Allergic rhinitis (AR) is triggered by environmental allergens such as pollen and mites, and is associated with several symptoms such as itching and nasal congestion, sneezing or tearing and redness of the eyes. RA can affect patients life quality who suffer it, reducing the quality of sleep and cognitive function, causing irritability and fatigue and, consequently a decrease in work performance.

Because the existing pharmacological treatments for RA are not entirely effective, it is of interest to find other means to enhance the effects of these drugs and decrease more effectively the signs and symptoms associated with RA. In this context, RA has been related to an alteration of the intestinal microbiota (MI).However, there is a need to characterize in detail the MI of individuals who suffer RA.

The main objective of the present study is to characterize the MI of individuals with RA, compared with people without RA. In addition, the secondary objective is to study the association between characteristics of the MI of individuals with RA and different immunological markers.

Inclusion Criteria Allergic Rhinitis population:

1. Men and women over 18 years of age.

2. Sign the informed consent.

3. Present, according to the ARIA classification (Allergic Rhinitis ans its impact on

   Asthma), two or more of the following symptoms for more than one hour a day:

   • Aqueous rhinorrhea.
   • Sneezing, especially paroxysmal.
   • Nasal obstruction.
   • Itching or nasal itch.
   • Conjunctivitis (itching, lacrimation or redness).

4. Individuals presenting Persistent or Perennial type of RA, in which signs are present:

   • More than four days a week.
   • And for more than four consecutive weeks.

Exclusion Criteria Allergic Rhinitis population:

1. Purulent Rhinorrhea.
2. Being pregnant.
3. Be in breastfeeding period.
4. Having diabetes (glucose ≥ 126 mg/dL).
5. BMI values > 30 kg/m^2.
6. Present dyslipidemia (LDL cholesterol ≥ 189 mg/dL and/or triglycerides ≥ 350 mg/dL).
7. Systolic Blood Pressure ≥ 160 mmHg and/or Diastolic Blood Pressure ≥ 100 mmHg.
8. Have received treatment with antibiotics 30 days before the start of the study.
9. Have received treatment with corticosteroids 30 days before the start of the study.
10. Individuals who usually intake prebiotics and/or probiotics supplements 30 days before the start of the study.

Inclusion Criteria Control population:

1. Men and women over 18 years of age.
2. Sign the informed consent.
3. Do not present any signs or symptoms of RA.

Exclusion Criteria Control population:

1. Being pregnant.
2. Be in breastfeeding period.
3. Having diabetes (glucose ≥ 126 mg/dL).
4. BMI values > 30 kg/m^2.
5. Present dyslipidemia (LDL cholesterol ≥ 189 mg/dL and/or triglycerides ≥ 350 mg/dL).
6. Systolic Blood Pressure ≥ 160 mmHg and/or Diastolic Blood Pressure ≥ 100 mmHg.
7. Have received treatment with antibiotics 30 days before the start of the study.
8. Have received treatment with corticosteroids 30 days before the start of the study.
9. Individuals who usually intake prebiotics and/or probiotics supplements 30 days before the start of the study.

In the study will be two types of populations. A population with allergic rhinitis and a population without allergic rhinitis and that serves as control group.