Vitamin D Through the eyes of an expert

You often ask us what’s the real deal with vitamin D or with, for instance, iodine. We chose your most frequently asked questions and asked an expert, Mudr. Petr Tláskal, CSc. Doctor Tláskal is chairman of the board of the Society for Nutrition, he is also the chairman of the Nutrition Team and an institutional dietitian at the Faculty Hospital in Motol. He is an expert on losing weight, and his primary focus is paediatric obesity.

How big of a role does vitamin D play in the immune system?

In addition to its other functions in the body, in terms of immunology, vitamin D primarily impacts cell activity. Immunologist Professor Krejsek states that vitamin D plays a primary function in maintaining the stability of immune reactions and a vitamin D deficiency can increase (in sensitive individuals) the risk of developing immuno-pathological diseases (such as multiple sclerosis). 

Is vitamin D obtained through diet more suitable/effective than vitamin D created in the body from sunlight?

Effective forms of vitamin D are created following exposure to sunlight in concordance with the proper function of the kidneys and liver. Additionally, vitamin D obtained orally must be properly absorbed from the digestive tract. This can be a problem for people that have what is called called “malabsorption syndrome”, i.e. a disorder in digestion, absorption, or secretion into the digestive tract. Furthermore, vitamin D is fat-soluble.  Therefore the usability of vitamin D from foods can be somewhat complicated.

What are the possible consequences of an iodine deficiency?

Iodine is a primary part of thyroid hormones. A deficiency can result in the formation of an endemic goitre with symptoms of an under-active thyroid (in pregnancy this can result in the delayed development of the embryo and its mental functions, in older individuals it can result in greater fatigue, sensitivity to the cold, greater weight gain, poorer bowel movements, etc.).


Vitamin D is important to people of all age categories.  A vitamin D deficiency at a young age leads to rickets, in later stages it can lead to osteoporosis with increased bone brittleness. We focus on vitamin D consumption most often in early childhood, during pregnancy, for senior citizens, and generally in people who limit or need to limittheir exposure to sunlight.