Vitamin D, the “sunlight vitamin”

From being an important element in bone growth to regulating the molecular structures that influence our mood, Vitamin D has numerous roles.

Vitamin D is essential for our health and, in the collective imagination, it is linked closely to the seasons, especially the sun. In Italy and throughout the Mediterranean we have the good fortune of enjoying long hot summers and sunny spring days, which makes a correct level of vitamin D synthesis easier for most of us.

Vitamin D is a liposoluble vitamin, that is also known as calciferol. It plays a huge role in the body’s general wellbeing. It is responsible for regulating the metabolism of phosphate and calcium in our organism and it also helps keep our bones healthy. Nevertheless, unlike other vitamins, it can have a toxic effect on the organism, if our intake is too high. But, at the same time, any deficiency can create a series of imbalances.

The limits of skin synthesis

As we said before, sunlight plays a fundamental role in vitamin D synthesis, as most of what our body needs is provided by skin synthesis and exposing the skin to the sun’s ultraviolet rays. For obvious reasons, this means that synthesis occurs more frequently in summer than in winter. But there are limits to this process, which can reduce or even make correct vitamin D synthesis impossible.

Age is one of these limits, as the passing of time significantly reduces the skin’s capacity to carry out this process. And, if protective clothing or sun protection are used (something that is becoming increasingly frequent due to an increased awareness of the dangers of uncontrolled exposure), we could shield our skin almost completely from its capacity to produce vitamin D. Exposure to sunlight through glass also blocks synthesis as all the UVB rays are absorbed by the glass. Another factor that affects the absorption of vitamin D is the latitude on which we live. In latitudes above the 35th parallel, during winter, sun rays may lack UVB, which means exposure to sunlight is useless for synthesis.

For all these reasons, developing vitamin D deficiencies is much more common than one might think, and these can have different magnitudes and cause different types of problem. To remedy this lack, we can follow various strategies.

The many and transversal benefits of vitamin D

In addition to presiding over the health of our skeleton, vitamin D also performs a series of other fundamental functions. It helps reduce the organism’s inflammatory states and it is responsible for modulating fundamental functions, like skin growth, immune system regulation and glucose metabolism.

Different studies have linked vitamin D deficiencies to low cognitive performance and mood disorders. It also helps stimulate the production of endorphins - the neurotransmitters responsible for putting us in a good mood. There are also many connections between depression, seasonal affective disorders, schizophrenia and vitamin D deficiencies. Some studies using sunlight exposure therapy have shown significant improvements in these pathologies following daily exposure to sunlight.

Vitamin D also plays a crucial role in the health of our skin and the growth of our hair. In fact, it is easy to note how many small skin problems lessen or disappear altogether during the summer, thanks to increased exposure to direct sunlight.

How to avoid systemic vitamin D deficiencies?

The good news is that many foods of animal and vegetable origin, can help us complete our daily vitamin D intake, like oily fish, milk and eggs, as well as nuts, mushrooms and beans. And if what we eat is not enough to give us the quantity we need, we can turn to nutraceuticals and complement our diet with specially formulated food supplements so that our body has everything it needs to function properly.

Vitamin D in skincare

In recent years, vitamin D is also often applied in cosmetics, especially in face products and treatments that help improve the health of the skin barrier, which protects us against the external attacks of pollution, micro-organisms and the weather.

As often happens with other molecules, over time the skin loses its natural capacity to synthesize vitamin D, so supplementing it externally can often prove necessary, from both a systemic and a skincare point of view.

Using a skincare that contains vitamin D can be an excellent idea, not only during the winter months, when the chances of exposure to sun rays diminish drastically, but also in the summer, if you want to guarantee a correct vitamin intake without running any of the risks linked to sunlight exposure.


Penckofer, Kouba, Byrn e Estwing Ferrans, “Vitamin D and Depression: Where is all the Sunshine?” in US National Library of Medicine Jun 2010

Preece, Tomlinson, Ribot, Pietrek, Korn, Davies, Ford, Dunniga, O’Riordan, “Studies of vitamine D deficiency in man” in QJM An international journal of medicine

“Vitamin D” in National Institute of Health

Consuelo H Wilkins, Yvette I Sheline, Catherine M Roe, Stanley J Birge, John C Morris, “Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults” in National Library of Medicine Dec 2006

“Deficit di vitamina D in dermatologia” in Società italiana di dermatologia, medica, chirurgica, estetica e delle malattie sessualmente trasmesse, 2015

Aeqium Newsletter

Subscibe to the newsletter and get an instant discount code of €25 to try our Discovery Set.
Access exclusive benefits, previews of new products, tips from our experts. Every message is a small contribution to your beauty.