Caffeine, sources

Reported that only coffee among caffeine sources was the significant predictor of hip fracture, although no association between caffeine intake and forearm fracture found. No association between bone density and caffeine intake, although caffeine was found to have significant negative effect on calcium metabolism. 

Overall, coffee is the major source of caffeine, but for many countries tea is the dominant source. In the last 20 years soft drinks have grown to be another significant caffeine source. 

Ground Coffee Food Caffeine source Beverage Coffee plant Food store... 

Pyrimidines and purines occur naturally in substances other than nucleic acids Coffee for example is a familiar source of caffeine Tea contains both caffeine and theobromine... 

Two other commonly found sources of caffeine (16) are kola Cold) from the seeds of, for example. Cola nitida (Vent.) Schott and Engl., which contains 1—4% of the alkaloid, but Httie theophylline or theobromine, and cocoa (from the seeds of Theobroma cacao L.), which generally contains about 3% theobromine and significantiy less caffeine. 

Caffeine. About 3% by weight of the roasted coffee bean is caffeine (16). The second U.S. Department of Agriculture world coffee crop estimate for 1988—1989 was 4.24 x 10 kg (93.3 million 100-lb bags) (102). World coffee consumption was predicted to rise in the foreseeable future at the rate of 1—2% per year and thus the total amount of caffeine and related alkaloids ingested from this source can also be expected to increase. Caffeine and related bases (eg, theophylline) are also found in various teas but, because most of the major producers (India, China, etc) export relatively Htfle of thek crops and keep most for domestic consumption, accurate figures on year-to-year production are more difficult to obtain. Nevertheless, these crops are of significant economic import (103). 

Much research has centered on identifying the source of the purine ring in caffeine. Two possible sources are likely methylated nucleotides in the nucleotide pool and methylated nucleotides in nucleic acids. Extensive experimental work by Suzuki and Takahashi27-30 proposes a scheme whereby caffeine is synthesized from methylated purines in the nucleotide pool via 7-methylxanthosine and theobromine. Information relating to the formation of 7-methylxanthine from nucleotides in the nucleotide pool is sparse. They also provide data that demonstrate that theophylline is synthesized from 1-methyladenylic acid through 1-methylxanthine as postulated by Ogutuga and Northcote.31... 

Foods derived from cocoa beans have been consumed by humans since at least 460 to 480 AD. The source of cocoa beans, the species Theobroma, contains a variety of biologically active components. These include the purine alkaloids theobromine, caffeine, and theophylline. Structurally, they are methylated xanthines and, thus, are often referred to as methylxanthines. Theobromine (3, 7-dimethylxanthine) is the predominant purine alkaloid in cocoa and chocolate. Caffeine (1, 3, 7-trimethylxanthine), the major purine alkaloid found in coffee and tea, is found in cocoa and chocolate at about one eighth the concentration of theobromine. Only trace amounts of theophylline (1, 3-dimethylxanthine) are detected in cocoa and chocolate products. 

Although low levels of methylxanthines have been detected in the leaves and flowers of T. cacao, the primary storage location is within the seed or bean.16 The cocoa bean is the major natural source of the methylxanthine theobromine, but contains only small amounts of caffeine. Theophylline has been detected in cacao beans, but at such low concentrations that its presence generally is ignored. Together, theobromine and caffeine account for up to 99% of the alkaloid content of T. cacao beans. Alkaloid content is affected by genetic makeup, maturity of beans at harvest, and fermentation process. Analytical methodology also is partially responsible for some of the disparity in methylxanthine values since many early methods were unable to separate theobromine and caffeine. 

In 1977, the National Academy of Sciences assessed dietary caffeine intakes by Americans. Based on this data, Graham estimated that 82% of people over 18 years consumed caffeine on a daily basis.54 Dietary caffeine was consumed almost entirely in beverages, with coffee as the major source among adults, and tea and coffee the primary contributor for children aged 1 to 17 years. 

Caffeine intake of children has been investigated in several studies (Table 14). Morgan et al. quantitated the amount and dietary sources of... 

Ref erence/Subj ects Source of Data mg/d Caffeine mg/kg/d... 

