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Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary (2014)

Chapter: 3 Safety Signals and Surveillance

« Previous: 2 Intake and Exposure to Caffeine
Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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3

Safety Signals and Surveillance

In addition to estimating exposure, another important first step to assessing the public health safety of the growing number of new caffeine-containing food and beverage products entering the marketplace is conducting surveillance and identifying incidents that warrant further investigation. The panelists of the Day 1, Session 2, panel, moderated by Steven E. Lipshultz, M.D., Department of Pediatrics, University of Miami, Florida, considered the types of surveillance in place and the safety signals being detected. This chapter summarizes their panel presentations and the discussion that followed. Box 3-1 describes the key points made by each speaker.

CAFFEINE AND ENERGY DRINK EXPOSURE CALL SURVEILLANCE

Presented by Alvin C. Bronstein, M.D., Rocky Mountain Poison Center

The United States, Puerto Rico, and the U.S. Virgin Islands, plus three Pacific jurisdictions, are served by 56 U.S. poison centers, with all the information from callers contemporaneously entered into a computer database and uploaded approximately every 19 minutes to the National Poison Data System (NPDS). Alvin C. Bronstein described the type of data collected during those calls and presented results from a descriptive analysis of caffeine exposure calls from January 2000 through July 2013 and energy drink exposure calls from June 2010 to July 2013.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

BOX 3-1
Key Points Made by Individual Speakers

Alvin Bronstein described the National Poison Data System (NPDS), a near real- time national public health database, which collects call information from all 56 U.S. poison centers. Although centralized, national medical databases are not perfect, but they can nonetheless serve as a valuable resource for early safety signals. NPDS can provide critical insight into early recognition of trends in chemical, pharmaceutical, and commercial products including caffeine and energy drink exposures.

Bronstein presented the methods and results of a descriptive analysis of poison center calls showing an initial increase but recent stabilization in caffeinated energy product calls between 2010 and 2013. Bronstein opined that it is too early to predict future trends in energy product calls. Eighteen percent of the energy product calls resulted in no effect, with agitation, irritability, and tachycardia being the most frequently reported clinical effects.

In addition to serving as a resource for early safety signals, Bronstein emphasized, the U.S. National Poison Control Center database could be used for more systematic and prospective data collection and analysis related to caffeine exposure.

Ashley Roberts described how industry has used the GRAS process to determine the safety of caffeine as a food or beverage ingredient, including as an ingredient in energy drinks. In addition to NHANES data, industry has relied on data from a wealth of animal toxicity and human safety studies. He disparaged case reports publicized by the media that are not supported by the weight of scientific evidence.

Poison Center Calls and Data

Bronstein described the NPDS as a passive system, not an active system. Calls come from both consumers and health care professionals, with most centers using registered nurses or poison specialists to field the calls and others using PharmDs. All are backed by medical and clinical toxicologists or physicians. Poison centers field two types of calls: information calls, which are questions about substances, events, or medical conditions, and exposure calls. Data collected during the calls include information on 131 clinical effects, or “signs and symptoms,” with all data collected since 2000 available online.

According to Bronstein, in addition to the contemporaneous recording of the calls by poison specialists, the poison centers also maintain a robust products database containing brand name and composition information for more than 390,000 products. The information typically comes directly from the companies that produce the products. Included are

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

4,401 caffeine products, 262 energy drinks, and 36 energy products (i.e., typically energy bars). The database can be searched by ingredient (e.g., taurine), as well as by product name.

Since 2000, poison centers have received about 2.5 million exposure calls per year (see Figure 3-1), with peak times consistently being June, July, and August (Bronstein et al., 2012). The change over time for various types of agents has been very consistent, according to Bronstein, with steady increases during the past 12 years in exposure calls related to analgesics, sedatives/hypnotics/antipsychotics, cardiovascular drugs, and antihistamines.

An Analysis of Caffeine-Related and Energy-Product Exposure Calls, 2000–2013

Bronstein described the methods and results from an analysis of single substance, closed, human exposure calls related to either caffeine (from January 1, 2000, through July 22, 2013) or energy products (from June 18, 2010, through July 22, 2013). For the purposes of the analysis, energy drinks and energy products were combined. July 22, 2013, was chosen as the end date because that was the day Bronstein and his colleagues started analyzing the data. The analysis of energy product calls began on June 18, 2010, because energy product generic codes were not added to the generic code vocabulary until mid-2010. (Products are categorized using a controlled hierarchical vocabulary, with seven energy product generic codes.) Bronstein and his colleagues calculated descriptive statistics; examined changes over time via either linear regression or spline fit; and correlated clinical effect frequencies. They used SAS JMP 9.0 for their analysis.

