Vitamin D… the vitamin that is not a vitamin!
Let’s go to the discovery of Vitamin D with the nutritionist Simona DiPirro: first appointment on Capital with the column dedicated to Welfare… which also includes food.
A bit of history – In the first half of the last century, the American biochemist McCullum identified inCod liver oil a fat-soluble principle that was able to counteract rickets, a pathology that determines the development of little mineralized and deformed bones in children and to which he gave the name of Vitamin Dfollowing the alphabetical order of the vitamins known until then.
Today we know that vitamin D, or rather D3, is synthesized in our body from molecules present in food or generated directly in our skin, to photosynthesis. We actually call vitamin D3 a number of different chemical compounds that are similar to each other, but differ in biological activity. Vitamin D3 acts like a hormone and does its job in many tissues such as intestine, heart, brain, muscle, gonads, breast, prostate and cells of the immune system, not just in the bone! Furthermore, it should not be forgotten that it is also capable of activating the transcription of about a hundred genes. It is easy to understand why today many studies on autoimmune and oncological diseases include the dosage of vitamin D3.
The fundamental role of vitamin D3, therefore, is not to fix calcium in the bones, but to stimulate the absorption of calcium in the intestine.
Where can we find vitamin D?
In algae, in some fatty fish such as herring, wild salmon, in chicken eggs (especially in the yolk), in meat (depending on the type of cut), in liver, in oysters and prawns, in butter and in mushrooms, in which ergosterol is present which, following solar radiation, is transformed into vitamin D2.
Good! After all, it would seem easy to fill up on vitamin D… ma unfortunately this is not the case. In fact, intestinal absorption is minimal (20%) and the production derived from sun exposure is not sufficient during the winter. Very often I see people with vitamin D levels below the threshold of sufficiency (30ng/ml) who need targeted integration!
Now let’s answer some questions from our readers.
- Is it true that vitamin D causes kidney stones?
Although some studies have found higher vitamin D levels in people with kidney stones, there are actually no studies that show a definite correlation between vitamin D intake and their formation. However, it is advisable to monitor calcium levels in case of supplementation.
- How many times a month should I take vitamin D?
Vitamin D should be taken daily in the recommended dose and adapted to the patient’s personal situation.
- Is vitamin D useful against SARS-CoV-2 infection?
Many studies have now confirmed the association between severe disease and hypovitaminosis (insufficient amount of vitamin in the body), but the effective effectiveness of supplementation once the disease has been contracted is still being studied.
Let’s take a closer look…
How does Vitamin D work?
1,25-dihydroxy-vitamin D, which we find on the reports of our blood tests with the initials 1,25(OH)D, is the biologically active metabolite that is obtained following a complex metabolic process involving various organs and anatomical regions (skin, blood, liver, kidney, adipose tissue, intestine).
The fundamental role of vitamin D3, we said, is to stimulate the absorption of calcium in the intestine, but the blood balance of this ion also depends on the action of two other molecules, parathyroid hormone (PTH) and calcitonin (CT ).
PTH is a hormone produced by the parathyroid glands which ensures stable calcium levels through a direct action at the bone and kidney level and, through an indirect action, at the level of the intestine via vitamin D3.
Calcitonin is produced by the thyroid and parathyroid glands and has an opposite effect, lowering blood calcium levels.
But practically what happens?
-When blood levels of calcium decrease, the PTH which acts both at the bone level, solubilizing the matrix and thus releasing the calcium, and at the renal level, inducing the synthesis of vitamin D3, which, at the intestinal level, promotes the absorption of the calcium itself.
-On the other hand, when blood levels of calcium increase, calcitonin stimulates both bone formation and renal excretion of calcium and the inactive form of vitamin D, which therefore cannot act in the intestine.
We understand now why to win our daily race against disease and be in good health it is necessary that all players on the team are present in the right quantities and are able to work together.
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The Dr. Simona Di PirroNutritionist biologist, will be a guest of “The capital” with its fortnightly column. You can suggest topics or ask questions by writing to the editorial board of the capital. Dr. Di Pirro graduated with honors from the University of L’Aquila in Biology of Health and Nutrition, attended the advanced training school in Mycotherapy (use of medicinal mushrooms) at the University of Padua and the high school training in human microbiota in collaboration with the University of Pavia. She is also a consultant for food hygiene and management of the HACCP system.
The doctor offers her patients a nutritional approach based on functional medicine at his studios in L’Aquila and Avezzano.
These are his social references:
-facebook page: Dr. Simona Di Pirro Biologist Nutritionist
-instagram: simonadipirronutrizionista