays a key role in regulating calcium and phosphate levels in the body. This mechanism is crucial for the mineralization of bones, which in turn supports their structure and strength. Vitamin D3 gives us our backbone, so to speak.

A lack of vitamin D3 can lead to inadequate calcium absorption, which increases the risk of bone diseases such as osteoporosis. The path to strong bones is therefore through the efficient absorption of calcium.

But how does vitamin D3 do this?

By stimulating calcium transport proteins in the intestine, vitamin D3 helps this essential mineral to be better absorbed and incorporated into the bones. It is not only important to consume enough calcium, but also to ensure that the body can use it optimally.

Vitamin D3 therefore acts as a key that opens the doors for calcium and thus lays the foundation for strong, resilient bones.

Vitamin D3 for muscles and coordination

Vitamin D3 also plays a central role in muscle function by regulating muscle contraction and coordination. Studies have shown that people with low blood levels of calcidiol fall more often than people with sufficient blood levels.

If vitamin D3 binds to muscle receptors, it supports strength development and helps prevent muscle weakness. A sufficient vitamin D level is therefore crucial for the health and performance of our muscles.

Vitamin D3 to strengthen the immune system

But the effect of vitamin D3 is not limited to our bones. It also acts as an invisible shield that strengthens our immune system.

Studies show that adequate vitamin D levels are associated with a lower susceptibility to infections and inflammation, a protective mechanism that ranges from warding off colds to more serious illnesses.

In times when our immune system is particularly challenged, it becomes clear how vitamin D3 acts as a natural enhancer that increases our body's resistance to disease.

Vitamin D3 for mood improvement

The sun makes many of us feel better — and this is scientifically proven. Vitamin D3 plays an important role in this effect.

Studies show that vitamin D3 plays a role in regulating neurotransmitters in the brain, especially those related to mood. So the happy mood you get when you're out in the sun might be down not only to the beautiful golden rays of the sun, but also to the vitamin D3 that they synthesize.

Conversely, a deficiency in vitamin D3 can lead to low serotonin and dopamine levels, which in turn are associated with mood problems such as depression.

This phenomenon is strongly associated with the so-called winter depression.

Sources of Vitamin D3 – Sun and Supplements

The crucial question now is: How can we ensure that we get enough vitamin D3?

The main source of vitamin D3 is the sun. When our skin is exposed to sunlight, the body begins to produce vitamin D3. However, factors such as skin type, season and geographical location are crucial for the synthesis, which is not always possible for all of us.

In Switzerland in particular, there is a long winter, where the sun sometimes does not appear for a long time and sufficient synthesis of vitamin D3 through sunlight is hardly possible.

Supplementing vitamin D3 therefore makes a lot of sense in this country to ensure an adequate supply of this important vitamin.

Can't you get vitamin D3 through food?

As one of our "Fun Facts" has already mentioned, vitamin D3 is only found in small amounts in our food. Many foods contain only trace amounts of vitamin D3, especially if they are of plant origin, since the synthesis of this vitamin is closely linked to animal tissue.

Oily fish are the exception and a fairly good source of vitamin D3, but even these are not part of most people's everyday diet to adequately cover their needs.

For those who live in regions with little sun or who have difficulty spending enough time outdoors due to their job, dietary supplements can therefore be a useful addition.

Interestingly, the Yale School of Medicine has even announced that vitamin D3 from supplements is equivalent to vitamin D3 synthesized by the sun.

And what should a good vitamin D3 supplement or dietary supplement look like?

Vitamin D3 Supplements – Quality is of Integral Importance

A high-quality and bioavailable vitamin D3 supplement should contain a form of cholecalciferol, the natural form of vitamin D3. It is also beneficial if the vitamin D3 is provided with high-quality carrier oils such as fish oil to support fat solubility in the intestine. The combination of vitamin D3 and vitamin K2 (especially in the form of menaquinone-7, also known as MK-7) is recommended because they have synergistic effects on bone metabolism and other physiological processes in the body.

Dosage should be based on individual needs and in accordance with the recommendations of healthcare providers.

We can conclude that vitamin D3 is not only the “sunshine vitamin” for strong bones, but also a crucial player for a functioning immune system, healthy muscles and a bright mood.

By consciously integrating sunlight and high-quality vitamin D3 supplements, we can ensure that our body benefits optimally from the advantages of this vital nutrient – ​​in our latitudes all year round, but especially in the winter months.

Please note that it is important to consult a healthcare professional before taking any dietary supplements or making any changes to your diet. The information in this blog is intended for general information purposes only and is not a substitute for professional medical advice.

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