The researchers identified 48,177 caffeine calls between January 1, 2000, and July 22, 2013, and 6,724 energy product calls between June 18, 2010, and July 22, 2013. In these calls, the caller said that either the caller or his or her child or other person had ingested what was identified as either a product containing caffeine or an energy product.

As shown in Figure 3-2, caffeine exposure calls per day, by year, were not typical of the change over time that other products have shown over the past 12 years (i.e., as shown in Figure 3-1). Also shown in Figure 3-2, energy product exposure calls per day, by year, increased initially and then appeared to level off, although Bronstein stressed that it is too early to predict whether the leveling off will persist.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

image

FIGURE 3-1 U.S. poison center calls per day, 2000–2012.
SOURCE: Bronstein et al., 2012.

Data on the total number of poison center calls received related to caffeine exposure were collected from January 1, 2000, through July 22, 2013, and calls related to energy product consumption from June 18, 2010, through July 22, 2013. Data were analyzed as change over time with linear regression, and correlation with clinical effect frequency. As shown in Table 3-1, of the 6,724 energy product calls analyzed, about 40 percent were for energy drinks containing caffeine only (i.e., without any other substance contributing to caffeine production, so no guarana, kola nut, tea, yerba mate, cocoa, and so forth). Initially, there were a small number of calls for energy drinks containing caffeine and ethanol (alcohol), an observation that led Bronstein to note that he and his colleagues have learned over the course of time that poison center calls can be used to show the effects of product withdrawals (i.e., energy drinks containing both alcohol and caffeine were withdrawn from the U.S. market after the FDA sent warning letters in 2010 to the manufacturers of those products).

With respect to reasons for energy product calls, most calls analyzed (55 percent) were unintentional. Unintentional calls are usually exposures in young children who do not demonstrate intent. The next two most common reasons for energy product calls were for intentional misuse (12 percent) and intentional abuse (8 percent).

With respect to age categories, the highest mean exposures per month were for children aged 2 years (26.50 mean exposures/month), children aged 6 to 12 years (17.50 mean exposures/month), and adults

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

image

FIGURE 3-2 Caffeine and energy product exposure calls per day over time.
SOURCE: Alvin Bronstein. Presented to the Planning Committee for a Workshop on Potential Health Hazards Associated with Consumption of Caffeine in Food and Dietary Supplements on August 4, 2013.

aged 20 to 59 years (42.00 mean exposures/month). Among the 2-yearold children, which Bronstein noted is a prime age for unintentional ingestion of substances, a linear regression revealed that the number of

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

ingestions increased over time between June 18, 2010, and July 22, 2013, but with an r2 value of only 0.41 (p < 0.0001).

Medical outcomes associated with energy product calls received are listed in Table 3-2. Bronstein highlighted that 18 percent of the 6,724 energy product calls between June 18, 2010, and July 22, 2013, showed no effect. About 10 percent had a moderate effect, which includes symptoms such as tachycardia. About 20 percent had minor effects—for example, hyperactivity or other effects that generally resolve. There was one death associated with consumption (2011). Among 2-year-old children, 34 percent of exposures had no effect, 12 percent had a minor effect, and only three children experienced what would be considered a moderate effect.

When Bronstein and colleagues compared the rank order of energy drink central nervous system clinical effects versus the rank order of central nervous system effects for all caffeine-related exposures, calls that did not involve energy products, they noticed similar patterns. For example, the most common central nervous system clinical effect, “agitated/irritable,” for both types of calls ranked third among all clinical effects for energy drinks and fifth for other caffeine-related calls. The next

TABLE 3-1 Energy Product Calls by Generic Code, June 18, 2010, Through July 22, 2013


N

%

Energy Product Generic Code


2,664

39.6

Energy drinks: caffeine only (without guarana, kola nut, tea, yerba mate, cocoa, and so forth) (0200606)

1,870

27.8

Energy drinks: caffeine containing (from any source including guarana, kola nut, tea, yerba mate, cocoa, etc.) (0200605)

1,092

16.2

Energy drinks: unknown (0200608)

711

10.6

Energy products: other (0200609)

