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Vitamin D3: How to use the energy of the sun all year round

Vitamin D3: How to use the energy of the sun all year round

Vitamin D3: How to use the energy of the sun all year round


Vitamin D3 is essential for the human defense system to function normally. In case of a deficiency, our immune system is weakened and we run the risk of getting sick faster. That is why colds occur very often, especially in February and March, when vitamin D stores are depleted. Other important functions of the vitamin are the maintenance of bones, teeth and muscle function. In addition, vitamin D contributes to the normal absorption and utilization of calcium and regulates the calcium level in the blood!

One thing quickly becomes clear: the body can’t anything do without the sun vitamin!

The vitamin D formation and absorption

Vitamin D is actually not a vitamin at all, but a prohormone. This means that it is the precursor of a hormone that is first converted into an actively active hormone in the liver and kidneys as well as in various cells. This conversion always takes place by the organism, regardless of whether the vitamin D3 is produced with the help of sunlight or supplied via a dietary supplement.

Only a small part of vitamin D3, also known as cholecalciferol, is absorbed by the human body via vitamin D-containing animal products. The majority, around 80 to 90%, is produced by the human body on its own by converting cholesterol into vitamin D with the help of sunlight. The cholesterol is converted into vitamin D3 in the skin under the influence of UVB radiation [1,2].

The key function for the immune system

Research has shown that vitamin D serves as an important messenger in the control of the immune system. It influences both our innate and adaptive (acquired) immune systems. Each individual immune cell has vitamin D receptors on its surface and is able to convert vitamin D to the active form when needed. Vitamin D regulates the immune system so that pathogens are fought early and no physical reaction, such as a cold, occurs in the first place [3]. Human T cells, which recognize and kill pathogens, are activated by the vitamin so that pathogens are blocked. Thus, vitamin D supports the body's defenses, which protect humans from viruses and bacteria [4,5]. Defenses that protect against fungi or cancer cells, such as cathelicidin, are also supported by the vitamin in production [6,7,8].

For these reasons, vitamin D deficiency should be prevented at all costs, as otherwise autoreactive T cells are formed which attack the body's own cells and, in the worst case, even cause an autoimmune disease. Since vitamin D prevents the body from attacking itself because it cannot distinguish between its own and foreign cells, the vitamin is also known as an immunomodulator [9,10,11].

The support for infections

The importance of an adequate vitamin D supply has also been proven by numerous studies. An Italian research with 42 test persons showed that about 81% of the COVID-19 patients suffer from a vitamin D deficiency. Here, patients with acute vitamin D deficiency (below 10 ng/ml) had a 50% risk of death. When the vitamin D level of SARS-CoV-2 infected individuals was above 10 ng/ml, the risk of death was only 5% and thus 10 times lower [12]. Various studies have also shown that an adequate supply of vitamin D has a positive effect on the course of influenza [13,14,15,16].

Here it is important to emphasize that vitamin D is not a cure for corona or other infectious diseases. However, a sufficient supply is a good prevention to protect the body.

Too little sun = too little vitamin D

In Germany, about 60% of the population has a vitamin D deficiency. A D deficiency means that the body has less than 20 ng/ml of the vitamin in the blood serum [17]. Due to our geographic location and modern lifestyle, this is not surprising.

In order for vitamin D to form in the skin, it needs sunlight. Important to know: the wavelength of the light is of crucial importance. UV-B rays with a wavelength of 290 to 315 nm are needed for D production, which varies greatly depending on geographic location and especially on the time of year. Particularly in the dark season, vitamin D deficiency can therefore occur quickly.

The ozone layer in the stratosphere fulfills its protective function by not allowing high wavelengths of light 200 to 280 nm (UVC) and UV-B components above 290 nm to pass through. Of the UVB radiation of wavelengths above 290nm, only about 1% passes through the ozone layer, so we only have the opportunity to absorb 1%.

The challenge: especially for countries in the northern hemisphere, this 1% can only penetrate between 10 a.m. and 3 p.m., and only during the months of April to September. This is because it is only during this period that the angle from the earth to the sun is short enough for the light quanta to reach a UV index of 3. Anything below a UV index of 3 is not sufficient to produce vitamin D [18,19]. Also a challenge to D intake, most people are indoors at this time of day.



How much vitamin D does a person need?

The unit of measurement IU (International Unit) is used as the standard unit when speaking of the amount of vitamin D. It is important to know:

1 IU is equivalent to 0.025 micrograms (μg)

There is no international guideline value for the daily requirement from the German Nutrition Society. Especially in the dark months, when the organism cannot produce the vitamin on its own, up to 5000 IU can be supplied daily. In order to find an optimal dosage for oneself, it is worthwhile to have a blood test to determine the appropriate, individual dosage under medical supervision. But even among doctors there are different opinions about which value is optimal. Too low a D level can demonstrably be detrimental to health. Now the question arises: what daily intake is healthy and sufficient?

Numerous sources define a D level between 40 and 60 ng/ml in blood serum as ideal. Values up to 60 ng/ml are considered safe in conventional, general medicine [20].

In order to benefit from the positive effects of the vitamin, experts recommend an equal-dose, permanent supply instead of a weekly or monthly overdosed cure. After all, our body does not produce extremely high doses at once in sunny weather, but rather the required amount every day in order to be protected.

Primitive people provide the answer

Since the human organism is self-regulating, no overdose has ever been proven by the body's own production of a healthy person. For this reason, some physicians use primitive peoples, i.e. people who still live under pristine conditions, as a reference. Here it is to be investigated whether an overdose of the fat-soluble vitamin D3 is possible. In these people, who live at the height of the equator, a healthy vitamin D level of 50 to 90 ng/ml could be detected [21].


