It is known as the “sunshine vitamin,” because the sun is primarily responsible for its synthesis. Yet, in sunny Greece, we have a deficiency of the vitamin D necessary for bone health!

The importance of vitamin D

Everything starts with calcium, an element important for the good condition of our skeleton, as well as the proper functioning of muscles, the heart, and our immune system. However, since our body cannot synthesize calcium on its own, it is necessary to obtain it from foods so that the body can create “stores” for the skeleton. Its deficiency is associated with osteoporosis. Additionally, recent evidence shows that vitamin D also helps the proper function of the cardiovascular and muscular systems. It is also believed to protect against some forms of cancer, mainly colorectal cancer.

How do we meet our daily needs?

We need 400 units of vitamin D daily. It has been shown that about 90% of the vitamin D we need comes from the sun. How? Ultraviolet radiation breaks down cholesterol present in the skin, and vitamin D is synthesized this way. It has even been calculated that 20 minutes of daily sun exposure (to the arms and face) is enough to get the amount we need. The remaining 10% of the vitamin D we require comes from foods (dairy products, eggs, and fatty fish). Therefore, it is obvious that the most important source of vitamin D is the sun, and diet acts as a supplementary source. But why isn’t diet enough? Because the amounts of vitamin D found in various foods are rather limited. Thus, if we never saw the sun at all, to get the daily dose of vitamin D we need, we would have to eat 20 eggs or 7.5 liters of milk or 2 plates of sardines. And as is obvious, this is quite impossible.

The Mediterranean paradox

Since vitamin D is synthesized with the help of the sun, one would think that we Greeks, living in a sunny country, should have as much vitamin D as we need. Nevertheless, things are not like that, and according to research, Mediterranean populations paradoxically seem to have a deficiency or at least insufficient amounts of vitamin D in their bodies.

Why does this happen?

Let’s look at some possible causes:

• In the Mediterranean, there are people with darker skin than in northern Europe, so the synthesis of vitamin D from the sun in the skin is hindered by melanin.
• Although we have sunshine for many months of the year, most of the time our hands—the part of the body where vitamin D is synthesized—are covered with clothing. In recent years, we avoid the sun completely because we fear skin cancer.
• We use sunscreens with very high protection factors, which prevent the synthesis of vitamin D in the skin.
• Air pollution in large cities where we move daily prevents solar radiation from finally reaching our skin.
• People over 70 years old experience a 30% decrease in the skin’s ability to produce vitamin D.
• In Mediterranean countries, we do not consume much fatty foods containing vitamin D since the main fat in our diet is olive oil, which does not provide vitamin D.

What can we do?

Certainly, the sun can become dangerous, especially if we receive its rays for a long time and without sunscreen. That is why we must wear a hat, use sunscreen, and avoid excessive sun exposure during dangerous hours. On the other hand, however, we should not forget that exposure to solar radiation is very important not only for the synthesis of vitamin D but also for the better functioning of the whole body (when we sit in the sun, our mood improves, various skin conditions improve, etc.).

Thus, we can follow the ancient Greek saying “Παν μέτρον άριστον” (Moderation in all things) and make sure to spend 15-20 minutes daily in the sun with our face and hands exposed. Let us not forget that the darker our skin, the longer the sun needs to “see” us to produce the necessary vitamin D, bypassing the melanin in the skin that inhibits it. This does not have to happen at the beach; we can “get” the sun we need on the balcony or garden of our home, on the street as we walk, etc. As for sunscreen, we can avoid it during those 20 minutes.

When are supplements necessary?

Special vitamin D supplements are mainly necessary for those suffering from osteoporosis or those older than 65 years. There are products on the market that contain calcium and vitamin D, but there is also a special medication for osteoporosis that additionally contains vitamin D. Regarding side effects, we should be aware of the following:

• Regular vitamin D would need to be taken in enormous doses, impossible to be prescribed by a doctor, in order to cause side effects!
• A special form of vitamin D (alfacalcidol), if taken without medical advice and in large doses, in very rare cases can cause increased calcium levels in urine and blood, and if prolonged, can lead to kidney stones. Therefore, specialists recommend specific tests one month after starting the supplement.

The following table shows the vitamin D content of some foods:

Source: Mednutrition.gr