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The information in the archive was published by MAFF, Department of Health and the Scottish Executive before April 1st 2000 when the Food Standards Agency was established.

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Food Surveillance Information Sheet

Number 144      March 1998 ( Number 103 revised)

MAFF UK - SURVEY OF CAFFEINE AND OTHER METHYLXANTHINES IN ENERGY DRINKS AND OTHER CAFFEINE-CONTAINING PRODUCTS (UPDATED)

Index to MAFF UK Food Surveillance Information Sheets, 1998

See also:
21: MAFF UK - Caffeine in Guarana Products (December 1993)
103: MAFF UK - Survey of Caffeine and Other Methylxanthines in Energy Drinks and Other Caffeine-Containing Products (March 1997)

Note

MAFF completed a survey of caffeine and two other methylxanthines (theobromine and theophylline) in a range of "energy" drinks and other soft drinks, teas, coffees and chocolate products in early 1997. The results of this survey were originally published in Food Surveillance Information Sheet number 103 in March 1997. This revised information sheet provides additional results for chocolate bars which have recently been obtained and includes comments from the UK tea and coffee trade (Annex C). It replaces the previous Information Sheet.

Summary

Caffeine levels in standard (non-decaffeinated) cola drinks ranged from 33 to 213 mg/l, while those in low-caffeine colas were not detectable (less than 0.2 mg/l). Energy drinks had a broad range of caffeine contents (0.5-349 mg/l), but most contained more than 110 mg/l. As expected, a wide range of caffeine concentrations was found in the tea and coffee products analysed. Caffeine concentrations in standard tea products ranged from 95 to 430 mg/l, while those in standard instant and ground coffee ranged from 105 to 340 mg/l, when prepared according to a standard method. Variable consumer preparation methods would further broaden the range of caffeine concentrations to which consumers could be exposed. As expected, the two decaffeinated instant coffees analysed contained low levels of caffeine (10 and 11 mg/l) and complied with the relevant statutory limits. Levels of caffeine in chocolate products ranged between 5.5 and 710 mg/kg, with the highest levels being found in chocolate bars. Theobromine levels were low, with the exception of chocolate products, while theophylline was undetectable in most products.

Background

Caffeine (1,3,7-trimethylxanthine) is one of a group of chemicals called methylxanthines which occur naturally in a range of plant-derived foodstuffs such as coffee, tea, cocoa/chocolate and cola products. Caffeine also occurs in soft drinks due to the addition of flavourings containing natural extracts such as cola nut which may contain caffeine and, more frequently, due to the addition of caffeine as such. Although there is no statutory limit for caffeine in soft drinks, its use is subject to the general provisions of the Food Safety Act 1990.1

A number of studies have been carried out to determine the levels of caffeine in coffee, tea, chocolate products and soft drinks.2-16 However, details of the products analysed and the sample weights used in their preparation have often not been reported, thus limiting a comparative evaluation of the data and their usefulness. Moreover, as these studies were generally undertaken over five years ago and most were carried out in the USA, they do not provide an up-to-date picture of the caffeine content of products currently sold in the UK.

In addition to the more traditional caffeine-containing soft drinks such as colas, a new range of drinks, known as "energy" drinks, which are frequently marketed as "revitalising", "stimulating" or providing some sort of "pick-me-up", has entered the market over the last few years. Some of these contain extracts of guarana (Paullinia cupana), a South American plant which has been shown to contain caffeine,16 and many have caffeine added as such. These products typically contain caffeine at higher levels than cola drinks, with concentrations of up to 350 mg/l being reported on the labels of some canned drinks. However, as the majority of these drinks were not available until relatively recently, there is a lack of data on their caffeine content.

