Vitamin D

# What is vitamin D? Vitamin D is a fat-soluble vitamin and is primarily responsible for regulating calcium and phosphate metabolism for healthy bones, cartilage and teeth. Vitamin D is also involved in modeling the immune system and plays a major role in our mental state. Vitamin D is produced in the body with the help of sunlight in the skin and is also absorbed through foods such as fatty fish, eggs, mushrooms or avocado. 80% of the requirement is covered by the body's own production, absorption through food plays a subordinate role. Both endogenously produced vitamin D and vitamin D from food are activated in the liver to form 25-hydroxyvitamin D3 (calcidiol). Due to its stability, this form of vitamin D is a good marker for vitamin D levels. The next activation step takes place in the kidneys to form 1,25-dihydroxyvitamin D3 (calcitriol). This is the biologically active form of vitamin D, which finally binds to special vitamin D receptors and exerts an effect in the cells. Many steps in vitamin D metabolism can be significantly influenced by various gene variants, such as the function and activation of vitamin D receptors, activation enzymes or transport proteins. A vitamin D deficiency manifests itself in bone malformations, exhaustion, susceptibility to infections, frequent respiratory diseases, muscle weakness and depressive moods. ## Examples of foods rich in vitamin D: # What does genetics have to do with it? We are investigating three genes related to vitamin D metabolism: The GC gene (vitamin D binding protein gene) carries the blueprint for the vitamin D binding protein (DBP) in cells, which is responsible for the transport and storage of vitamin D in the body. Genetic variations of the GC gene can influence the amount and binding capacity of the vitamin D binding protein and affect the vitamin D level in the blood. - Variant rs2282679 of the GC gene: The genotypes G/T and G/G show a restricted function and reduced concentration of the vitamin D binding protein and a low vitamin D level. This condition is comparable to a vitamin D deficiency. The vitamin D deficiency is somewhat more pronounced in the G/G genotype. The DHCR7 gene (7-dehydrocholesterol reductase gene) carries the blueprint for the enzyme 7-dehydrocholesterol reductase in the cells. The enzyme plays a central role in the natural synthesis of vitamin D in the skin with the help of UV-B rays. Among other things, the enzyme converts 7-dehydrocholesterol into a type of vitamin D precursor, previtamin D3. Previtamin D3 finally reacts in further steps to form the active form of vitamin D (calcitriol). Genetic variations in the DHCR7 gene can influence the activity of the enzyme and impair the efficiency of the conversion processes and reduce vitamin D levels. - Variant rs12785878 of the DHCR7 gene: The G/T genotype shows a 1.2-fold increased risk of vitamin D insufficiency, the G/G genotype shows a 1.4-fold increased risk of vitamin D insufficiency. This means that vitamin D is present in an inactive state that cannot be used by the body.