ABSTRACT
Background:
Unfiltered Turkish coffee (UTC) is a traditional drink with high levels of bioactive compounds, but evidence of the associated specific physiological effects is inconclusive, and few studies have examined coffee in general. This pilot study aimed to investigate the short-term effects of daily UTC consumption on cardiovascular parameters, lipid profile, appetite-regulating hormones (leptin, ghrelin), glucose metabolism, inflammatory markers, and sleep quality in healthy young women.
Methods:
This is a pilot randomized controlled trial that randomly assigned 40 healthy young women (aged 18-25 years) to intervention and control groups at a 1:1 ratio after 3 weeks of caffeine washout. The intervention group consumed three 40 mL cups of traditional-brewed UTC daily for 4 weeks, whereas the controls maintained abstinence from caffeine. The primary outcomes were cardiovascular (blood pressure, heart rate), lipid parameters, and the secondary ones were appetite hormones (leptin, ghrelin), glucose metabolism (markers), inflammatory biomarkers, and sleep quality, which were evaluated at baseline and at week 4.
Results:
UTC consumption produced significant between-group differences (time × group interactions) compared to controls: systolic blood pressure (+3.0 mmHg; p = 0.025), heart rate (+10.6 bpm; p = 0.007), and insomnia severity scores (+4.05 points intervention vs. -1.00 points control; p ≤ 0.001), while significantly decreasing leptin levels (-0.04 ng/mL; p = 0.014). Significant changes in low-density lipoprotein (LDL) cholesterol were found (p = 0.002), although high-density lipoprotein (HDL) changes were no longer found significant on baseline correction (p = 0.385). Body composition parameters (body mass index (BMI), body fat mass, fat-free mass, skeletal muscle mass) remained unchanged throughout the intervention (all p > 0.05). No significant effects were observed for fasting blood glucose, glycated hemoglobin (HbA1c), inflammatory markers (C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α)), or ghrelin (all p > 0.05).
Conclusions:
Four weeks of UTC intake in this pilot trial were associated with variations in several cardiometabolic variables: interventions in systolic blood pressure (SBP) (+3.0 mmHg) and heart rate (HR) (+11.9 bpm) resulted in higher LDL levels, reduced leptin levels, and poor sleep quality, independent of body composition alterations. However, since the p-values are nominal and not multiplied by a correction, hypothesis-generating results require verification through properly powered studies. These exploratory findings should be considered by individuals with prior cardiovascular risk factors or sleep disorders when considering the intake of unfiltered coffee.