318

4.73

Energy drinks: ethanol and caffeine containing (from any source including guarana, kola nut, tea, yerba mate, cocoa, etc.) (0200610)

62

0.92

Energy drinks: no caffeine (from any source) (0200607)

7

0.10

Energy drinks: ethanol and caffeine only (without guarana, kola nut, tea, yerba mate, cocoa, etc.) (0200611)


SOURCE: Alvin Bronstein. Presented to the Planning Committee on Potential Health Hazards Associated with Consumption of Caffeine in Food and Dietary Supplements on August 4, 2013.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

TABLE 3-2 Medical Outcomes for 6,724 Energy Product Calls Received Between June 18, 2010, and July 22, 2013


N

%

Medical Outcome


2,548

37.9

Not followed; minimal clinical effects possible (no more than minor effects possible)

1,301

19.3

Minor effecta

1,205

17.9

No effect

668

9.93

Moderate effectb

482

7.17

Unable to follow; judged as potentially toxic exposure

254

3.78

Not followed; judged as nontoxic exposure (clinical effects not expected)

216

3.21

Unrelated effect; exposure was probably not responsible for the effect(s)

29

0.43

Major effectc

20

0.30

Confirmed nonexposure

1

0.01

Death


NOTES: aminor effect = symptoms that generally resolve, for example, hyperactivity; bmoderate effect = possible harm with symptoms such as tachycardia; cmajor effect = serious harm or death.
SOURCE: Alvin Bronstein. Presented to the Planning Committee for a Workshop on Potential Health Hazards Associated with Consumption of Caffeine in Food and Dietary Supplements on August 4, 2013.

most common central nervous system clinical effect for both types of calls, “dizziness/vertigo,” ranked seventh among clinical effects for energy drink calls and eighth for caffeine calls. Next for both types of calls was “tremor,” followed by “headache.” In a similar comparison of the rank order of cardiovascular effects, again there appeared to be a good correlation in rank order between the two types of calls. The most common cardiovascular effect, tachycardia, ranked fourth for both energy drink and caffeine calls. The overall correlation of clinical effect frequencies (i.e., all clinical effects recorded) between energy product and caffeine exposure calls was 0.942 (p <0.0001) (Bronstein et al., 2012). Bronstein remarked that he and his colleagues would like to investigate this trend more thoroughly in an effort to identify which components of energy products are responsible for the clinical effects so similar to those being seen with caffeine exposure calls.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

Conclusions About Energy Drink Exposure Calls

In summary, energy product exposure calls to U.S. poison centers initially increased but appear to have stabilized, although without a full year (2013) of data, it is difficult to know whether the trend has in fact stabilized. Most energy product exposure calls are unintentional, followed by misuse and abuse. The most frequently reported clinical effects were agitation, irritability, and tachycardia. But 18 percent of energy product calls were recorded as having no effect. Bronstein and his colleagues believe that the energy product clinical effect pattern is very similar to that of caffeine ingestions, but more work in that area needs to be done. Similarly, although poison center data allow for analysis of calls by specific active agents, more work in that area needs to be done as well.

Limitations of poison center data include the fact that they represent self-reported exposures, whether from health care professionals or the public, so underreporting is likely. Also, exposures are confirmed with clinical laboratory data but only when clinically indicated. Generally, calls are not confirmed.

On the basis of his and his colleagues’ findings, Bronstein made several recommendations for moving forward. Poison centers can assist with data gathering on energy product and caffeine exposure calls by (1) developing a prospective-focused system for data collection in collaboration with the FDA and the IOM; (2) focusing further analyses and surveillance on products with specific active ingredients (e.g., taurine-containing energy products), on vulnerable populations, and on clinical effect profiles of substances (e.g., via cluster analysis); and (3) providing real-time alerts of exposure calls of public health significance.

SAFETY ASSESSMENT OF CAFFEINE IN FOODS AND BEVERAGES

Presented by Ashley Roberts, Ph.D., Intertek Cantox

The industry approach to supporting the safety of food and beverage ingredients, such as caffeine, which includes energy drinks, relies on the GRAS determination process. Ashley Roberts provided an overview of

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

the GRAS process as it pertains to caffeine and briefly considered some current international regulatory positions on the safety of energy drinks.

