Vitamin D is a group of fat-soluble secosteroids necessary for the intestinal absorption of minerals such as calcium, magnesium and phosphate, and for many other biological functions. In humans, the most important compounds in this group are vitamin D3 and vitamin D2, which however will need to be mutated into calcitriol.
The main natural source of vitamin D is constituted by the endogenous production of cholecalciferol in the skin, starting from cholesterol, through a chemical reaction that depends on exposure to sunlight. However, cholecalciferol and ergocalciferol can also be taken with the diet and supplements, but only a few foods can be considered good sources of vitamin D.
An interesting article entitled Vitamin D Deficiency in Sports published on Praxis, deepens the topic: below you can read an abstract. "Vitamin D Deficiency in Sports Abstract. A deficiency in vitamin D is very common in the general population as well as in athletes.
The aim of this overview is to assess the level of knowledge about the importance of vitamin D for athletes. A deficiency in vitamin D is present in up to 90% of athletes. Risk groups are young athletes, female athletes, athletes with a limitation such as paraplegia, vegetarians, athletes with a resorption disorder such as celiac disease, athletes training and competing indoors (eg ice hockey, basketball, boxing, rhythmic gymnastics), and older athletes.
Dark skin pigmentation, the use of sunscreen, the time of day of the training (early morning, late evening) and the geographical location influence the risk for a deficiency in vitamin D. Exposure to the sun and a balanced diet are often not enough to prevent a vitamin D deficiency."
Omega 3: where to find it
Omega 3, whith Omega 6, are essential but we need to find it in the right food. Omega 3 needs for the protection of the circulatory system and for the prevention of cardiovascular diseases. The daily requirement of Omega 3 is, on average, about 3 grams.
Omega 3 is mainly contained in some types of fish, but we can find them also in some vegetables and legumes. Spinach, broccoli, lettuce and green cabbage, in addition to being very important sources of vitamins and minerals, also contain a small percentage of Omega 3.
Algae, very popular in Japan and other eastern countries, seaweed has now entered the market also in the West as an alternative food and with numerous nutritional virtues. Among these, there is also the richness of Omega 3.
About 30 grams of walnuts provide our body with almost 2 grams of alpha-linolenic acid (one of the fatty acids of the Omega 3 group). Linseed oil is by far the richest plant source in Omega 3 and the most useful for maintaining a balanced diet even excluding foods of animal origin.