Vitamin D and skin health

Vitamin D is a vitamin with a hormonal function that participates in numerous processes of the organism, among them bone metabolism, the immune system and the functioning of the skin.

The skin cells have receptors for vitamin D, which explains its importance in the regulation of cellular growth, the barrier function of the skin and certain immunological mechanisms.

However, vitamin D is not a solution for all skin diseases nor should it be taken without a medical indication.

Most of vitamin D is produced in the skin after exposure to ultraviolet B (UVB) radiation.

It can also be obtained, in smaller quantity, through some foods and supplements when they are indicated.

The main dietary sources are:

• Oily fish.
• Salmon.
• Sardines.
• Mackerel.
• Tuna.
• Egg yolk.
• Liver.
• Some fortified foods.

Vitamin D participates in:

• The renewal of the epidermis.
• The differentiation of the keratinocytes.
• The barrier function of the skin.
• The regulation of the immune system.
• The production of certain antimicrobial peptides.

These functions help to maintain healthy skin.

Various studies have investigated the relation between vitamin D and diseases such as:

• Psoriasis.
• Atopic dermatitis.
• Vitiligo.
• Alopecias.
• Acne.

Although there are described associations, the scientific evidence does not yet demonstrate that supplementation systematically benefits all patients. Each case must be assessed individually.

A vitamin D deficit can be associated with:

• Alterations of bone metabolism.
• Muscular weakness.
• Greater risk of fractures.
• Alterations of the immune system.

In some patients with certain skin diseases low levels are observed, although this does not necessarily mean that the deficiency is the cause of the disease.

Only when there is a medical indication.

Supplementation is usually considered in people with:

• A deficit confirmed by analysis.
• A greater risk of deficiency.
• Specific clinical situations.

Taking vitamin D without control can provoke adverse effects.

Sun exposure favours the synthesis of vitamin D, but it is not recommended to expose oneself to the sun for a prolonged time or without protection with the objective of increasing its levels.

Ultraviolet radiation accelerates skin ageing and increases the risk of skin cancer.

When there is a deficit, it is usually safer to correct it through diet or supplements prescribed by a professional.

Among them are:

• Older people.
• People with little sun exposure.
• Patients with intestinal diseases that hinder absorption.
• People with obesity.
• People with diets poor in vitamin D.

Some research has observed an association between low levels of vitamin D and certain forms of hair loss.

Nevertheless, the relation is complex and it has not yet been demonstrated that supplementing vitamin D improves alopecia in all patients.

The diagnosis is made by means of a blood test that determines the concentration of 25-hydroxyvitamin D (25-OH vitamin D).

The interpretation of the results must be carried out by a health professional, taking into account the clinical situation of each patient.

It is difficult to cover all the needs exclusively through diet.

Therefore, when there is a confirmed deficiency, the doctor can indicate supplements adapted to each patient.

No.

When there is a skin disease, the correction of a vitamin D deficit can be part of the global treatment, but it does not replace the specific treatments indicated by the doctor specialised in skin health.

• Myth: The more vitamin D I take, the better my skin will be. Fact: It should only be supplemented when there is a medical indication.
• Myth: Sunbathing for hours is the best way to obtain vitamin D. Fact: Excessive sun exposure increases the risk of skin ageing and skin cancer.
• Myth: Vitamin D cures psoriasis. Fact: It can have a role in certain treatments, but it does not cure the disease on its own.
• Myth: All hair loss is due to a lack of vitamin D. Fact: There are multiple causes of alopecia and vitamin D deficit is only one of the possible ones.
• Myth: Supplements are always harmless. Fact: The excess of vitamin D can produce harmful effects and should be avoided.

• Vitamin D participates in numerous functions related to the health of the skin and the immune system.
• A deficit may require treatment, but it must be confirmed by analysis.
• Supplementation should not be carried out indiscriminately.
• It is not recommended to expose oneself to the sun without protection to increase vitamin D levels.
• A healthy diet and individualised treatment are the safest way to correct a deficiency.
• Vitamin D complements, but does not replace, medical skin treatments.