Effects of daily Laurus nobilis tea on inflammatory biomarkers and stress/anxiety levels: a randomized controlled pilot study in healthy North African participants

Abstract To examine the anti-inflammatory and anti-stress/anxiety effects of Laurus nobilis tea (Lnt) in healthy humans. A randomized, double-blind, placebo-controlled trial was conducted with 55 healthy individuals. Participants consumed either Lnt (intervention group, IG; n = 30) or placebo tea (control group, CG; n = 25) once daily for 10 days. Blood samples were collected at two time points: one day before (Day1) and one day (Day11) after the study. Plasma hematological parameters were analyzed, and the neutrophil-to-lymphocyte ratio (NLR) calculated. Stress and anxiety were assessed using the perceived stress scale (PSS) and the Spielberger state-trait anxiety inventory (STAI). The groups were matched for demographic and clinical characteristics. Compared to Day1, the IG showed significant reductions in leucocytes, neutrophils, NLR, PSS, and STAI on Day11. Compared to the CG, the IG had lower leucocytes (p = 0.004), neutrophils (p = 0.001), and NLR (p = 0.014). Significant interactive effects were observed. Additionally, PSS and STAI scores were significantly lower in the IG on Day11 (p = 0.001). Lnt infusion may regulate NLR levels and could serve as an anti-inflammatory agent and potential protector against inflammation-related. Trial registration: Pan African Clinical Trial Registry (PACTR202205585377035; 13/05/2022). The trial was reported in accordance with the CONSORT reporting guidelines.