The UK Food Standards Agency has recommended that pregnant women should limit their caffeine intake, out of prudence, to less than 200mg of caffeine a day– the equivalent of two cups of instant coffee, or one and a half to two cups of fresh coffee. [80] The American Congress of Obstetricians and Gynecologists (ACOG) concluded in 2010 that caffeine consumption is safe up to 200mg per day in pregnant women. [29] For women who breastfeed, are pregnant, or may become pregnant, Health Canada recommends a maximum daily caffeine intake of no more than 300mg, or a little over two 8oz (237mL) cups of coffee. [72] A 2017 systematic review on caffeine toxicology found evidence supporting that caffeine consumption up to 300mg/day for pregnant women is generally not associated with adverse reproductive or developmental effect. [73] Caffeine, like other xanthines, also acts as a phosphodiesterase inhibitor. [173] As a competitive nonselective phosphodiesterase inhibitor, [174] caffeine raises intracellular cyclic AMP, activates protein kinase A, inhibits TNF-alpha [175] [176] and leukotriene [177] synthesis, and reduces inflammation and innate immunity. [177] Caffeine also affects the cholinergic system where it is a moderate inhibitor of the enzyme acetylcholinesterase. [178] [179] Pharmacokinetics Caffeine is metabolized in the liver via a single demethylation, resulting in three primary metabolites, paraxanthine (84%), theobromine (12%), and theophylline (4%), depending on which methyl group is removed. Urinary metabolites of caffeine in humans at 48 hours post-dose [180] In addition, a study linked drinking 2–3 cups of caffeinated coffee (providing about 200–300 mg caffeine) per day to a 45% lower risk of suicide ( 7).

Keep in mind that coffee also contains other substances that improve health. Some benefits listed above may be caused by substances other than caffeine. SummarySome analog substances have been created which mimic caffeine's properties with either function or structure or both. Of the latter group are the xanthines DMPX [210] and 8-chlorotheophylline, which is an ingredient in dramamine. Members of a class of nitrogen substituted xanthines are often proposed as potential alternatives to caffeine. [211] [ unreliable source?] Many other xanthine analogues constituting the adenosine receptor antagonist class have also been elucidated. [212] For most of us, to be caffeinated to one degree or another has simply become baseline human consciousness. Something like 90% of humans ingest caffeine regularly, making it the most widely used psychoactive drug in the world, and the only one we routinely give to children (commonly in the form of fizzy drinks). Few of us even think of it as a drug, much less our daily use of it as an addiction. It’s so pervasive that it’s easy to overlook the fact that to be caffeinated is not baseline consciousness but, in fact, an altered state. It just happens to be a state that virtually all of us share, rendering it invisible. I thought of myself as a pretty good sleeper before I met Walker. At lunch he probed me about my sleep habits. I told him I usually get a solid seven hours, fall asleep easily, dream most nights.

The leaves of Ilex guayusa, the Ecuadorian holly tree, are placed in boiling water to make a guayusa tea. [235]Nehlig A. Effects of coffee/caffeine on brain health and disease: what should I tell my patients? Pract Neurol. 2016;16(2):89-95. doi: 10.1136/practneurol-2015-001162 Consumption of caffeine after abdominal surgery shortens the time to recovery of normal bowel function and shortens length of hospital stay. [48] a b c d e f g h i j k l m n o p "Caffeine". DrugBank. University of Alberta. 16 September 2013. Archived from the original on 4 May 2015 . Retrieved 8 August 2014.