Vitamin D protects against cancer, not just against rickets and osteoporosis, as shown by numerous recent research. Among the new findings about the so far completely underestimated importance of vitamin D the scientists could Dr. med. Jörg Reichrath (Department of Dermatology) and Dr. med. Michael Friedrich (gynecological clinic) of the university hospitals of Saarland in Homburg contribute significantly.
Vitamin D: effect and importance for health prophylaxis
Vitamin D, commonly known as the "sunshine vitamin", is not a vitamin in the true sense, but a hormone. The term vitamin was mistakenly attributed to him, after it was discovered very early that this substance contained in cod liver oil can prevent or cure rickets in children.
Vitamin D deficiency is widespread and underestimated in its incidence, but also in its consequences for health. A severe vitamin D deficiency is common in winter. The most important reason for this is the relatively low UV radiation in our latitudes, so that between October and March often too little vitamin D is formed in the skin. In spring and summer, direct contact with the sun is often avoided because of the risk of skin cancer - a real dilemma, as up to 90% of the vitamin D required is formed in the skin using the sun. Even the UV-A light used in tanning salons does not lead to vitamin D formation in the skin. The ability to absorb vitamin D via food is very limited: In addition to cod liver oil, vitamin D is only found in a few other foods, such as the meat of some fish species (eg salmon and mackerel). Therefore, there is often only the pharmacological substitution.
Risk groups for vitamin D deficiency
In general, all population groups are affected by the vitamin D deficiency. However, a particular health risk is mainly due to older people and people with more skin pigmentation. In both groups, the ability to produce vitamin D in the skin is relatively low. Infants and young children are also at considerable risk. This problem seems to be exacerbated, especially in populations with darker skin color. Suffering breastfeeding mothers with severe vitamin D deficiency do not have adequate vitamin D levels in breast milk. Obese people also often suffer from vitamin D deficiency and, consequently, secondary hyperparathyroidism (parathyroid hyperactivity) and osteomalacia (bone mineralization defect). The reason for this is the high content of body fat, which binds vitamin D, a fat-soluble hormone, very efficiently and thereby removes it from the blood.
Vitamin D protects against cancer
Recent results show that the biologically active form of vitamin D, the 1, 25-dihydroxyvitamin D, is not only produced in the kidney, but also in a whole range of different tissues. In these tissues, 1, 25-dihydroxyvitamin D regulates cell growth locally via autocrine / paracrine mechanisms via binding to specific nuclear receptors. On the one hand, this inhibits cell proliferation, on the other hand it induces cell maturation. Recent findings suggest that these mechanisms prevent carcinogenesis in many tissues. A whole series of studies confirm the connection between vitamin D deficiency and colon, prostate and breast cancer: these cancers occur significantly more frequently at higher latitudes, ie where less vitamin D is also formed in the skin due to lower solar radiation, In addition, studies show that with sufficient vitamin D intake (ie, the main metabolite 25-hydroxyvitamin-D has a blood concentration of> 20 ng / mL), the risk for different cancers (including colon cancer) is significantly reduced.
The fact that most body tissues not only recognize 1, 25-dihydroxyvitamin D via their own receptors, but also have the enzymatic capacity to form them (from 25-hydroxyvitamin D), suggests that vitamin D is a key hormone with a protective effect even in other diseases. For example, studies show a significance of vitamin D deficiency associated with type I diabetes, multiple sclerosis and rheumatoid arthritis. Here, a central importance of 1, 25-dihydroxyvitamin D for the immune system is discussed.
The protective role of vitamin D also plays an important role in many tissues to prevent aging processes, including in the skin against UV-related damage. Thus, vitamin D analogues are promising substances for use in "anti-aging therapy".
Vitamin D deficiency and its far-reaching consequences
New findings in the field of vitamin D research show the importance of adequate vitamin D supply for health. Chronic vitamin D deficiency leads to a mineralization defect in the bone: rickets in children, osteomalacia - also known as adult rickets - and osteoporosis (loss of bone mass) in women and men are the consequences. The incidence of osteoporosis has increased dramatically in recent decades. Research shows that 50% of all women, but also 12% of all men experience an osteoporotic fracture during their lifetime. In the prophylaxis and treatment of osteoporosis, it has been repeatedly shown that the connections between osteoporosis and vitamin D deficiency are not sufficiently known. Frequently, care is taken in this context only on an improved calcium supply. It is forgotten that optimal calcium absorption in the intestine can take place only with sufficient vitamin D supply. Vitamin D deficiency is often diagnosed as a weakening of the muscles and muscle pain. In studies with vitamin D substitution in the elderly, it could be shown that an adequate vitamin D supply increased the muscle tension. It has also recently been shown that vitamin D analogues can lower elevated blood pressure levels.
Vitamin D status: How much vitamin D does a person need?
Vitamin D deficiency can be detected by measuring 25-hydroxyvitamin D in the blood. The standard ranges are given in the literature as approx. 10-60 ng / mL. Values below 10 ng / mL must be classified as severe vitamin D deficiency. However, recent studies show that even at levels between 10 and 20 ng / mL must be spoken of a vitamin D deficiency, since in these cases often makes an overactivity of the parathyroid gland noticeable. For 25-hydroxyvitamin D, 20 ng / mL should be considered as a minimum with regard to bone health. To prevent cancer, a minimum of 25-30 ng / mL is now recommended by various experts. The use of vitamin D as a dietary supplement (eg milk) also makes sense. For this, however, the legal requirements are currently missing in Germany. If a vitamin D substitution is required, a target range of 25-45 ng / mL should generally be targeted. Here, a double control measurement per year is recommended.
Outlook - Perspectives of a Pharmacological Use of Vitamin D
Due to their growth-inhibiting effect in dermatology, vitamin D analogues have been successfully used for many years for the external treatment of many diseases such as psoriasis. So far, however, an internal treatment (eg tablet administration) of these drugs has only been possible to a very limited extent because of the occurrence of side effects (in particular on the calcium metabolism). However, recent research results have led to the development of new vitamin D analogues with a significantly more favorable effect / side effect profile. Initial clinical results indicate promising prospects for the therapeutic use of these drugs in many cancers.