Content of Caffeine and Catechins Measured in Multi-ingredient Dietary Supplements Containing Green Tea: Association with Label Claims and Proprietary Blends

Abstract

Abstract Objectives Multi-ingredient dietary supplements (DSs) containing green tea (GT) were analyzed for their phytochemical content (seven catechins and caffeine) as part of a Dietary Supplement Ingredient Database project. The label information required by FDA is the weight of the GT extract or leaf powder, unless it is part of a proprietary blend (only the blend weight needed). Any information about the concentration of GT phytochemicals is voluntary. We assessed the accuracy of the mandatory and voluntary portions of labels and the effect of proprietary blends on the phytochemical content. Methods Two lots of 37 GT DSs, estimated to contain ≥40 mg/serving of GT, were purchased in a variety of market channels. Samples were sent for analysis to two experienced laboratories. Means and standard errors for the analytically measured content of epigallocatechin gallate (EGCG; the most prevalent catechin), the summed content of the catechins (total catechins, TC), and caffeine were derived for each DS and compared to label information. Results The measured content of EGCG, TC, and caffeine showed wide ranges (0 (not detected) - 442, 0–711, and 0–982 mg/day, respectively). DSs with concentration claims for EGCG and caffeine (32% and 43%, respectively) had higher content per serving compared to DSs without such information (P < 0.05). Most DSs with voluntary claims for EGCG, TC or caffeine content (74%) had actual content within ± 20% of the labels. The catechin content was not significantly different in DSs with GT amounts listed on the label (n = 20) compared with DSs listing GT as part of a proprietary blend (n = 17). However, DSs with GT in a blend had significantly more caffeine than those with a label claim for GT amount (means (SE) per day 197 (63) vs. 49 (18), respectively; P = 0.037). Conclusions The actual content of GT constituents such as EGCG, TC and caffeine in multi-ingredient GT DSs varied depending on the labeling formats. DSs with a voluntary label claim for EGCG had significantly higher EGCG content than those with only the required claims. DSs with GT listed as a part of a blend had significantly higher levels of caffeine than products with labeled GT amounts. More complete label information would be beneficial both for consumers and for researchers who track phytochemical intakes and their associations with health outcomes. Funding Sources NIH/ODS and USDA/ARS.