The caffeine contents of dietary supplements commonly purchased in the US: analysis of 53 products with caffeine-containing ingredients

Abstract

As part of a study initiating the development of an analytically validated Dietary Supplement Ingredient Database (DSID) in the United States (US), a selection of dietary supplement products were analyzed for their caffeine content. Products sold as tablets, caplets, or capsules and listing at least one caffeine-containing ingredient (including botanicals such as guarana, yerba mate, kola nut, and green tea extract) on the label were selected for analysis based on market share information. Two or three lots of each product were purchased and analyzed using high-pressure liquid chromatography (HPLC). Each analytical run included one or two National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) and two products in duplicate. Caffeine intake per serving and per day was calculated using the maximum recommendations on each product label. Laboratory analysis for 53 products showed product means ranging from 1 to 829 mg caffeine/day. For products with a label amount for comparison (n = 28), 89% (n = 25) of the products had analytically based caffeine levels/day of between -16% and +16% of the claimed levels. Lot-to-lot variability (n = 2 or 3) for caffeine in most products (72%) was less than 10%.

Analytical ingredient content and variability of adult multivitamin/mineral products: national estimates for the Dietary Supplement Ingredient Database ,

“…Sample weighing and homogenization procedures were documented previously (29,30). Laboratories were instructed to weigh and then homogenize $20 tablets or capsules before subsampling them for ingredient analyses while following US Pharmacopeia (USP) recommendations for DS sample preparation (31,32) Methods of analysis for vitamins and minerals A previous pilot study identified methods and laboratories for the analysis of vitamins and minerals in MVMs and acceptable intralaboratory relative SDs (calculated as SD/mean 3 100) based on results for NIST SRM 3280 and a commercial MVM (16).…”

A Retrospective Study of Clinical Effects of Powdered Caffeine Exposures Reported to Three US Poison Control Centers

“…In addition, warning labels educating consumers that combining highly concentrated caffeine products with other stimulants, particularly when consumed in conjunction with physical activity, may also help prevent adverse effects such as cardiotoxicity [21,[24][25][26][27][28][39][40][41][42][43][44]. However, given the current lack of regulation of these products, appropriate labeling and product warnings may remain scarce.…”

“…Caffeinated beverages are known to cause severe toxicity when consumed in excess [6][7][8][9][10][11][12][13][14][15][16][17][18]. Dietary supplements that may contain botanical or synthetic caffeine have also produced toxicity in patients, particularly when multiple caffeinated or other stimulant products are used concomitantly, or when products are used in conjunction with physical exertion [19][20][21][22][23][24][25][26][27][28].…”

“…Caffeine has also been used as an ingredient in energy supplement products, commonly ingested beverages, and over-the-counter stimulant medications [21,27,28]. Caffeine is rapidly absorbed with a peak plasma concentration within 60 min and has caused fatal overdoses at estimated doses of 150 mg/kg [29][30][31][32].…”

Involvement of adenosinergic and dopaminergic systems in the regulation of alcohol or sucrose intake: studies in rodent models of self-administration

“…Caffeine is a naturally occurring methylxanthine that acts as a non-selective A1 and A2A adenosine receptor antagonist . This methylxantine is found in common beverages as well as a variety of medications (Barone and Roberts, 1996;Andrews et al, 2007), and is typically consumed in order to increase alertness, arousal and energy (Malinauskas et al, 2007;Smith et al, 2002). Its consumption has been related to changes in performance in normal population (Smith et al, 2002), as well as in people with fatigue (Childs and de Wit, 2008).…”