"Stay in the sun for a while so take vitamin D": How many times have you heard yourself make this recommendation?
Maybe you take the importance of this vitamin for granted, but do you really know how much your health depends on its good supply?
In this article I would like to talk about how we take it, how it works and above all in which biological processes is fundamental.
- 1 WHAT IS VITAMIN D?
- 2 WHY IS VITAMIN D IMPORTANT?
- 3 DAILY NEED OF VITAMIN D
WHAT IS VITAMIN D?
I start immediately with a clarification: when we talk about vitamin D in human nutrition, we are actually talking mainly about two compounds.
In fact, the main forms of vitamin D are the D2 Vitamin and the D3 Vitamin.
So we have:
- Vitamin D2 which derives from ergosterol, also called “provitamina D2”, of purely vegetable origin.
- Vitamin D3 which instead is a derivative of 7-dehydro-cholesterol, or "provitamin D3", and has animal origin.
Both act in the body with the same efficacy, but the first we take only through the diet, while the second (the D3 vitamin) we are able to biosynthesize it independently.
In fact, D3 is a metabolite of cholesterol, and it is also the only vitamin we can produce on our own.
The amount of D2 vitamin present in vegetables taken with the diet is relatively low compared to that taken with food of animal origin or with respect to endogenous synthesis.
For this reason, from now on we will talk about Vitamin D3 for convenience.
THE SUN AND VITAMIN D
However, the D3 vitamin is not produced actively by our body. As I said, it comes from 7-dehydro-cholesterol, but how does this molecule become vitamin D3?
This cholesterol derivative is in fact transformed into its active form by photochemical action of the ultraviolet rays.
In essence it reacts at the level of the skin with sunlight.
This allows us to obtain the active vitamin D3Called cholecalciferol.
This is why the sun is fundamental: without exposure to the sun the precursors of the D3 vitamin are synthesized equally, but our body is not able to use them.
Just sunbathe to increase the amount of Vitamin D3 within our body. The same is also true for the D2 vitamin, which in active form is also called ergocalciferol.
CHEMISTRY OF VITAMIN D3
At this point our vitamin D is activated, and can enter the chain of last two reactions that separate it from its biological utility.
The cholecalciferol (which we recall being the scientific name of the vitamin D3) present in the blood comes carried in the liver, where it becomes 25-hydroxyvitamin D.
This then comes transported to the kidneys where it is converted to 1,25 dihydroxyvitamin D.
This last compound represents the final form of the D3 vitamin, the one that will act on the cellular structures of our body.
TOO MUCH LITTLE VITAMIN DO IT?
Our body obviously leaves nothing to chance.
The amount of D3 vitamin in our body varies greatly depending on the latitude we live in, the time of year, our lifestyle.
Here's how we adapted to these differences:
For the periods in which we take little sun, such as dwinter, we are able to store a certain amount in the liver.
Contrary to what we commonly think, the bone is not the target tissue of vitamin D, but theintestine.
At intestinal level it induces the synthesis of a protein that will bind calcium: only thanks to this protein, called calbindin, the calcium can be fixed to the bones.
We all know how important calcium is for our skeletal system: in children it is used for bone growth, while in adults it allows the maintenance of a good level of bone mass.
WHY IS VITAMIN D IMPORTANT?
To say that vitamin D is indispensable for bone growth and for the calcium and phosphorus metabolism it would already be enough to make us understand how important it is for our health.
However, vitamin D has others less known functions, which I want to talk about now.
VITAMIN DE CANCER
It has been demonstrated1 that adequate intake of vitamin D, especially in menopausal women, significantly decreases the occurrence of carcinomas.
So the D3 vitamin has aanticancer action, or antitumor but also anti-proliferative, especially as regards the breast and lung cancer2.
VITAMIN DE MULTIPLE SCLEROSIS
A lot of research6 have linked optimal levels of vitamin D with a lower probability of being affected by multiple sclerosis.
It has even come to suggest that low levels of vitamin D could be a biomarker of this disease.
We can really say that taking a sufficient dose of vitamin D is important for the prevention of multiple sclerosis.
VITAMIN DE DEPRESSION
The D3 vitamin also helps us maintain excellent mental and physical health. Take daily doses of vitamin D indeed prevents depressive symptoms.
In particular, postpartum depression decreases7 if taken as a supplement in the last months of pregnancy.
If you think your bad mood may be caused by low vitamin D3, we have already talked about the costs to test it with a sample in our article on symptoms of vitamin D deficiency.