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 Attention: No D3 without K2

For vitamin D to work safely and reliably, D alone is not enough. As already mentioned above, vitamin D is significantly involved in the control of calcium absorption and is also responsible for the synthesis of some important proteins. For these proteins to become active and exert their effect, vitamin K2 is important as a co-factor. Only in combination with K2 can the absorbed calcium be properly transported and utilized. Thus, two of the most important human proteins, the matrix GLA protein (MGP) and osteocalcin, have also been shown to be dependent on vitamin K2 [22,23,24,25].

The influence of vitamin K2

The protein osteocalcin is important for the formation of new bone. It ensures that the absorbed calcium is incorporated into the bones. Matrix GLA prevents calcium from accumulating in organs or vessels by binding the calcium and transporting it away [26]. If vitamin K2 is not present for this process, the proteins cannot act and there is a risk that the calcium will lead to calcification in the vessels and organs. Thus, kidney stones, arteriosclerosis, and numerous diseases, including myocardial infarction, are favored [27]. In addition, if calcium accumulates in the wrong places, it cannot fulfill its functions for bone health.

The right amount of K2

If vitamin D levels are high, vitamin K2 deficiency can quickly occur because K2 is also consumed for vitamin D activation. In this case, vitamin K2 can no longer be used for the other processes in the body described above [28]. Calcium in this case, even though the level in the blood is not too high, can be deposited on the vessels and organs due to the lack of vitamin K2 for utilization [29,30,31]. This is also partly the reason for the toxic effect of vitamin D in very high amounts.

Animal studies have shown that vitamin K2 deficiency can cause symptoms similar to those caused by a toxic, extremely high dose of vitamin D [32]. It is therefore not surprising that high vitamin D levels, which are normally good for bones, can increase the risk of bone fractures if vitamin K deficiency is also present [33].



Remember: When taking 1000 IU of vitamin D, always take at least 50 micrograms of vitamin K2 in parallel.


The functions of K2

Vitamin K2 is involved in numerous bodily functions. The vitamin is found exclusively in animal and fermented foods.

In the body it influences the proteins osteomalacia and matrix GLA and is also involved in processes in the liver. Also, K2 activates the gene Gas6 (Growth-Arrest-Specific-Gene-6), which participates in cell division and cell locomotion in vessels and organs [34,35].

In addition to its positive influence on bones, vessels and skin, vitamin K2 also has anti-inflammatory properties [36]. And the human brain also has an increased K2 concentration. Here, the vitamin contributes to the formation of protective compounds [37]. To simply explain the importance of the vitamin again: If a vitamin K2 deficiency occurs, there is a higher risk of dying from heart failure. This risk is as high as in people who smoke heavily and are also prone to heart failure [38,39].

Furthermore, the latest research shows that an adequate K2 supply should also be ensured in chronic kidney disease [40].

The differences in vitamin K2 form

Vitamin K has different forms, but their effects are quite similar. The number designation is based on the number of chemical side arms which range from MK4 to MK13. The most widely studied forms are MK4 and MK7.

The MK7 form accumulates most effectively in the body, providing a sustained and adequate supply to all organs and tissues. By comparison, while MK7 remains available in the blood for more than 72 hours (half-life), the majority of MK4 is excreted after only about 1.5 hours. In addition, MK7 is significantly more effective than the MK4 form. Around 60 µg of MK7 show a better effect than a whole 500 µg of MK4 [41,42,43,44].

As with many molecules, there are two different forms of vitamin K2 MK7: the cis and trans form. These isomers have the same number of atoms, but a different spatial structure. Only the trans form of vitamin K2 MK7 can be utilized by the body. The cis form is ineffective for it! Unfortunately, many vitamin K2 products consist of up to 70 percent of the cis isomers.

A high-quality vitamin K2 dietary supplement should therefore always have the designation all-trans MK7!

Magnesium - an indispensable partner

What many people do not know: a magnesium deficiency can limit the effect of vitamins!

As already mentioned, vitamin D3 must first be converted by the body in order to work. The enzymes needed to do this, as well as the transport molecules that distribute vitamin D throughout the body, rely on magnesium. The parathyroid hormone (PTH) produced in the parathyroid gland, which regulates D conversion, also requires magnesium.


In Germany, 26% of men and 29% of women do not consume the daily recommended D-A-CH reference value of magnesium [45].


A high intake of vitamin D can therefore also lower magnesium levels, since significantly more is consumed for D activation. Regardless of whether vitamin D is taken from the sun or in the form of vitamin D supplementation, without magnesium, vitamin D can never develop its full effect and an overdose can even be harmful [46,47,48,49,50,51].

Since all known enzymes in vitamin D metabolism require magnesium, care should be taken to ensure an adequate supply.

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Study shows: Liposomal vitamin D3 + K2 has higher bioavailability.

Recent research shows that vitamin D3 packaged in liposomes guarantees 13x higher absorption than conventional tablets.


Since D is a fat-soluble vitamin, vitamin D intake can become a challenge. Influencing factors such as the individual, human fat digestion or but the stomach contents can therefore lead to restrictions in vitamin D intake. The liposomal form ensures a consistent, unrestricted supply in daily intake. The K2 used by ActiNovo is also the active MK7 all-trans form, which has a sufficient ratio of 75 µg all-trans MK7 K2 to 1000 IU = 25 micrograms vitamin D3! With the supplementation of the mineral magnesium, the vitamin D preparation can develop its full effect.

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