The GRAS Determination Process

The procedure of establishing the use of a substance as GRAS is FDA regulated. The GRAS status of a food ingredient is based on the consensus of experts qualified by scientific training and experience to evaluate its safety. GRAS status determination requires the same quality and quantity of scientific evidence needed to obtain food additive approval from the FDA, with the major difference being that the safety data used to determine GRAS status must be generally available to the scientific community. Equally important, Roberts said, the mere showing of safety is not sufficient. Rather, the use of the ingredient must be generally recognized as safe, which is normally achieved through publication of research in peer-reviewed journals.

Estimating Human Exposure

A key component in the safety evaluation process is estimating human exposure. According to Roberts, estimates of caffeine consumption can be calculated using the NHANES database.1 On the basis of the data from the 2007–2008 and 2009–2010 NHANES surveys, 348 mg is the estimated daily intake at the 90th percentile for caffeine from background diet (i.e., caffeine in coffee) plus caffeine from energy drinks (i.e., at an incorporation level of up to 120 mg/8 ounces) and dietary supplements for the entire population. The highest estimated daily intake for caffeine from background diet plus energy drinks and dietary supplements at the 90th percentile is for male adults: 444 mg caffeine/day. Roberts observed that, compared to estimates for background exposures, adding energy drinks and dietary supplements to the diet results in a minimal increase in caffeine intake. Roberts noted that the 90th percentile is an FDA benchmark for high consumers and that, other than for male adults, estimates of caffeine intake at the 90th percentile among all other

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1See Chapter 2 for a discussion of how the NHANES database has been used to estimate caffeine exposure among different age groups and changes in caffeine exposure over time.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

groups are below the 400 mg safety threshold level indicated by the FDA to be a safe level.

Roberts identified several limitations of the NHANES database. First, the intake methodology generally overestimates exposure by assuming that all energy drink products in the marketplace have caffeine incorporated at the maximum use level. Exposures are further overestimated by assuming that consumption on a given day is always associated with consumption of caffeine from other sources, including dietary supplements, which may not be the case in real-life situations. Also, the NHANES food survey is a short-term survey over 2 days, which overestimates consumption over the longer term. Despite these limitations, exposure results from NHANES data are similar to those obtained from postmarketing surveillance data, including data from surveys conducted by the FDA and on behalf of the International Life Science Institute (RSEQ, 2011; FDA, 2012; ISQ, 2012; Mitchell et al., 2013). Moreover, two of those other surveys (RSEQ, 2011; ISQ, 2012), both conducted in Canada, collected data on up to 70,000 teenagers, showing that energy drink consumption 4 times or more weekly was found in about 2 percent of subjects, consistent with what the NHANES survey found.

Safety Data

The GRAS determining process for the safe use of caffeine as an added ingredient of food and beverages takes into account a range of data and information from metabolic, pharmacokinetic, animal, and human studies, including data on carcinogenicity, cardiovascular effects, seizures, and other specific effects and data on children and adolescents. Roberts highlighted studies that he thought most relevant.

With respect to the metabolism and pharmacokinetics of caffeine, Kempf et al. (2010) reported that high daily intakes of caffeine from coffee, up to 1 gm/day, do not result in bioaccumulation. Arnaud (2011) reported that caffeine kinetics appears to follow a first-order process, and Hodgson et al. (2013) demonstrated that the kinetics of naturally occurring caffeine in coffee is similar to those of anhydrous caffeine. Roberts remarked that the latter finding was especially interesting because anhydrous caffeine is what is added to products such as energy drinks.

Roberts noted that because the major metabolites produced in humans are almost identical to those found in rodents, this finding supports the use of rodents as animal models for assessing human safety. A com-

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

plete range of toxicity studies has been conducted with animal models, with a no-observed-adverse-effect level (NOAEL) of approximately 100 mg per kg per day for carcinogenicity and reproductive effects (Brent et al., 2011). According to Roberts, that dose is considerably higher than what humans are exposed to on a daily basis and equates to somewhere in the region of 40 to 80 cups of coffee per day.

Human studies suggest that toxic doses of caffeine range from 3 g in young children to 10 g in adults (Iserson, 1990; Nawrot et al., 2003), which is equivalent to the consumption of between 28 and 93 8-ounce servings of energy drinks per day. With respect to specific effects, according to Roberts, caffeine has not been consistently linked with any adverse reproductive consequences. Nevertheless, both the European Commission’s Scientific Committee on Food and Health Canada recommend that the consumption of caffeine during pregnancy be no more than 300 mg per day. To support these recommendations, energy drink companies have labeled their products as not being recommended for pregnant and nursing mothers.