MAFF has carried out a survey to provide a reliable quantitative assessment of the caffeine content of a wide range of soft drinks, including energy drinks, and other caffeine-containing products currently available to consumers in the UK. Products have also been analysed for two other methylxanthines, theobromine (3,7-dimethylxanthine) and theophylline (1,3-dimethylxanthine), which are often found along with caffeine and for which data in the scientific literature are generally lacking. The information obtained will expand and update the data generated by MAFF on the composition of food in the UK and may be used to estimate dietary intakes of caffeine. In addition, data obtained on the caffeine levels of energy drinks will not only be used to inform any future EC discussions on these products, but will also assist the European Commission's Scientific Committee for Food (SCF) in its on-going review of these drinks.

Methodology

A total of 162 samples, comprising 36 cola drinks, 26 energy drinks, 12 miscellaneous drinks (mainly soft drinks), 26 tea products (mainly loose, bags and instant), 30 coffees (mainly percolated, filter and instant) and 32 chocolate products (comprising powdered and ready-to-drink milk drinks, chocolate mousses and chocolate bars), were obtained for analysis by MAFF Central Science Laboratory (CSL) Food Science Laboratory, Norwich, between June and December 1996. The majority of these were purchased from retail outlets in and around London, although a small number of energy drinks not available in the UK at the time were obtained direct from the manufacturers. Details of the ingredients listed on the product label and, where appropriate, manufacturers' instructions for preparation, were recorded on receipt.

Tea and coffee infusions were prepared according to a standard method involving 200 ml of boiling water and either: 1.6 g of loose tea (consistent with the use of 1 teaspoonful by Scott et al.9) or instant coffee (consistent with Scott et al.9), 2.6 g of filtered or percolated coffee (equivalent to a level dessertspoonful (10 ml)); or one tea bag. Instant tea was also prepared using 1.6 g of powder, but the results are expressed in terms of the average portion size on the label. Loose and bagged teas were allowed to brew for 5 minutes without stirring, while percolated coffees were prepared by refluxing the coffee under simulated percolator conditions for 10 minutes. Filter coffees were prepared using a domestic coffee filter apparatus. Powdered chocolate drinks were prepared using a reduced sample weight (1 g) in 200 ml of boiling water in order to maintain product solubility on cooling, with the results subsequently being expressed in terms of the portion size recommended on the packet.

All samples were analysed for caffeine, theophylline and theobromine using liquid chromatography with ultraviolet detection (LC-UV), with beta-hydroxyethyltheophylline as an internal standard. Confirmation by liquid chromatography-mass spectrometry (LC-MS) was carried out in cases where peak purity data were outside the quality control limits of 95 per cent purity. Further details of the methods used are given elsewhere.17

Samples were analysed using a batch procedure, with each batch typically comprising 8 test samples, together with 4 quality control samples (an in-house reference material, a duplicate test sample, a spiked sample and a blank) to determine accuracy and precision. In-house reference materials were chosen to matrix-match the respective sample types as closely as possible. In batches of colas, energy and miscellaneous drinks, a cola drink, which had previously been analysed as part of the Food Analysis Performance Assessment Scheme (FAPAS) and which had an assigned value of 104.4 mg/l for caffeine,18 was included. Batches of teas and coffees contained an instant tea material and batches of chocolate products, apart from the chocolate bars, contained a chocolate powder material, with both reference materials having been tested for homogeneity prior to the start of the survey. Spiked samples were fortified at levels similar to those already present in the products.

Between-batch analyses of the in-house reference materials and other control samples showed excellent agreement, being well within the specified acceptance criteria. For example, precision values for replicates of the test samples and in-house reference materials were well within 15 per cent of the mean value and recoveries of the internal standard and spiked samples all met the acceptance criterion of greater than 70 per cent, with most being above 90 per cent. Caffeine concentrations obtained for the cola reference material (mean, 105.9 mg/l; standard deviation, 2.8 mg/l; n=12) were also very close to the FAPAS assigned value of 104.4 mg/l. The survey results were calculated relative to a recovery of 100 per cent for the internal standard, with no other recovery adjustment being made as the recoveries of the methylxanthines relative to the internal standard were close to unity.

