Neurobehavioral hazard identification and characterization for caffeine

Abstract

This report evaluates the scientific literature on caffeine with respect to potential central nervous system (CNS) effects, specifically effects on sleep, anxiety, and aggression/risk-taking. Caffeine has been the subject of more scientific safety studies than any other food ingredient. It is important, therefore, to evaluate new studies in the context of this large existing body of knowledge. The safety of caffeine can best be described in a narrative form, and is not usefully expressed in terms of a "bright line" numerical value like an "acceptable daily intake" (ADI). Caffeine intake has been associated with a range of reversible physiological effects, in a few studies at levels of less than 100 mg in sensitive individuals. It is also clear that many people can tolerate much greater levels - perhaps up to 600-800 mg/day or more - without experiencing such effects. The reasons for this type of variability in response are described in this report. Based on all the available evidence, there is no reason to believe that experiencing such effects from caffeine intake has any significant or lasting effect on health. The point at which caffeine intake may cause harm to the CNS is not readily identifiable, in part because data on the effects of daily intakes greater than 600 mg is limited. Effects of caffeine on risk-taking and aggressive behavior in young people have received considerable publicity, yet are the most difficult to study because of ethical concerns and limitations in the ability to design appropriate studies. At present, the weight of available evidence does not support these concerns, yet this should not preclude ongoing careful monitoring of the scientific literature.

The clinical toxicology of caffeine: A review and case study

“…Caffeine is known to have generally dose-dependent effects with positive or desirable effects at lower doses (i.e., ≤ 400 mg) and undesirable effects generally above this level of intake, although there is substantial inter-individual variation [ 18 , 19 ]. For example, increased arousal, alertness, concentration and well-being (e.g., increased elation, peacefulness and pleasantness) have been noted at doses of 250 mg in human subjects [ 18 , 20 ], whereas a dose of 500 mg was shown to increase tension, nervousness, anxiety, excitement, irritability, nausea, paresthesia, tremor, perspiration, palpitations, restlessness and possibly dizziness [ 20 ].…”

“…For example, increased arousal, alertness, concentration and well-being (e.g., increased elation, peacefulness and pleasantness) have been noted at doses of 250 mg in human subjects [ 18 , 20 ], whereas a dose of 500 mg was shown to increase tension, nervousness, anxiety, excitement, irritability, nausea, paresthesia, tremor, perspiration, palpitations, restlessness and possibly dizziness [ 20 ]. High, sub-lethal doses (∼7–10 mg/kg) in normal adults may also cause symptoms such as chills, flushing, nausea, headache, palpitations and tremor, although individual responses vary significantly [ [19] , [20] , [21] , [22] , [23] , [24] ].…”

“…As Turnbull et al [ 19 ] have noted in a recent and extensive review of the literature to date, there is no “bright line” or acceptable daily intake which can be derived from such highly variable data as individual tolerance varies so greatly in this regard. Nonetheless, most governmental authorities have determined intake levels which are thought to be safe or lack any significant risk of serious adverse effects in healthy adults.…”

Intake of caffeine from all sources and reasons for use by college students

“…Energy drinks are a relatively new source of caffeine on the market and are popular among young people, especially young males. They are controversial with some scientists expressing concern regarding their safety although others disagree [9,10]. One component of energy drinks that is known to affect behavior is caffeine so their use should be considered in the context of consumption of all caffeine-containing products [11].…”

Chitosan/ Alginate /Gellan Gum Hybrid Hydrogel as a Vehicle for Controlled Release of Drug

“…Hence, this polyelectrolyte complexes has usually been used to control drug release [31][32][33][34]. In this study, caffeine was used as a release drug owing to its cheap, harmless, convenient and productive medicine for pharmacotherapy [35][36][37][38].…”