A study carried out by a group of Brazilian researchers aimed to identify the relationship between salivary uric acid concentrations and the percentage of adolescent fat, which can be used as a biomarker of obesity, for example. This study was motivated by the fact that obesity is a public health problem and that Brazil has more than 50% of the overweight adult population and that about 18.9% of Brazilians are obese.
Therefore, in an attempt to decrease this index, the researchers studied the concentrations of salivary uric acid and its relationship with the person's fat percentage, that is, they used salivary uric acid as a predictor of obesity.
How the study was done
The study was carried out with 248 adolescents between 14 and 17 years old, in the period from 2014 to 2015, and both boys and girls, girls who had already had their first menstruation and adolescents who already had complete dentition were included in the study.
Some exclusion criteria were also defined, such as the presence of caries, absence of teeth, periodontal diseases, chronic diseases, use of medicines for a long period, use of cigarettes, consumption of illicit drugs, use of antibiotics and refusal to collaborate with activities proposed by the researchers. Thus, if the adolescent had any of these criteria, it was not included in the study, since any of these situations could interfere with the concentration of salivary uric acid.
After the study group was established, the researchers started collecting saliva, and the collected samples were sent to the laboratory to evaluate some characteristics such as pH, phosphorus concentration, urea and calcium. In addition, the amount of cholesterol, vitamins D2 and D3 and uric acid was measured, however for these analyzes it was necessary to resort to a second collection, which was indicated to be done at home, this time with the adolescent in 12 hours of fasting.
In addition to the analysis of saliva, a physical examination was also performed, in which height, weight, percentage of fat, bone mass and amount of muscle mass were checked. From the data obtained, the Body Mass Index (BMI) was calculated, and adolescents can be classified into three groups according to the BMI: normal, overweight and obese.
The results obtained were analyzed using a statistical tool in order to verify the relationship between the evaluated parameters.
What was verified
After analyzing the results obtained, the researchers found that there was no relationship between the concentrations of phosphorus, urea, calcium, cholesterol and vitamins D2 and D3 and the percentage of fat. However, they found a relationship between the percentage of fat and the amount of salivary uric acid, with a higher concentration in boys and in those adolescents who had a higher percentage of fat.
Thus, as the results obtained confirmed the study's hypothesis, the researchers were able to propose a predictive model for the percentage of fat based on gender and the amount of salivary uric acid.
This was the first study that found a positive relationship between salivary uric acid and the percentage of fat in a large group. Therefore, further studies are necessary for this correlation to be proven and these parameters can be used in clinical practice.
Why saliva?
Saliva can be obtained non-invasively and painlessly and may contain products of metabolism that may be indicative of changes and, consequently, predictors of disease. Therefore, the evaluation of uric acid could reflect the metabolism of proteins, in addition to being also related to the metabolic syndrome and increased risk of cardiovascular diseases.
The assessment of the concentration of uric acid in salivary as a predictor of a higher percentage of fat and, consequently, of metabolic syndrome is little explored, with only 2 pilot studies having been conducted with a small sample group that identified this correlation. For this reason, saliva is a sample that must be studied so that in the future it can be incorporated into daily clinical practice.
