Abstract
Objectives
Turmeric (Curcuma longa) is a popular ingredient in dietary supplements (DS), promoted for a variety of health effects. FDA label regulations require information on the total weight of each botanical or extract present in a botanical DS, unless it is part of a proprietary blend. Information on the concentration of phytochemicals in extracts is voluntary. DS with turmeric rhizome powders and/or extracts were tested for curcuminoid content and the results compared to label claims and industry standards as part of the Dietary Supplement Ingredient Database (DSID) research program. The performance quality of the dosage forms was also evaluated.
Methods
Commonly consumed DS (n = 54 × 2 lots) with turmeric as the only or primary ingredient were analyzed for curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Certified reference materials, in-house controls and blind sample duplicates were measured to ensure the quality of results from three laboratories. Percentages of total curcuminoids (TC) and ratios of the three curcuminoids were compared to published standards. Voluntary content claims were categorized as “complete” (all listed turmeric ingredients had a TC claim) or “partial” (only one of two had a TC claim). Tablets/caplets (n = 9) and capsules (n = 39) were also tested for disintegration and soft gels (n = 4) for rupture.
Results
Measured TC amounts varied widely among products. At the most common labeled level of 500 mg of turmeric per day, measured TC results ranged from 16 to 554 mg (n = 12). DS with voluntary claims for TC (n = 41) had analytical content averaging 6.2% above label, and 63% within ± 10% of claims. DS with complete TC claims had significantly higher levels in mg per day than those with partial or no claims (735 ± 87, 137 ± 37, 196 ± 57; mean ± SE, respectively). The curcuminoid ratios and/or the percentages of TC differed significantly from United States Pharmacopeial (USP) standards for at least 10 DS. Most (87.5%) DS passed disintegration tests and all soft gels passed the rupture test.
Conclusions
Current labeling requirements for turmeric DS may be insufficient to inform researchers and consumers about the actual content of TC in DS because the extract concentrations vary widely. Voluntary claims for TC amounts were reasonably accurate. Most turmeric DS met USP disintegration and composition standards.
Funding Sources
NIH-ODS and USDA-ARS.