Background: Thermogenic (TRM) supplements are often used by people seeking to decrease body weight. Many TRM supplements are formulated with multiple ingredients purported to increase energy expenditure and maximize fat loss. However, in the past some TRM ingredients have been deemed unsafe and removed from the market. Therefore, it is important to verify the safety of multi-ingredient TRM supplements with chronic consumption.
Objective: To assess the safety of daily consumption of a multi-ingredient TRM supplement over a 28-day period in healthy adults.
Design: Twenty-three recreationally active adults (11M, 12F; 27.1±5.4 years, 171.6±9.6 cm, 76.8±16.1 kg, 26±5 BMI) were randomly assigned either to consume a multi-ingredient TRM supplement (SUP; n=9) or remain unsupplemented (CRL; n=14) for 28 days. Participants maintained their habitual dietary and exercise routines for the duration of the study. Fasting blood samples, resting blood pressure, and heart rate were taken before and after the supplementation period. Samples were analyzed for complete blood counts, comprehensive metabolic, and lipid panels.
Results: Significant (p<0.05) group by time interactions were present for diastolic BP, creatinine, estimated glomerular filtration rate (eGFR), chloride, CO2, globulin, albumin:globulin (A/G), and high-density lipoprotein (HDL). Dependent t-tests conducted on significant variables revealed significant (p<0.05) within-group differences in SUP for diastolic BP (+6.2±5.3 mmHG), creatinine (+0.09±0.05 mg/dL), eGFR (-11.2±5.8 mL/min/1.73), globulin (-0.29±0.24 g/dL), A/G (+0.27±0.23), and HDL (-5.0±5.5 mg/dL), and in CRL for CO2 (-1.9±1.5 mmol/L) between time points. Each variable remained within the accepted physiological range.
Conclusion: Results of the present study support the clinical safety of a multi-ingredient TRM containing caffeine, green tea extract, and cayenne powder. Although there were statistically significant (p<0.05) intragroup differences in SUP from pre- to postsupplementation for diastolic BP, creatinine, eGFR, globulin, A/G, and HDL, all remained within accepted physiological ranges and were not clinically significant. In sum, it appears as though daily supplementation with a multi-ingredient TRM is safe for consumption by healthy adults for a 28-day period.
Keywords: clinical; fat burner; hematology; nutrition; safety; weight loss supplement.