Caffeine as an Ingredient in Sugar Sweetened Beverages - Caffeine: Chemistry, Analysis, Function and Effects - page 24

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Figure 2.2

The impact of increasing doses of caffeine on the body. This figure
describes some of the body's responses to taking in caffeine. At lower
doses the effects are stimulatory and a positive impact on performance
and alertness. As the dose increases however, anxiety levels have been
shown to increase and overstimulation occurs and can be seen in

symptoms such as hand shaking.

administered doses as low as 32 mg, however with larger doses of 500 mg
cognitive functioning has been shown to deteriorate (Heckman et al 2010).
Although it has not been well documented, doses of 1000-2000 mg of caffeine
per day have been linked in some cases to anxiety.

2.2.1 Withdrawal from Caffeine
In a critical review of the withdrawal symptoms associated with caffeine,
Juliano and Griffiths (2004) documented the evidence from 57 experimental
studies and 9 retrospective survey studies. Valid withdrawal symptoms
identified were the onset of headaches, a decrease in feeling alert, difficulty
concentrating, fatigue, drowsiness, lower energy levels, a depressed mood, a
decrease in feelings of contentment, irritability, and a decrease in feelings of a
clear head. Withdrawal symptoms most commonly occurred within 12-24
hours following abstinence from caffeine and may last anywhere between two
and nine days. Upon a re-dose of caffeine, withdrawal effects are rapidly