dougsmith - 31 October 2007 04:56 PM

SkiCarver - 31 October 2007 04:43 PM

caffeine raises blood pressure as it causes blood vessles to constrict. this causes a greater load on the heart.

Hmm ... do you have a source for that? I’ve never seen any linkage between caffeine intake and increased risk of heart attack or the like.

Indeed, in THIS 2007 article, the authors found:

Habitual intake of caffeinated beverages provided protection against the risk of heart disease mortality among elderly participants in this prospective epidemiologic analysis.

Further, all I can see on the wiki page HERE is an association of caffeine with upset stomach (due to high acidity) and sleep disorder. And I’ve kept my eye out over the past few years as well ...

had a quick look and there seem to ber many opinions on the effects of caffeine WRT to blood vessles, blood pressure and heart rate. Many of the sites I found were less than convincing, on both sides (effect/no effect), but this one at least is a university!

http://www.chm.bris.ac.uk/webprojects2001/crawford/caffeine.html

Ski.

FWIW I think it’s a mistake to try and talk about compounds in isolation as good or bad. The complex interactions of real physiology confound even large-scale epidemiological research, so such assessments are likely to be so full of caveats as to be near meaningless. I wouldn’t recommend methylxanthines like caffeine to a person with hypertension, sleep disorder, anxiety disorder, congestive heart failure, etc. And excessive consumption of anyting with just the right mix of genes and concurrent factors can be harmful. But I wouldn’t run screaming at the sight of a latte or warn people off the stuff either. Few substances are as clearly and unequivocally bad for you as cigarete smoke, yet there have been plenty of people in their 80s and 90s who smoked and got away with it. The moral? COntext is everything, and when you don’t have a good understanding of the context, be cautious.

As I recall, all three of the xanthines, caffeine, theobromine, and theophylline cause vasoconstriction to varying degrees.  Since I’ve always enjoyed caffeine, and after my heart attack my cardiologist prohibited it, I decided to try something.  I got out some nitroglycerine tabs, a caffeine pill and my blood pressure test unit.  I measured my b.p. at ten minute intervals for an hour, took about 60 mg of caffeine citrate, and then kept checking B.P.  About 45 minutes later it started to go up.  When it got about 20 units higher systolic, I put a nitroglycerine tablet (vasodilator) under my tongue.  So, I decided my doctor was probably right and I should avoid caffeine.

Occam

Don’t tell your doctor, though, or youo’ll give him/her a heart attack! Thank God I don’t treat people!

Come on, Brennen.  My logic was impeccable.    How can I assume that the caffeine contributed to this one event when I had been exposing myself to fair amounts of caffeine daily for fifty years, and I had never had a heart attack during that time?  It seemed only reasonable to verify whether caffeine caused significant vasoconstriction, especially since I now had a material (nitroglycerin) that could, and did, reverse it very quickly. 

Although I respect the competence of my cardiologist, about half the doctors I’ve met are klutzes who would be great if their technical skills and judgement matched their egos.  Unless it’s an emergency, I don’t take anything a doctor tells me as gospel without verifying it or at least examining it for reasonability. 

Occam

Well, sadly I have to agree that doctors are not as smart as we’d like them to be. Atul Gawande, one of the smartest, has a great book out called Complications which illustrates effectively why no one is really smart enough to do the job of a doctor these days given the breadth and depth of knowledge needed about medicine and it’s technologies. And that’s even with the hyperspecialization of the human medical world, so imagine what it’s like for us vets! I routinely perform emergency surgery, elective surgery, chemotherapy, ultrasound, endoscopy, and routine well care on at least 5 different species in a single day, so you can imagine how hard it is not to feel hopelessly inadequate sometimes.

But speaking of ego, impeccable logic is only as good as the information it uses. I see lots of people reason impeccably and kill their pets anyway by not knowing some small but crucial fact. Nurses and M.D.‘s are especially good at this since they think they must know far more than I could. Sadly, most of human and dog physiology is the same, but a wee difference in liver enzyme activity has led more than one client of mine to kill their pet with ibuprofen or tylenol. Luckily for you, there wasn’t some similar small but crucial fact missing from your calculations in your little experiment or I might not have the pleasure of teasing you about it.

Occam,your are right sounds reasonable and your logic was impeccable. I must admit that I am not confident about my logic reasonings where my health is in danger, you know, sometimes the sun appears to be revolving around the earth.

Anyway, I admire your commitment to scientific method.