Spring is coming in a few days and finally the days are getting longer and brighter and warmer. There Sunlight brings with it numerous benefits: it makes us feel less tired and depressed, boosts our mental performance, improves mood and above all triggers increased production of vitamin D.
This vitamin has numerous functions in our body and generally the best known is the bone protection and prevention of rickets, a disease already known in the first century AD. C. in Rome. At that time, urbanization led to a decrease in exposure to sunlight, especially of newborns who were completely swaddled and taken very little outdoors. In the 90th century, according to studies from Leiden in the Netherlands, about 30% of children suffered from rickets characterized by bone malformations, muscle weakness and atonicity. It was observed that the cause lay in the lack of outdoor life and that some foods, such as cod liver oil, were able to prevent and cure this pathology. Some substance contained in the oil acted as an antirachitic factor and so this substance was considered to be another of the vitamins being discovered at that time. To distinguish it from vitamin A it was called vitamin D. We had to wait until the 70s to know its chemical structure and until the XNUMXs to understand the mechanism of activation of vitamin D, which by the way is not even a vitamin but is a prohormone.
Vitamin D is fat soluble, i.e. it is transported and absorbed with fats. The most important forms are D2 (ergocalciferol) of vegetable origin and D3, which is the most active form, (cholecalciferol) synthesized in animals starting from cholesterol. There are two sources of vitamin D: food and endogenous synthesis. Vitamin-rich foods are few: liver, wild fatty fish (herring, salmon, sardines), egg yolk, butter and milk (from grazing cows). Cooking does not decrease the availability of the vitamin which, like other fat-soluble vitamins, is quite thermostable. However, it is always advisable to cook the fish well to reduce the risk of Anisakis while for eggs, if they are fresh and especially from free-range hens, the best cooking is the one that allows you to keep the liquid yolk: soft-boiled, poached or bull's eye. Endogenous synthesis takes place in the skin where the precursor (dehydrocholesterol) absorbs radiant sunlight (mostly UVB) and is transformed into pre-vitamin D3, which is subsequently activated in the liver and kidney, becoming the active form, calcitriol.
Vitamin D needs two cofactors to play its role: magnesium and vitamin K2, so make sure that there are foods in your diet that contain enough of them: leafy greens, dried fruit, seeds, cocoa and fermented foods like sauerkraut or olives.
In recent years, studies have shown more and more often that a widespread deficiency of vitamin D has been established worldwide, according to the Italian Osteoporosis Society in Italy about 80% of people are affected by this deficiency. Indeed, the lifestyle we have adopted allows us to enjoy the outdoors very little. We are closed in the office or at school, we go to the gym indoors, we do the shopping and other errands using the machines and finally always go home indoors. On free days we often make up for part of our commitments and so relaxing in the sun becomes increasingly rare. In fact, we wait for the summer months to be able to go to the beach for two weeks but then we put on sunscreens which on the one hand protect the skin but on the other hand inhibit the production of vitamin D. It is calculated that a 15- 20 minutes a day in the central hours to produce a sufficient amount of the vitamin.
But why is vitamin D so important? This vitamin is essential for the maintenance of bone and dens healthti because it regulates the homeostasis of calcium and phosphorus, increases the renal reabsorption of calcium in the kidney and its deposit in the bones. Cholecalciferol stimulates the synthesis of the calcium transporter protein in the intestine (Calcium Binding Protein), thanks to which we can absorb this mineral that comes from the diet much more effectively. When vitamin levels are low and calcium absorption is inefficient, parathyroid hormone intervenes and regulates calcium levels by drawing it from the bones. A vitamin D deficiency in adults can induce or aggravate osteopenia and osteoporosis, or in more severe cases it can lead to osteomalacia, a form of rickets in adulthood.
It should come as no surprise that vitamin D has so many implications for our bodies, in fact cholecalciferol receptors are found in nearly every tissue. Countless research and publications show that vitamin D plays a very important role in the prevention of many diseases.
Studies prove that optimal levels of vitamin D have the protective role against tumors, in particular against breast, prostate, ovarian and colon cancers; the risk of getting sick is reduced by 60%. The active form of the vitamin, calcitriol, is known to be involved in the regulation of numerous genes, including those involved in cell proliferation and differentiation and apoptosis, this perhaps explains the link between its deficiency and cancer. The same also applies to hypertension and the risk of heart attack which, according to a vitamin D expert, M. Holick, increases by 50% in case of deficiency.
Recently, the Pathophysiology of autoimmune thyroid disease, adrenal disease, and hyperparathyroidism has been correlated with vitamin D deficiency. The active form of vitamin D is hypothesized to suppress autoimmunity in Hashimoto's thyroiditis. In fact it is able to modulate the immune system but does not suppress it (as happens with cortisone for example). It is still not entirely clear whether low cholecalciferol levels are the cause or effect of autoimmune diseases, surely they must be corrected with supplementation and increased sun exposure because optimal vitamin D levels improve symptoms and the antibody profile of diseases autoimmune and prevent chronic infections. Topical application of vitamin D has been shown to be linked to the reduction of acute and chronic inflammation in gouty arthritis with the reduction of swelling and pain in the acute phase.
Vitamin D deficiency has been associated with many dermatological diseases. Most sufferers of psoriasis, atopic dermatitis, rosacea and vitiligo have low or very low levels of the vitamin. One of the theories on vitiligo states that vitiligo is the cause of vitamin D deficiency and the white spots that form due to the destruction of melanocytes are nothing more than a way that the body has to expose as much surface as possible to the sun. Tanning actually decreases the production of vitamin D.
Vitamin D helps fight depression. In a recent study it was discovered that it stimulates the production of serotonin, a neurotransmitter that regulates mood, appetite, sleep and memory, it is no coincidence that it is called the "well-being hormone". Vitamin D activates other CNS neurotransmitters and counteracts inflammation. Human studies strongly support a correlation between low blood levels of vitamin D and cognitive impairment or dementia in aging populations. In parallel, animal studies demonstrate that vitamin D supplementation is protective against biological processes associated with Alzheimer's disease and improves learning and memory performance in various animal models of aging.
In addition to the diseases just mentioned, there are many other conditions with which vitamin D is associated, such as diabetes, chronic inflammatory diseases, obesity, menopause, etc. At this point, however, it is clear that maintaining serum levels of vitamin D is essential to stay healthy and to prevent a long series of diseases. It is worth doing a check to establish if you are lacking in order to intervene adequately. Increasing exposure to sunlight is fine but not always enough. Supplements can be taken to significantly increase the level of vitamin D. The most classic is Dibase but there are many others: in drops, tablets or soft gels; the important thing is to establish the dosage with your doctor (the ideal would be a daily dose because vitamin D has a half-life of 24 hours) and take it with fat, for example after lunch. To conclude, now that the beautiful days are ahead, let's take the opportunity to take a healthy load of vitamin D in the open air.
Happy Sun everyone