With respect to carcinogenic potential, the International Agency for Research on Cancer has concluded that there is inadequate evidence to confirm that caffeine, as present in coffee, is carcinogenic, a viewpoint that has been confirmed in several large prospective trials (Nawrot et al., 2003; Nkondjock, 2009; Freedman et al., 2012). Roberts noted that, interestingly, the largest prospective study to date (Freedman et al., 2012), with roughly 620,000 subjects, included about 10,000 men and 5,000 women who consumed at least 6 cups of coffee per day, which Roberts opined could result in consumption levels far greater than 1 g caffeine per day.

Human studies on cardiovascular effects have shown that, while caffeine produces a slight but transient increase in blood pressure, other electrocardiogram parameters are not affected. Several reports, including recent meta-analyses of prospective studies, have concluded that the effects of caffeine on cardiovascular function are not clinically significant (IOM, 2001; Pelchovitz and Goldberger, 2011; Bohn et al., 2012; Freedman et al., 2012; Mostofsky et al., 2012). Similarly, for cardiac arrhythmias, results have shown that normal daily caffeine consumption, even when administered as a bolus dose in persons with arrhythmias, was well tolerated (Myers and Reeves, 1991; Pelchovitz and Goldberger, 2011; Menzes et al., 2013). Nevertheless, conflicting results have been reported among excessive consumers of coffee (i.e., more than nine cups per day) (Frost and Vestergaard, 2005; Gronroos and Alonso, 2010).

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

Although a number of case reports regarding seizures may be linked to energy drink consumption (e.g., Iyadurai and Chung, 2007; Trabulo et al., 2011), Roberts opined that these case reports have significant limitations that preclude establishing causality. A large and robust prospective study using data from the Nurses’ Health Study cohort did not identify caffeine as a risk factor for developing seizure (Dworetsky et al., 2010).

Human studies have shown that acute caffeine administration negatively impacts calcium balance and glucose tolerance. Studies also show, however, that the effects on calcium balance can be mitigated through consumption of calcium in the diet (van Dam et al., 2004; Roberts and Rogerson, 2008; Bhupathiraju et al., 2013). Similarly, evidence from prospective studies suggests that caffeine from coffee protects against the risk of type 2 diabetes, thereby mitigating the short-term effects on glucose tolerance (Huxley et al., 2009; Wedick et al., 2011; Freedman et al., 2012; Bhupathiraju et al., 2013).

Available evidence from studies in children (12 years and younger) and adolescents suggests that caffeine results in similar pharmacokinetic and pharmacodynamic effects in younger individuals as those observed in adults (ANZFA, 2000; Meltzer et al., 2008). According to Roberts, the effects of caffeine are therefore considered to be more a function of body weight rather than age. Health Canada has suggested that caffeine consumption by children be limited to no more than 2.5 mg per kg body weight per day (Nawrot et al., 2003; Rotstein et al., 2013). Roberts remarked that caffeine has a long history of safe use in children for the treatment of apnea or prematurity and attention deficit disorder.

In the case of caffeine use in energy drinks, GRAS determinations have also taken into consideration potential interactions with alcohol. Although some researchers have hypothesized that caffeine may antagonize the effects of alcohol, resulting in greater alcohol consumption, the European Scientific Committee on Food and the UK Committee on Toxicity of Chemicals in Food Consumer Products and the Environment have reported that the totality of evidence is currently insufficient to conclude that co-consumption of energy drinks with alcohol is unsafe (SCF, 2003; COT, 2012).

In Roberts’s opinion, the increasing concerns being expressed regarding the use of caffeine in energy drinks come from a number of case reports. All published case reports, however, including incidences of

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

adverse events reported in the FDA’s Adverse Event Reporting System2 database, have been reviewed as part of the GRAS determination process. The expert panels reviewing this information agreed with the FDA’s position that an adverse effect report itself reflects only information as reported and does not represent any conclusion regarding a causal relationship with the product or ingredient. Roberts pointed out that, in addition, the Drug Abuse Warning Network (DAWN) report called into question the causal link between energy drink consumption and emergency room visits because of a number of limitations in the data (SAMHSA, 2013).