Sources of caffeine intake also were assessed in a biradal sample of 1284 children aged 6 months to 17 years during 1973 to 1982 of the Bogalusa Heart Study.56 Overall, mean intakes of caffeine were higher... 

Average Daily Consumption of Caffeine in Children by Food and Beverage Source... 

In the U.K., only 12% of the population reported regular consumption of chocolate beverages. These chocolate beverages provided 1 mg or less of caffeine per day, or less than 0.4% of the daily caffeine intake from all beverage sources.39 Caffeine intake from chocolate foods was not calculated in Scott s study. 

This chapter has compiled and evaluated information on the methylxanthine composition of cocoa and various chocolate foods and beverages, as well as the consumption pattern for these commodities. Cacao is the major natural source of the xanthine base theobromine. Small amounts of caffeine are present in the bean along with trace amounts of theophylline. Numerous factors, including varietal type and fermentation process, influence the methylxanthine content of beans. 

Significant scientific attention has focused on caffeine and its health effects. However, limited data is available for the actual dietary consumption of caffeine or theobromine from individual foods. Even less data exists on the contribution of cocoa and chocolate foods to methylxanthine intake. In children and teenagers, the major dietary source of caffeine was found to be tea, followed by soft drinks and coffee, respectively. Although chocolate foods and beverages ranked the lowest of these dietary sources to provide caffeine, they do constitute the major source of dietary theobromine. In order to gain a better insight into the amount of methylxanthines consumed via the diet, more studies on the methylxanthine content of chocolate foods, as well as beverages, are needed. 

Graham, D., Caffeine - its identity, dietary sources, intake and biological effects, Nutr. Rev., 36, 97, 1978. 

Morgan, K., Stults, V., Zabik, M., Amount and dietary sources of caffeine and saccharin intake by individuals ages 5 to 18 years, Regul. Toxicol. Pharmacol., 2, 296, 1982. 

Mate contains caffeine and, for a group of people in Argentina, Brazil,Paraguay, Uruguay, and Chile, it constitutes the primary source of methylxanthines in the diet.1-2 World production of mate is in excess of 200,0001. Table 1 shows approximate production levels in the several countries where it is grown. 

This chapter will cover the production of coffee, tea, and cocoa, which comprise the primary crops that account for the majority of worldwide caffeine consumption. Caffeine-containing crops and products comprise a large share of the international market and are primary commodities for many national economies.3 4 Trade of such products is also important in the understanding of availability, market demand, and overall exposure to caffeine from various sources. Information is presented to a lesser degree for soft drinks, many of which do contain caffeine and are consumed primarily in the industrialized nations. Another source of caffeine exposure which contributes less than any beverages and foods under consideration are prescription and non-prescription medications, which are described in lesser detail. 

Caffeine consumption is primarily due to coffee, tea and soft drinks. In the U.S., it is estimated that coffee contributes to 75% of the total caffeine intake, tea is 15%, and soda with caffeine accounts for 10% 5 chocolate and other caffeine-containing foods and medications contribute relatively little to overall caffeine exposure. Caffeine also varies by sources tea leaves contain 1.5 to 3.5% caffeine kola nuts contain 2% caffeine and roasted coffee beans contain 0.75 to 1.5% caffeine.6 Coffee varies in caffeine content some analyses have estimated that caffeine may range from 0.8 to 1.8%, depending on the type of coffee.7 Crops of coffee, tea, and cocoa are very similar in their production periods and their useful life in production. Typically coffee, tea, and cocoa trees can be productive with crops every 5 years for a total period of 40 years,8 or an estimated 8 yields per tree. 

Table 1 describes several of the most common sources of caffeine, their region of origin, how they are used and consumed, and the variability in caffeine content.1... 

Source Origin Country producing Consumed form Caffeine content (% total weight)... 

In addition to coffee and tea, the psychological effects of caffeine can be obtained from a number of other food sources. Chocolate is a popular and widely consumed source, but the drug is also found in considerable quantities in a number of medications, both prescription and over-the-counter (OTC). Caffeine tablets (e.g., No-Doz) are sold for those who use the drug to study, drive, or engage in other activities. Less obvious is the caffeine content in analgesics, cold preparations, and anorectants. 

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