Le rôle modérateur de la vitamine D sur les allergies respiratoires (pollens, acariens, chats)

The moderating role of vitamin D on respiratory allergies (pollen, dust mites, cats)

At least 20% of adults are affected by allergies. In addition to conventional treatments, a study has highlighted the importance of vitamin D supplementation!
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Respiratory allergies affect an ever-increasing portion of the population.
At least 20% of adults are affected by significant discomfort, the most common of which is allergic rhinitis.

Among the usual causes of these respiratory allergies, the 3 main ones are: house dust mites, cats and pollens.

There are traditionally three strategies to reduce these allergies, namely:

  • Avoidance (avoiding exposure to the source of the allergy);
  • Medical treatments based on Anti Histamines during periods of crisis;
  • Desensitization with techniques derived from the vaccine model (based on attenuated allergens).

More recently, a fourth way was highlighted by a scientific study carried out on 80 people: Taking vitamin D to reduce the effects of allergy!

Allergic rhinitis: a constantly growing condition

Inserm estimates that the prevalence of allergic rhinitis has quadrupled over the past 30 years.

It currently affects 25% of the adult population (nearly 40% if mild symptoms are included)! These estimates are consistent with those made in neighboring countries.

Adults are the most affected with maximum sensitization which seems to be reached around 40 years of age.
But there is also an increase in allergic reactions from adolescence.

The resulting disorders are equivalent to those of Colds:

  • Sneeze,
  • Runny or stuffy nose,
  • Tingling, frequently associated with eye discomfort (tearing, irritation).

The most severe forms of allergy are a real daily handicap for those affected.

The main causes of respiratory allergies

As mentioned above, respiratory allergies have 3 main vectors:

  • Acarians ;
  • The cats ;
  • Pollen.

Dust mite allergies

Dust mites are tiny spiders, practically invisible to the naked eye and very present in our close environment: at home!

Like all living organisms that cannot regulate their body temperature, the activity of dust mites is directly proportional to the temperature of their environment.

It is nil below 15°C and then gradually increases, and even more in a slightly humid atmosphere.

The atmosphere of a house is therefore perfect for the development of dust mites, which also find there the grounds conducive to their development: fabrics, bedding, carpets.

It is mainly their droppings that are allergenic.

Cat allergies

Contrary to popular belief, it is not cat hair that is allergenic, but a specific protein, FEL d1, present in the saliva and sebum of cats.

We obviously find this protein on the hair, hence the assimilation 'cat hair = allergy'.

This protein triggers in humans an immune reaction (secretion of histamine) more or less intense and at the origin of allergic reactions.

It should also be noted that the synthesis of Protein Fel d1 is highly correlated with the production of sex hormones: Testosterone, Progesterone. As a result, sterilized cats and castrated cats produce much less of it and are therefore less allergenic!

Pollen allergies

Pollen allergy is widespread enough to have its own popular name: hay fever.

The allergens produced by pollens are multiple, different from one species to another and cases of people sensitive to all pollens are relatively infrequent.

Each plant variety has its own pollination period (from birches in early spring to ambrosia in the fall).
Allergic reactions are also seasonal depending on sensitivities to a particular species.

In France, the National Aerobiological Surveillance Network (RNSA) created on the initiative of the Institut Pasteur provides valuable information on the allergenic situation in real time, department by department via their site https://www.pollens.fr/ .

Allergies: what to do to limit the symptoms?

In addition to a specific medical treatment such as taking antihistamines or desensitization, it is possible to put in place several actions to limit the symptoms.

In the context of an allergy to dust mites, the main strategies for limiting exposure to dust mites are:

  • The absence of carpets and rugs: floors allowing complete cleaning easily,
  • Ventilation and exposure to cold and light of bedding items,
  • Dust hunting, largely made up of dust mite droppings,
  • Limit room temperature to 16/17°C.
  • The absence of pets.

If the allergy comes from contact with a cat, the main avoidance strategy is obviously to stay away from cats, and in situations of cohabitation:

  • Limit hair deposits (vacuum the tissues)
  • Brush the cat and clean its footpads frequently, etc.

Finally, if the symptoms appear due to Pollen, it will be necessary to favor the wearing of glasses or even a mask and limit outdoor activities during the periods concerned. You can also rinse your hair frequently.
For example, we advise you not to mow the lawns in times of crisis!

Vitamin D: a new solution to prevent allergies

If specific medical treatments exist, another interesting track is that of Vitamin D.

The positive effects of vitamin D on allergic rhinitis are supported by a scientific study published in 2019.

A group of forty people affected by Allergic Rhinitis received a daily dose of 1000 IU of Vitamin D for 3 months with the measurement of two objective criteria of the intensity of allergic rhinitis:

  • Total Nasal Symptom Score (TNSS)
  • Total eosinophil (white blood cell) count (TEC, Total Eosinophilic Count)

These two measures were compared with the scores of a control group of 40 people not affected by allergies.

Quite logically, the scores of the 'sensitive' group were much higher than those of the control group before the start of the vitamin D treatment.

At the end of the cure, the TNSS and TEC scores of the sensitive group had considerably decreased, to be at levels comparable (and even lower for the TEC) to those of the control group.

The results were convincing enough for the scientific team that conducted the study to write :

This study concludes that vitamin D acts as a disease modulator in allergic rhinitis . In case of allergic rhinitis with vitamin D deficiency, its supplementation brings relief”.