Vitamin D is both a vitamin and a precursor of hormones often called a prohormone. The main forms that occur are vitamin D2 and vitamin D3, both of which differ in their source of origin. Vitamin D2 is produced by plants, while the body itself produces vitamin D3 by the presence of sunlight (UV). This explains why the vitamin D concentrations in our bodies gradually decrease during the dark winter months. We reach our lowest point in spring, just before the sun has enough power again to stimulate our vitamin D production. The amounts of vitamin D in our diet are usually too low to maintain our bloodlevels or to support any deficiencies.
Why is vitamin D so important to us?
Vitamin D is best known for its role in the absorption of calcium, which gives us strong bones. Yet this vitamin is involved in hundreds of processes in our bodies, including:
Vitamin D supports the production of the neurotransmitter serotonin, also known as the happiness hormone, which is important for our mental well-being. That is why there is a link between winter or spring depressions and vitamin D.
There is supposed to be a link between vitamin D and hypertension (high blood pressure) through regulation of the renin-angiotensin-aldosterone system. *
Via the transporter vitamin D has a modulating role on the innate and adaptive immune system.
There is supposed to be a link between vitamin D and various cancers such as breast cancer, colorectal cancer (colorectal cancer), etc. **
Vitamin D helps regulate the production of serotonin in the intestines. A lot of serotonin in the intestines can contribute to local inflammatory reactions.
The above non-exhaustive list thus underlines the importance of vitamin D for our health and performance.
Vitamin D and our genes
As we briefly mentioned above, our bodies produce vitamin D3 themselves under the influence of sunlight. This is an inactive form and must first be converted by our liver and kidneys to an active form. After conversion, a vitamin D transporter will ensure that the active vitamin reaches our vitamin D receptors. This receptor can be found in almost every body cell, which once again emphasizes the importance of vitamin D for our body.
The biological conversion of vitamin D3 to the active form 25-OH vitamin D3 is coded by the CYP2R1 gene in the liver. It is this 25-OH vitamin D3 that is monitored in a blood test.
Of the above mentioned gene, about 20% of the western population has a genetic variant that makes the conversion less efficient. The result may be that the vitamin D level in the blood rises much slower or hardly increases after supplementation or exposure to sunlight. People who have this genetic variant, will typically have to supplement with a higher dose of vitamin D to increase the blood value by the same number of points.
Analogously, there are several genetic variants that are relatively common in the transporter and receptor genes of vitamin D. Such a variant of the transporter or receptor gene can in some cases disrupt the effect of vitamin D somewhat. There are indications that higher blood values may be necessary in these cases to obtain a normal vitamin D activity.
Vitamin D is therefore crucial for your health in a lot of areas, because it is involved in many processes in our body. Having your vitamin D level in your blood checked and monitored is important on the one hand, because the levels in your blood can rise slowly. On the other hand, a prolonged large dose supplementation can lead to toxic values.