Limits of detection of 0.2 mg/l for caffeine and 0.1 mg/l for theobromine and theophylline were obtained for colas, energy drinks, teas, coffees and chocolate infusions, while for chocolate milk drinks, the corresponding detection limits were 1 mg/l and 0.5 mg/l, respectively. Limits of 2 mg/kg for caffeine and 1 mg/kg for theobromine and theophylline were obtained for the chocolate mousse samples. For the chocolate bars, the limits of detection for caffeine, theobromine and theophylline were 50 mg/kg, 20 mg/kg and 30 mg/kg, respectively.

Results

A summary of the concentrations of caffeine, theobromine and theophylline found in the cola, energy and other miscellaneous drinks is given in Table 1, with the results for teas being summarised in Table 2, coffees in Table 3 and chocolate products in Table 4. Individual results for each product are listed in Annex A. Annex B summarises the levels of caffeine in tea and coffee products reported in the scientific literature. Annex C summarises and discusses comments received from the UK tea and coffee trade.

Cola drinks

As shown in Table 1, caffeine concentrations in the 32 samples of standard (diet and regular (non-diet)) cola ranged from 33 to 213 mg/l (mean, 69 mg/l) and are similar to those reported previously by other workers such as Galasko et al.8 (27-146 mg/l), Scott et al.9 (50-90 mg/l) and Sanchez et al.10 (58-147 mg/l). It is interesting to note that in both diet and regular drinks, levels appeared to fall into three distinct sub-ranges, at around 35 mg/l, 75 mg/l and greater than 100 mg/l, perhaps reflecting the different flavouring blends available to manufacturers. In contrast to the standard cola drinks, caffeine was not detected (less than 0.2 mg/l) in the four colas labelled as caffeine-free or decaffeinated or not listing caffeine on the label. Theobromine and theophylline levels were generally below the limit of detection of 0.1 mg/l in both caffeinated and decaffeinated products.

Energy drinks

Caffeine concentrations in the 26 energy drinks analysed ranged from 0.5 to 349 mg/l (mean, 240; median, 293 mg/l) (Table 1), with all but one sample containing over 110 mg/l and most having significantly higher levels than cola drinks. Caffeine concentrations found in individual products (such as Red Bull, Virgin Energy, XTC and X-Plosiv) are similar to those reported previously10,19 and, where given, to those stated on the can label (see Annex A). Caffeine levels in drinks containing guarana extract but with no added caffeine (range, 167-188 mg/l) are also similar to those reported in an earlier survey of these products.16 Lower levels of theobromine (less than 0.1-6.2 mg/l) and theophylline (less than 0.1-1.3 mg/l) compared to caffeine were found in energy drinks.

Miscellaneous drinks

Table 1 also includes data for 12 miscellaneous drinks, comprising two alcoholic drinks and 10 assorted soft drinks. Caffeine concentrations ranged widely (less than 0.2-123 mg/l), with the highest levels being found in the diet and regular varieties of Mountain Dew, a citrus-flavoured drink. Bunker and McWilliams4 reported a similar caffeine concentration (152 mg/l) for this product, while in a later survey by Galasko et al.,8 caffeine was not detected. Detectable concentrations of theophylline (1.2 and 1.4 mg/l) were found only in these two products, while none of the samples contained detectable levels of theobromine (less than 0.1 mg/l).

Tea products

A summary of the levels of caffeine, theobromine and theophylline in the 26 tea products analysed is given in Table 2a. Caffeine concentrations in tea infusions made from 14 standard (non-decaffeinated) bags ranged from 245 to 430 mg/l (mean, 326 mg/l) and are similar to those reported previously4,6,9,11 (Table B1, Annex B). Theobromine levels were lower at 10-31 mg/l (mean, 22 mg/l), also consistent with previous reports.6,9 Theophylline levels in these products were generally low, at up to 2 mg/l. (Comments from UK Tea Trade Technical Committee (UKTTTC) on these results are detailed in Annex C).

