Vitamin D and the biological cycle of the epidermis

You leave for work in the dark. You come back in the dark. Between one and the other — a window, artificial light and a cup of coffee.

And then you stand in front of the mirror in the morning and see a face that looks more tired than you actually are. A gray complexion, as if dusty. Skin that is less springy. Pores suddenly more visible. And on top of that inflammatory lesions you have not had in years.

This is not solely a matter of mood and the autumn blues. One of the possible causes of such a state of the skin is a vitamin D deficiency.

The sun: the skin's enemy and at the same time its supplier

From a dermatological point of view, sunlight is hard to call a friend of the skin. It is responsible for sun-induced discoloration and erythema. It accelerates skin aging. It stimulates the formation of cancers.

At the same time it triggers a number of necessary processes in the body. One of the more important ones is the cutaneous synthesis of vitamin D — as much as 90% dependent on UV radiation.

And here comes the trouble. Limiting sun exposure is good for the skin, and nobody sensible will tell you to sunbathe in order to improve your vitamin D level. But less sun also means less vitamin D produced by the skin. That shortfall has to be looked for elsewhere.

What vitamin D actually is

It is a group of fat-soluble steroid and organic chemical compounds. It sounds technical, but the range of its action is surprisingly broad.

Vitamin D not only regulates calcium-phosphate metabolism — it also affects:

• the functioning of the immune system,
• maintaining a normal blood glucose concentration,
• protection and regeneration of the skin.

In its active form — calcitriol — it regulates the biological cycle of the epidermis. So it affects not only how the skin looks, but also how it works: how it renews itself and how it heals wounds.

Your skin renews itself every 28 days. Up to a point

The biological cycle of the epidermis is a process in which new cells formed in the basal layer of the epidermis travel towards the surface of the skin — all the way to the stratum corneum. That layer, pushed from below, is destroyed in a way that is completely imperceptible to us.

This process determines the tone and condition of the skin more than most of us suspect. Its frequency and length are key.

• A young person — it takes a cell about 28 days to reach the stratum corneum; the full journey, all the way to shedding, takes about 40 days.
• With age and under the influence of unfavorable external factors — the cycle lengthens, and the 50 days measured in adults is still a value close to normal, not a sign of disease.

What happens when the cycle slows down? Dead cells linger on the surface of the skin. You see the effect in the mirror: a complexion that is increasingly gray and not very firm.

Limited vitamin D synthesis can disturb this process — its active form, calcitriol, governs the maturation of the cells of the epidermis. That is a likely link connecting the autumn gloom outside the window with the gray complexion in the mirror.

One caveat, so as not to promise too much. Vitamin D really is involved in the maturing of the cells of the epidermis — its active form governs the genes responsible for the protective barrier of the skin. That does not mean, however, that supplementation alone will brighten the complexion: such studies in humans simply do not exist. Correcting a deficiency is done for the health of the whole body, and an improvement in the condition of the skin is sometimes an additional effect, not a guaranteed one.

Why the skin cannot cope from October to April

In Poland effective cutaneous vitamin D synthesis takes place from May to the end of September. Between October and April there is practically nothing to count on.

For it to occur, two conditions would have to be met at once:

• being out in the sun for 30 to 45 minutes a day,
• having at least 18 percent of the body surface uncovered — the face, forearms and partly the legs.

Sounds doable? There is a third condition, one that is easy to forget. In this period the sun — not counting cloudy days — effectively "works" only between 10:00 and 15:00. That is, exactly when most of us are sitting at work.

There are also groups whose skin will not produce enough vitamin D even at the height of summer: people over 65, people with a dark complexion, people who work indoors, people who are overweight, and people who use sunscreen all year round — and sunscreen is, after all, something we recommend to everyone. In these situations supplementation is needed all year, not only in autumn and winter.

How much the body needs and where to get it

The daily vitamin D requirement according to the standards adopted in Poland is 1000 – 2000 IU for an adult.

In autumn the body is not able to make up the deficiency on its own — it simply lacks the raw material in the form of sunlight. That is why in this period what gains importance is appropriate supplementation.

A very rich source of vitamin D is oily fish — above all wild salmon, and after it mackerel and trout. Tuna does noticeably worse: it has several times less than wild salmon. There is also cod liver oil, which our mothers used to give us. It contains not only the unsaturated fatty acids that are essential for proper functioning — a single capsule can cover the daily requirement for vitamin D3.

Before you start supplementation, have your vitamin D level measured with a blood test and discuss the result with your doctor. Vitamin D dissolves in fats, so the body stores it. The dose should follow from your actual result, not from a general standard — it is selected by a doctor.

There is also an upper limit, which is talked about less often. For a healthy adult of normal body weight the maximum daily dose taken without medical supervision is 4000 IU. Vitamin D is stored in fat tissue, so with doses taken "just in case" over many months an overdose can occur — it shows up as an excess of calcium in the blood, weakness, nausea and a strain on the kidneys. That is one more reason to set the dose on the basis of a test result and not by feel.

When prevention alone is not enough

Prevention is the most important thing. An appropriate diet and well-considered supplementation are the foundation — both for the skin and for the whole body.

Except that in the rush of everyday duties, consistency tends to be the first thing to disappear. That is when it is worth turning to a specialist and choosing in-clinic care for the autumn period.

An important caveat: a treatment does not replace making up the deficiency. Treat it as support for the natural biological cycle of the epidermal cells — the same one we described above.

One of the solutions most often chosen by patients remains the fractional laser. It exfoliates the accumulated stratum corneum, and that translates into three things:

• improved skin quality,
• a brighter complexion,
• increased permeability of the epidermis — thanks to which active substances from cosmetics are absorbed better.

Whether a treatment makes sense in your case, and which one, is decided by the doctor after examining your skin.

Briefly, in closing

By caring for your body, you also care for your skin and your own wellbeing. It works both ways, and in autumn this is exceptionally clear.

If your skin stays grey and dry despite supplementation, the cause may be something other than the deficiency alone — then it is worth showing it to a doctor at a dermatology consultation, and planning support for regeneration as part of the skin renewal programs.

This article was prepared by the team of the Dr Kuschill MEDESTETIS clinics.

Medical supervision: Joanna Kuschill – Dziurda, MD, PhD, specialist in allergology, specialist in internal medicine, aesthetic medicine physician.