An examination of consumer exposure to caffeine from retail coffee outlets
Introduction
Caffeine is probably the most widely used pharmacologically active substance in the world. Although caffeine is found in a number of foods, it is most frequently consumed in coffee, tea and cola beverages. The ubiquitous nature of coffee and tea consumption highlights the importance of their consumption as a social and cultural element in many societies. However, more commonly caffeine is now being included within non-traditional foods as a “functional” ingredient by many manufacturers.
The influence of caffeine on human health has been studied and discussed extensively (Scientific Committee on Food, 1999, Smith et al., 2000, Committee on Toxicology, 2001, Nawrot et al., 2003), however there is still debate about the potential detrimental effects of caffeine on health.
In Australia and Europe, expert working groups have been recently commissioned to independently investigate and forecast the health impacts of the entry of caffeine containing “energy” drinks into the food system (Scientific Committee on Food, 1999, Smith et al., 2000). Taken collectively, the summarised effects of low caffeine doses (60–200 mg per day – usually spread throughout the day) were enhanced alertness, increased perception of vigour and greater levels of concentration on simple tasks. At these lower doses there appears little concern regarding any significant negative carcinogenic or mutagenic effects in man (Scientific Committee on Food, 1999, Smith et al., 2000).
Higher caffeine doses, however, produce more concerning and less certain effects on health. Detrimental effects such as sleeplessness, anxiety, osteoporosis, hypertension, mental illness, depression, compromised iron and zinc absorption during pregnancy, harm to the unborn child, newborn and nursing infant, cardiovascular disease and anaemia have all been proposed (Smith et al., 2000). In one of the most definitive recommendations against the consumption of larger caffeine doses the Food Standards Agency (FSA) in the UK advised that pregnant women limit their intake of caffeine to no more than 300 mg per day to avoid the “plausible” association between higher caffeine intakes and low birth weight and spontaneous abortion (Committee on Toxicology, 2001). A recent review supporting this recommendation also concluded in establishing no adverse effects levels of caffeine up to 400 mg/day in healthy adults and 45 mg/day for children aged between 4 and 6 years (Nawrot et al., 2003). Similarly, a recent meta-analysis of the effect of coffee and caffeine on blood pressure indicated a dose response effect. Trials containing >410 mg/day of caffeine produced a significantly greater elevation in systolic blood pressure when compare to trials with lower caffeine doses (Noordzij et al., 2005). Despite these reports, the evidence and opinion is clearly divided on the negative health effects of higher caffeine doses.
Surprisingly, little independent data exists on the levels of caffeine found in Australian and New Zealand retail hot beverages (e.g. coffee and teas from cafés and coffee houses) despite the increasing levels of coffee consumption (Australian Bureau of Statistics, 2003). Given the stated uncertainty about the health effects of caffeine and particularly because of its likely dose–response effects, comprehensive values for the distribution of caffeine in coffee (exposure) are pivotal to ensure the accuracy of the ongoing epidemiological evaluation of this relationship. Furthermore, it is necessary that health professionals advising the community about dietary issues (e.g. doctors and dietitians) have accurate information concerning the caffeine content of commonly consumed beverages in order to appropriately provide advice regarding its consumption. Furthermore, public awareness regarding the potential dose of caffeine in retail coffee is arguably a fundamental right of the paying customer, especially for those attempting to modify their caffeine consumption.
It is recognised that commercial beverages with caffeine as a natural component (e.g. tea and coffee) will have a range of potential caffeine doses. These variances are likely the result of many factors which include the species of plant origin, effects of commercial processing and storage along with variances at the retail level such as amount of coffee or tea used, the extraction method (e.g. percolated, drip etc.) and the temperature and amount of water used. However, pilot data collected by Food Standards Australia New Zealand (FSANZ) (unpublished but based on a sample collected in 2002 and using HPLC analysis) suggested that the amount of caffeine supplied in commercial coffees can vary considerably between outlets (espresso coffee ranged 54–167 mg/serve (n = 10)) and that this variance was greater than that previously published (see Table 2).
A recent review of caffeine levels in hot beverages in the United Kingdom also highlighted broad ranges (15–254 mg/serve) of caffeine from retail samples of ground coffee (n = 52) (Food Standards Agency, 2004). The ground coffee samples in this analysis included espressos, long blacks, lattes, filter and cappuccino style coffees. The number of coffee varieties used in this analysis consequently leads to large variances in serve size which may account for some of this range (i.e. vendors using more ground coffee when making larger beverages).
The clarification of caffeine content and the extent of its variance in retail ground coffees will (a) improve the accuracy of estimations of caffeine consumption in Australia and consequently its relationship with ill-health, (b) result in more reliable advice from health care providers on caffeine consumption and (c) enable greater awareness within the population as to the likely exposure of an individual to a certain dose of caffeine. Determining the relationship between caffeine content of espressos and the beverage’s serve size and location of sale will help to identify if these variables are useful predictors of caffeine dose for the consumer. The purpose of this study was to assess the distribution of caffeine content (dose) of standard “espresso” coffees sold by a sample of retail vendors.
Section snippets
Study design
A cross-sectional sample of coffees were collected from five major shopping centres on the Gold Coast, Qld, Australia. Shopping centres were used as a geographical method for cluster sampling.
Sample collection
A single “Take-away Espresso/short black” coffee sample was purchased from all retail vendors housing an espresso machine. Financial implications limited the sample numbers to 100 and sampling ceased at the 5th shopping centre once the sample quota had been satisfied.
The samples were served in the vendors’
Results
Ninety-nine Espresso samples were collected. On examination two samples were found to be in excess of 200 ml and were therefore excluded from the analysis as they were prepared by inexperienced baristas and not considered espresso coffees.
Table 1 provides a descriptive summary of the analysis results. Table 2 displays the present findings compared to previously reported caffeine content data whilst Table 3 demonstrates the potential variance in caffeine exposure if selecting espressos from the
Discussion
The mean caffeine content of retail espresso coffees purchased from Australian vendors in this study (106 mg/serve) is similar to that reported for ground coffees recently collected in the United Kingdom (105 mg/serve) (Food Standards Agency, 2004). These mean figures are higher than those recently quoted in the scientific literature (Barone and Roberts, 1996, Harland, 2000, Mandel, 2002, Knight et al., 2004) of 78, 35, 62 and 85 mg/serve, respectively.
It has been well documented that there is
Acknowledgements
This study was funded by the Heart Foundation Research Centre, Griffith University. The authors thank Linda Jones for her expert assistance with the caffeine analysis.
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