*4.3. Statistical Analysis*

Data are expressed as the mean ± SD. Differences between the groups were compared with the Student's *t*-test (two-tailed). Comparisons before and after treatment with licorice within each group of subjects were obtained with the Student's *t*-test for paired data. The paired *t*-test was also used to compare values before and after DDS-NHOH treatment.

Relationships between pairs of variables were tested by least-squares linear regression. Pearson's correlation coefficient *r* was used to quantify the strength of relationships. The statistical significance of *r* was determined using a *t*-test (two-tailed).

A *p*-value < 0.05 was considered as statistically significant.