In sum, according to Roberts, on the basis of an overall assessment of the safety information, experts have determined that there is no difference in the systematic handling of naturally occurring caffeine and caffeine added to foods and beverages, such as energy drinks. Nor is the premise that adolescents react differently than adults following caffeine consumption supported by the scientific evidence. Roberts noted that the caffeine content in energy drinks is similar to or below that of a number of marketed coffee products and the incremental use of caffeine in energy drinks combined with other sources of caffeine results in total human caffeine exposures below 400 mg/day in all age groups besides adult males. International regulatory positions, including those of the FDA and Health Canada, indicate that caffeine intake up to 400 mg daily is not associated with adverse effects.

In Roberts’s opinion, the concern about caffeinated energy drinks is based on case reports that have been publicized in the media and are not supported by the weight of published scientific evidence on caffeine. The scientific experts who reviewed this evidence thought that the case reports were of limited relevance to a GRAS determination process and that the weight of scientific evidence, in combination with exposure data, supports the safety of caffeine in food and beverage products such as energy drinks.

PANELIST DISCUSSION WITH THE AUDIENCE

Following Roberts’s presentation, the moderator invited the workshop audience to ask questions of either panelist. Most of the discussion

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2The FDA’s Adverse Event Reporting System is a computerized information database designed to provide support for postmarketing safety surveillance for all approved drug and therapeutic biologic products.

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

revolved around the interpretation of poison center data and the potential for future analyses of those data; the idea of a national registry to track health outcomes related to caffeine-containing energy drink exposure; the lack of data on interactions between caffeine and other ingredients in energy drinks (which is the subject of Chapter 6); and limitations of the available data.

Questions About Poison Center Data

There was some confusion about the reasons for poison center calls being categorized as intentional (misuse or abuse) versus unintentional. For example, how is intentional misuse different from unintentional use? Bronstein explained that an example of intentional misuse would be somebody consuming two or three doses of a product when the directions indicated that only one dose should be consumed. Intentional abuse would be the use of a drug or nondrug product for pharmacological effect or intoxication.

There were questions about reporting and whether the analysis that Bronstein presented included reports from both consumers and health care professionals. Bronstein said that the analysis did include both. Most health care professional reports are from emergency department physicians. He observed that, in general, calls from emergency departments are increasing for all substances. Although he and his colleagues did not examine emergency department data specifically, he said, it could be done.

Finally, there was some discussion about the 18 percent of no-effect cases that Bronstein described. An audience member described that specific conclusion as “misleading” because it implied that essentially 82 percent of cases had an effect. However, according to the audience member, on closer examination of children aged 12 years and younger, when cases that were not followed are included, in fact about 82 percent of cases in the pediatric population were asymptomatic and only 18 percent showed symptoms, the majority of which were minor. Bronstein explained that the 18 percent figure he reported was just one piece of information, that is, that 18 percent of all cases, including both pediatric and adult cases, were recorded as no effect. The audience member suggested that pulling and displaying data for children only, that is, for the pediatric population, would be helpful.

When asked how helpful it will be in the future to incorporate into

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

the NPDS information on habitual versus nonhabitual use of caffeine, as well as information on actual caffeine levels, Bronstein replied that that type of information could certainly be collected. Currently, exposures are assigned chronicity, acute, acute-on-chronic, chronic, or unknown. Call history is taken in a manner similar to how physicians talk to their patients, with everyone doing it a little differently. In his opinion, the dataset could be standardized further to collect additional data.

Underreporting and the Need for a National Registry

Bronstein’s mention (during his presentation) of underreporting prompted an audience member to observe that, when looking for information on myocardial infarctions, it became evident that not all emergency departments were capturing those data. Thus, a registry was developed and is now very well established within the United States such that anyone who experiences a myocardial infarction is well documented. Bronstein was asked whether a similar nationwide registry to track exposures and health outcomes might be beneficial in terms of “getting closer to the actual real data.” Bronstein replied, “Absolutely.” He remarked that the beginnings of such a registry already exist. Ninety-five percent of callers to poison centers provide phone numbers. If a nationwide registry could be structured, it would not be difficult to call those callers back and provide them with the option of being entered into a national registry. A national registry would be especially helpful for obtaining information on the effects of chronic exposures.

The Interaction Between Caffeine and Other Ingredients in Caffeine-Containing Energy Drinks

Roberts was asked to describe studies on interactions between caffeine and taurine, which the questioner noted seems to be a popular ingredient in energy drinks, or with any of the other chemical and herbal ingredients in energy drinks. Roberts replied that there are no data on the combination toxicology of the various ingredients in energy drinks. Having said that, all of the other ingredients have undergone the GRAS determination processes. With respect to taurine in particular, he noted that taurine occurs naturally in the diet and is a component of meat, poultry, seafood, and dairy products. It is also present in human breast milk and is

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

added to some infant formulas. The level of taurine in energy drinks has been evaluated in the context of that background exposure scenario and is considered safe.