VITAMIN DE IMMUNE RESPONSE
That the D3 vitamin stimulates and activates our immune system is known. Historically, it is tuberculosis therapy.
In more recent times it has been observed that it helps to decrease the incidence of HIV. From this we can understand that vitamin D also has antimicrobial and antiviral function.
The same seasonal ailments5 may be due to the low availability of vitamin D during the winter months.
If you suffer often colds, coughs or flu relapses you might be interested in this deepening.
VITAMIN D TO SHORTEN
Several scientific studies3 led to the conclusion that a D3 vitamin deficiency is to be linked toobesity. Have one Healthy diet with the right amount of vitamin D it helps you lose weight!
VITAMIN D TO LIVE LONGER
Regardless of the cause of death, a comprehensive study4 a few years ago it showed that people with optimal plasma vitamin D levels had a lower mortality rate than low-level individuals.
Right plasma D3 vitamin levels make us live longer.
DAILY NEED OF VITAMIN D
We have already said that vitamin D is a panacea for our psychophysical well-being.
But how much do you have to take on to guarantee all the benefits we talked about above?
The minimum daily dose recommended by the Italian Ministry of Health for adults is 5 micrograms per day, for both men and women.
However, many of the studies we talked about earlier suggest that the greatest beneficial effects occur at higher doses.
In any case a blood level lower than 100 nanograms per milliliter is considered safe.
This level can only be reached with prolonged intake of supplements containing more than 250 micrograms of vitamin D.
HOW MUCH DO YOU NEED TO TAKE?
Now we come to the practical part: how long should we be in the sun to meet these needs?
According to a very recent study by the University of Valencia8, this data is not so obvious to obtain.
I state that this study was conducted on subjects who had not applied sunscreen, which as we know is a very important protection against melanomas.
Obviously, however, his presence slows down the reaction of provitamin D with UV rays. In addition, the subjects had skin type III skin, typical of Mediterranean populations.
If you have lighter skin you could risk getting burned well before reaching the desired vitamin D dose.
So we can already understand that the data obtained are a simple average, which can vary according to age, type of skin, type of clothes worn, position taken during exposure, exposure time.
In the summer, according to this study, they would be needed at least 20 minutes during the central hours of the day, or around noon, to reach the recommended dose.
In winter the necessary hours become 2, which can also rise to 9 if exposure occurs early in the morning. Obviously these times are unrealistic and rarely coincide with everyday life.
In fact, the conclusion of this study is that almost no one can get the vitamin D needed just by sunbathing in the sun.
They are therefore recommended D3 vitamin-rich foods, and where necessary supplements.
RICH FOOD OF VITAMIN D3
The foods richest in vitamin D are of animal origin: the famous Cod liver oil he is rich.
Fatty fish (such as the salmon), the egg yolk, liver and red meats.
... but an excess of food of animal origin has a negative impact at various levels of health, in fact the international bodies for the protection of health advise against excessive use.
The vegetable kingdom does not come to us as well: there are only just enough quantities in the mushrooms.
LACK OF VITAMIN D IN ITALY
With all that we have said so far, it will not be surprising to know that the80% of Italians lack vitamin D, based on data from the Italian Society of Osteoporosis, Mineral Metabolism and Skeletal Diseases (SIOMMMS).
We have already talked about the symptoms of low vitamin D and how to get a dosage of blood levels in another article.
To be able to fill these gaps and maintain one's level of well-being, we recommend a diet rich in fatty fish.
Where this is not possible, as in the case of one Vegetarian diet, the only solution remains supplements.
At this point we are sincere with ourselves and ask ourselves if in the winter we are in the sun for at least 9 hours every day:
...personally, on the coldest days it's already so much if I stay in the sun for 9 minutes! : )
But the benefits of vitamin D are so many that one should not take his intake lightly.
With the arrival of summer it is good to take advantage of the sun to tan, without forgetting sunscreen.
Better to use Vitamin D supplements than risk an ugly erythema, if not worse.
And you, do you think of taking the necessary vitamin D every day?
The symptoms of low D3 vitamin are many, and you can discover them all here .
Do you already use supplements?
Leave me a comment on what you think after reading this article, I will be very pleased to answer you!
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The information provided by the manuelcasadei.com website is not intended to diagnose, treat and prevent any discomfort or disease. The user of this website is always responsible for his health and Manuel Casadei encourages you to follow these advice with the approval and supervision of a trusted doctor and disclaims any responsibility for actions taken following what is written in these pages.
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