The caffeine levels in infusions made from three loose leaf teas ranged from 95 to 105 mg/l (mean 102 mg/l) and are similar to some,4,11 but lower than other8,9 results in the scientific literature (Table B1, Annex B). This difference may reflect the variations in the water:tea ratios used to prepare the infusions, since the amount of caffeine extracted per gram of tea (11.5-12.8 mg (Table 2b)) is within the previously reported range of 5-30 mg (Table B1, Annex B) and agrees closely with two of the three published studies4,11 with which direct comparisons can be made. The caffeine results obtained in the survey are, however, lower than those subsequently reported by the UKTTTC for the same products (Annex C). Theobromine and theophylline levels in the three survey samples were low, at 6-7 mg/l and 0.3-0.5 mg/l, respectively.

After adjusting for portion size (see Table A4), the caffeine concentrations in the three instant tea infusions were in the range, 175-197 mg/l (mean, 183 mg/l), while theobromine levels ranged from 8.1 to 10.3 mg/l (mean, 9.6 mg/l) and theophylline levels were 0.8-1.1 mg/l. Similar levels of caffeine were also reported by Blauch and Tarka,6 although Reid and Good5 found a slightly lower concentration (Annex B).

As expected, caffeine concentrations in infusions made from the two samples of decaffeinated tea bags were very low, at 5 mg/l and 20 mg/l (Table 2a and Annex A). A caffeine content of 125 mg/l was found in the one "low caffeine" product analysed which, in terms of dry tea (8.2 mg/g), is around 40 per cent of that found in normal tea bags (mean, 22 mg/g). Despite this, these tea bags met the manufacturer's claim of containing half the caffeine of its normal bags (17.2 mg/g). The levels of theobromine and theophylline in the decaffeinated and low caffeine products were of the same order as those in the standard bagged teas (15.0-26.5 mg/l and 1.0-1.5 mg/l, respectively).

Coffee products

Levels of caffeine, theobromine and theophylline in the 30 coffee products analysed are summarised in Table 3. As shown, caffeine levels of 210-340 mg/l (mean, 288 mg/l) were found in the 16 standard instant coffees analysed, similar to those reported previously4-6,9,11 (Table B2, Annex B). The two decaffeinated instant coffees analysed contained, as expected, very low levels of caffeine, at 10 and 11 mg/l. As in the case of the teas, levels of theobromine and theophylline in standard and decaffeinated instant coffees were similar.

Caffeine concentrations found in filter and percolated coffee infusions (range, 105-215 mg/l; mean, 180 mg/l) (Table 3) are similar to the levels reported previously by Reid and Good,5 Blauch and Tarka6 and Stavric et al.11 but are significantly lower than those found by Scott et al.9 As with the instant coffees, levels of theophylline and theobromine in the filter and percolated coffees were low. These drinks were prepared using 2.6 g of coffee, equivalent to a dessertspoonful, the portion size per cup recommended on the majority of the product labels as purchased. According to the UK coffee trade, 2.6 g is lower than that used by most consumers who typically use between 3 and 15 g (mean, 7.6 g) per 200 ml cup (see Annex C for further details).

Caffeine levels in the four miscellaneous coffee products ranged from 70 to 580 mg/l (Table 3), with the highest levels being found in an instant espresso product and a coffee and chocolate powdered drink. The concentration of theobromine in the latter sample was also significantly higher than in other coffee infusions, at 60 mg/l, due to the presence of chocolate in the product.

Chocolate products

Levels of caffeine, theobromine and theophylline in the 32 chocolate products analysed (powdered and milk drinks, mousses and chocolate bars) are summarised in Table 4. In the case of the powdered drinks, as noted previously, determinations were carried out using a sample weight of 1 g due to solubility problems on cooling. However, the concentrations reported in Table 4 are expressed in terms of the portion size recommended on the packet. As shown, the concentrations of caffeine in the 18 powdered drinks analysed ranged from 5.5 to 41 mg/l. Previous studies6,9 have found similar results for chocolate drinks and hot cocoa mixes. Higher theobromine concentrations compared to caffeine (range, 85-590 mg/l; mean, 367 mg/l) were found in the powdered drinks which are similar to those previously reported.6 Theophylline levels ranged up to 8 mg/l (mean, 2.9 mg/l; median, 2.5 mg/l).

