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* Tea may help reduce dementia<ref name="CaffTeaDementSong12"/>, and tea improves learning in rats<ref name="CaffTeaRelaxJune99"/>.
* Theanine and cystine may help reduce the immune system depression of high intensity training<ref name="CaffTheanImune09"/><ref name="CaffTheanImune10"/>.
=Caffeine, Running and Sudden Death=
While rare, the sudden death of a runner does occur and often makes the news. Running is estimated to have a mortality rate of about 1 in 7,000 runners, or one death per 396,000 man-hours<ref name="Thompson-1982"/>. Sudden death during a marathon is rarer, at less than 1 in 50,000<ref name="MaronPoliac1996"/><ref name="RobertsMaron2005"/>.
==Primary Causes of Sudden Death in Athletes==
Sudden death in young competitive athletes (<35 years of age) is mostly due to congenital heart problems, but in older athletes it is usually [http://en.wikipedia.org/wiki/Coronary_artery_disease Coronary artery disease]<ref name="MaronEpstein1986"/><ref name="WallerRoberts1980"/>.
==Myocardial Blood Flow and Heart Attacks==
The heart not only pumps blood but, like any muscle, it requires its own supply of blood as well. If this blood supply, called myocardial blood flow, is interrupted the result is a [http://en.wikipedia.org/wiki/Myocardial_infarction Myocardial infarction] or heart attack. Coronary artery disease, which reduces the myocardial blood flow, is the most common cause of sudden death worldwide.
==Caffeine and Myocardial Blood Flow ==
200mg of caffeine does not change the myocardial blood flow at rest, but during exercise it significantly reduces it<ref name="Namdar-2009"/><ref name="Namdar-2006"/>. This decrease in myocardial blood flow is worse at altitude<ref name="Namdar-2006"/> and in people with Coronary artery disease<ref name="Namdar-2009"/>. This change in myocardial blood flow is not a risk factor for healthy individuals<ref name="Namdar-2009"/><ref name="Namdar-2006"/>, but for those with Coronary artery disease the combination of caffeine and exercise may exacerbate their condition.
==Evaluating the risks==
Because coronary artery disease may not have any initial symptoms<ref name="MayoCAD"/>, risk evaluation is tricky. Some runners who died suddenly had high cholesterol, high blood pressure or chest pains<ref name="WallerRoberts1980"/>. Other risk factors include diabetes, smoking, family history of heart attacks, obesity, long term alcohol use. If you have any risk factors for coronary artery disease, it would be prudent to talk to a healthcare professional.
=Caffeine and health =
For most people, caffeine is generally taken as tea or coffee, to the bulk of the scientific evidence around the health impact of caffeine is based on these beverages.
<ref name="Voermansvan Engelen2011">{{cite journal|last1=Voermans|first1=N.C.|last2=van Engelen|first2=B.G.|title=Coffee and muscle cramps|journal=Neuromuscular Disorders|volume=21|issue=12|year=2011|pages=832|issn=09608966|doi=10.1016/j.nmd.2011.07.006}}</ref>
<ref name="Venables-2008">{{Cite journal | last1 = Venables | first1 = MC. | last2 = Hulston | first2 = CJ. | last3 = Cox | first3 = HR. | last4 = Jeukendrup | first4 = AE. | title = Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. | journal = Am J Clin Nutr | volume = 87 | issue = 3 | pages = 778-84 | month = Mar | year = 2008 | doi = | PMID = 18326618 }}</ref>
<ref name="MayoCAD">Coronary artery disease: Symptoms - MayoClinic.com http://www.mayoclinic.com/health/coronary-artery-disease/DS00064/DSECTION=symptoms </ref>
<ref name="Thompson-1982"> {{Cite journal | last1 = Thompson | first1 = PD. | last2 = Funk | first2 = EJ. | last3 = Carleton | first3 = RA. | last4 = Sturner | first4 = WQ. | title = Incidence of death during jogging in Rhode Island from 1975 through 1980. | journal = JAMA | volume = 247 | issue = 18 | pages = 2535-8 | month = May | year = 1982 | doi = | PMID = 6978411 }}</ref>
<ref name="RobertsMaron2005">{{cite journal|last1=Roberts|first1=William O.|last2=Maron|first2=Barry J.|title=Evidence for Decreasing Occurrence of Sudden Cardiac Death Associated With the Marathon|journal=Journal of the American College of Cardiology|volume=46|issue=7|year=2005|pages=1373–1374|issn=07351097|doi=10.1016/j.jacc.2005.07.008}}</ref>
<ref name="MaronPoliac1996">{{cite journal|last1=Maron|first1=Barry J.|last2=Poliac|first2=Liviu C.|last3=Roberts|first3=William O.|title=Risk for sudden cardiac death associated with marathon running|journal=Journal of the American College of Cardiology|volume=28|issue=2|year=1996|pages=428–431|issn=07351097|doi=10.1016/0735-1097(96)00137-4}}</ref>
<ref name="WallerRoberts1980">{{cite journal|last1=Waller|first1=Bruce F.|last2=Roberts|first2=William C.|title=Sudden death while running in conditioned runners aged 40 years or over|journal=The American Journal of Cardiology|volume=45|issue=6|year=1980|pages=1292–1300|issn=00029149|doi=10.1016/0002-9149(80)90491-9}}</ref>
<ref name="Namdar-2009"> {{Cite journal | last1 = Namdar | first1 = M. | last2 = Schepis | first2 = T. | last3 = Koepfli | first3 = P. | last4 = Gaemperli | first4 = O. | last5 = Siegrist | first5 = PT. | last6 = Grathwohl | first6 = R. | last7 = Valenta | first7 = I. | last8 = Delaloye | first8 = R. | last9 = Klainguti | first9 = M. | title = Caffeine impairs myocardial blood flow response to physical exercise in patients with coronary artery disease as well as in age-matched controls. | journal = PLoS One | volume = 4 | issue = 5 | pages = e5665 | month = | year = 2009 | doi = 10.1371/journal.pone.0005665 | PMID = 19479069 }}</ref>
<ref name="Namdar-2006"> {{Cite journal | last1 = Namdar | first1 = M. | last2 = Koepfli | first2 = P. | last3 = Grathwohl | first3 = R. | last4 = Siegrist | first4 = PT. | last5 = Klainguti | first5 = M. | last6 = Schepis | first6 = T. | last7 = Delaloye | first7 = R. | last8 = Wyss | first8 = CA. | last9 = Fleischmann | first9 = SP. | title = Caffeine decreases exercise-induced myocardial flow reserve. | journal = J Am Coll Cardiol | volume = 47 | issue = 2 | pages = 405-10 | month = Jan | year = 2006 | doi = 10.1016/j.jacc.2005.08.064 | PMID = 16412869 }}</ref>
<ref name="MaronEpstein1986">{{cite journal|last1=Maron|first1=Barry J.|last2=Epstein|first2=Stephen E.|last3=Roberts|first3=William C.|title=Causes of sudden death in competitive athletes|journal=Journal of the American College of Cardiology|volume=7|issue=1|year=1986|pages=204–214|issn=07351097|doi=10.1016/S0735-1097(86)80283-2}}</ref>
</references>