The Importance of Anecdotal Experience

An audience member disagreed with Roberts’s remark during his presentation that case studies are irrelevant and argued that anecdotal experience helps to generate hypotheses.

Use of Animal Models to Study the Effects of Caffeine

Session 4 (Day 1) speaker Sergi Ferré commented on Roberts’s claim that caffeine metabolites in rats versus humans are the same and that rats therefore serve as a good model for studying the safety of caffeine exposure in humans. He noted that paroxetine, a caffeine metabolite with very strong psychostimulant effects, is a much more active metabolite in humans than it is in rats.

Limitations of the Data

An audience member who described himself as a practicing board-certified emergency physician remarked that he has not been seeing serious side effects from caffeine from any source other than with intentional overdose from over-the-counter pills. He suggested that the approximately 6 billion energy drinks being sold every year in the United States, with an average of only about 2,000 calls per year to poison centers, almost none of which report serious side effects, is pretty strong evidence that energy drinks are in fact very safe products.

Bronstein replied, “Let the data speak for themselves.” Whether the level of analysis he and his colleagues conducted for the purposes of this workshop, with the data they had, presents a “total picture” is unclear at this point. Furthermore, he noted that more studies are needed to determine what, if any, clinical effects are related to caffeine-containing energy drink exposures.

Audience members also offered some additional comments about the limitations of all datasets and how different datasets can lead to slightly different conclusions. For example, Session 3 (Day 2) panelist Steven

Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×

Lipshultz pointed out that the DAWN data suggest that the rate of adverse effects, as indicated by emergency room visits following energy drink exposure, is slightly higher than what the poison center data suggest. In response, another audience member commented that, even with the DAWN data, a numerator of approximately 10,000 (i.e., half of the approximately 20,000 emergency visits were for energy drink exposures alone, that is, not in combination with alcohol or another toxic ingestion) over an estimated 130 million emergency room visits per year suggests that the evidence for serious side effects is lacking. Lipshultz opined that, to the contrary, the DAWN data, as well as NHANES, ILSI, and poison center data, all point to the need for a more formal assessment. Each dataset has its limitations, but each also has it strengths. They all deserve further discussion.

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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
×
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Suggested Citation:"3 Safety Signals and Surveillance." Institute of Medicine. 2014. Caffeine in Food and Dietary Supplements: Examining Safety: Workshop Summary. Washington, DC: The National Academies Press. doi: 10.17226/18607.
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Next: 4 Exploring Safe Caffeine Exposure Levels for Vulnerable Populations »
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Caffeine in Food and Dietary Supplements is the summary of a workshop convened by the Institute of Medicine in August 2013 to review the available science on safe levels of caffeine consumption in foods, beverages, and dietary supplements and to identify data gaps. Scientists with expertise in food safety, nutrition, pharmacology, psychology, toxicology, and related disciplines; medical professionals with pediatric and adult patient experience in cardiology, neurology, and psychiatry; public health professionals; food industry representatives; regulatory experts; and consumer advocates discussed the safety of caffeine in food and dietary supplements, including, but not limited to, caffeinated beverage products, and identified data gaps.

Caffeine, a central nervous stimulant, is arguably the most frequently ingested pharmacologically active substance in the world. Occurring naturally in more than 60 plants, including coffee beans, tea leaves, cola nuts and cocoa pods, caffeine has been part of innumerable cultures for centuries. But the caffeine-in-food landscape is changing. There are an array of new caffeine-containing energy products, from waffles to sunflower seeds, jelly beans to syrup, even bottled water, entering the marketplace. Years of scientific research have shown that moderate consumption by healthy adults of products containing naturally-occurring caffeine is not associated with adverse health effects. The changing caffeine landscape raises concerns about safety and whether any of these new products might be targeting populations not normally associated with caffeine consumption, namely children and adolescents, and whether caffeine poses a greater health risk to those populations than it does for healthy adults. This report delineates vulnerable populations who may be at risk from caffeine exposure; describes caffeine exposure and risk of cardiovascular and other health effects on vulnerable populations, including additive effects with other ingredients and effects related to pre-existing conditions; explores safe caffeine exposure levels for general and vulnerable populations; and identifies data gaps on caffeine stimulant effects.

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