Table 4 shows that caffeine concentrations in the six chocolate milk drinks ranged from 8 to 20 mg/l, while theobromine levels ranged from 141 to 371 mg/l. The two chocolate mousses had caffeine concentrations of 21 and 50 mg/kg and theobromine contents of 386 and 651 mg/kg. Theophylline was undetectable in the milk drinks and mousses.

Caffeine levels in five of the six chocolate bars ranged from 110 to 340 mg/kg, while the levels of theobromine in these products ranged from 1300 to 4740 mg/kg. Theophylline was not detectable. These concentrations are within the broad range of levels reported in the scientific literature (100-1200 mg/kg and 1300-7000 mg/kg for caffeine and theobromine, respectively).7,12-14 The remaining product was atypical, having a higher cocoa content (70 per cent cocoa beans) than the other chocolate bars and, consequently, higher caffeine and theobromine concentrations (710 and 10370 mg/kg, respectively). The wide range of theobromine levels found in chocolate products is thought to reflect the variable concentrations found in cocoa beans12,20 which are affected by factors such as the origin, degree of maturity at harvest and production techniques.21

Interpretation

As stated earlier, comparison of analytical data on caffeine levels in various foods and beverages reported by different authors is not always straightforward. There are many variables to consider including the sample weight and the volume of water used in preparing some drinks, brewing time (tea) and also different methods of detection, possible changes in drink formulations by manufacturers over the years and use of different formulations to appeal to consumers in different countries. Despite this, the levels of caffeine, theobromine and theophylline found in this survey are generally consistent with previous results.

The Coffee and Coffee Products (Amendment) Regulations 198722 state that the caffeine content of decaffeinated instant coffee products should not exceed 0.3 per cent of dry coffee matter determined using the method of analysis laid down in Commission Directive 79/1066/EEC.23 The two decaffeinated instant coffees analysed were found to comply with these Regulations, having caffeine concentrations equivalent to around 0.1 per cent in the coffee powder. There are no regulations on decaffeinated tea products.

The information obtained in the survey will expand and update the data generated by MAFF on the composition of food in the UK and may be used to estimate dietary intakes of caffeine. In addition, data obtained on caffeine in energy drinks will be used to inform any future EC discussions on these products and will assist the SCF in its on-going review of these drinks.

References
  1. Food Safety Act 1990. HMSO.
  2. Gilbert, R.M., Marshman, J.A., Schweider, M. and Berg, R. (1976). Caffeine content of beverages as consumed. Canadian Medical Association Journal, 114, 205-211.
  3. Groisser, D.S. (1978). A study of caffeine in tea. American Journal of Clinical Nutrition, 31, 1727-1732.
  4. Bunker, M.L. and McWilliams, M. (1979). Caffeine content of common beverages. Journal of American Dietetic Association, 74, 23-81.
  5. Reid, S.J. and Good, T.J. (1982). Use of chromatographic mode sequencing for sample preparation in the analysis of caffeine and theobromine from beverages. Journal of Agricultural Food Chemistry, 30, 775-778.
  6. Blauch, J.L. and Tarka, Jr., S.M. (1983). HPLC determination of caffeine and throbromine in coffee, tea and instant hot cocoa mixes. Journal of Food Science, 48, 745-750.
  7. Terada, H. and Sakabe, Y. (1984). High-performance liquid chromatographic determination of theobromine, theophylline and caffeine in food products. Journal of Chromatography, 291, 453-459.
  8. Galasko, G.T.F., Furman, K.I. and Alberts, E. (1989). The caffeine contents of non-alcoholic beverages. Fd Chem. Toxic., 27, 49-51.
  9. Scott, N.R., Chakraborty, J. and Marks, V. (1989). Caffeine consumption in the United Kingdom: a restrospective survey. Food Science and Nutrition, 42F, 183-191.
  10. Sanchez, S., Bodart, P. and Noirfalise, A. (1996). Taux de caféine dans des boissons non-alcooliseés. Cerevisia, 21(3), 58-61.
  11. Stavric, B., Klassen, R., Watkinson, B., Karpinski, K., Stapley, R. and Fried, P. (1988). Variability in caffeine consumption from coffee and tea: possible significance for epidemiological studies. Fd Chem. Toxic., 26 (2), 111-118.
  12. Zoumas, B.L., Kreiser, W.R. and Martin, R. A. (1980). Theobromine and caffeine content of chocolate products. Journal of Food Science, 45, 314-316.
  13. Kirk, R.S. and Sawyer, R. (1991). Pearson's Composition and Analysis of Foods. 9th Edition. Longman Scientific and Technical, Harlow, Essex.
  14. Love, J.L. Caffeine, theophylline and theobromine in New Zealand foods. Food Technology in New Zealand, January 1989, 29-31.
  15. Bell, L.N., Wetzel, C.R., Grand, A.N. (1996). Caffeine content in coffee as influenced by grinding and brewing techniques. Food Research International, 29 (8), 785-789.
  16. Willetts, P., Buxton, P., Chapman, S., Brereton, P. and Wood, R. (1994). Studies of the properties and xanthine composition of the herbal supplement guarana. Proceedings of Euro Food Tox IV, 443-447.
  17. Ministry of Agriculture, Fisheries and Food (1997). Survey of caffeine in energy drinks and other caffeine-containing products. Report FD 96/39. Final Report submitted by MAFF CSL Food Science Laboratory, Norwich, February 1997.
  18. Ministry of Agriculture, Fisheries and Food (1996). Food Analysis and Performance Assessment Scheme (FAPAS) Report 0313, CSL Food Science Laboratory, January 1996.
  19. Consumers Association (1995). Which?, September 1995.
  20. Hadorn, H. (1980) Theobromine-, caffeine- and total alkaloid contents of cocoa mass. CCB Review for Chocolate, Confectionery and Bakery, 5(3), 26-28.
  21. Timbie, D.J., Sechrist, L. and Keeney, P.G. (1978). Application of high pressure liquid chromatography to the study of variables affecting theobromine and caffeine concentrations in cocoa beans. Journal of Food Science, 43, 560.
  22. The Coffee and Coffee Products (Amendment) Regulations 1987 (S.I. [1987] No. 1986). HMSO.
  23. European Community (1979). Commission Directive 79/1066/EEC laying down Community methods of analysis for testing coffee extracts and chicory extracts. Official Journal of the European Communities L327/17.
Contact Point

For further information please contact:

Dr A M Davies
Joint Food Safety and Standards Group
Additives and Novel Foods Division
Room 232 Ergon House
c/o Nobel House
17 Smith Square
LONDON SW1P 3JR
Tel: +44 (0) 171 238 6217
Fax: +44 (0) 171 238 6263

Spreadsheet Tables

Annex A
Table A1: Concentrations of caffeine, theobromine and theophylline in cola drinks.
Table A2: Concentrations of caffeine, theobromine and theophylline in "energy" drinks.
Table A3: Concentrations of caffeine, theobromine and theophylline in miscellaneous drinks.
Table A4: Concentrations of caffeine, theobromine and theophylline in tea products.
Table A5: Concentrations of caffeine, theobromine and theophylline in coffee products.
Table A6: Concentrations of caffeine, theobromine and theophylline in chocolate products.

Annex B
Table B1: Caffeine concentrations in tea products as reported in the scientifiic literature.
Table B2: Caffeine concentrations in coffee products as reported in the scientifiic literature.

Click here to download the Excel version of Annexes A and B

If you have any other spreadsheet package:
Shift-Click here to download the .csv version of Table A1
Shift-Click here to download the .csv version of Table A2
Shift-Click here to download the .csv version of Table A3
Shift-Click here to download the .csv version of Table A4
Shift-Click here to download the .csv version of Table A5
Shift-Click here to download the .csv version of Table A6
Shift-Click here to download the .csv version of Table B1
Shift-Click here to download the .csv version of Table B2

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