Cardiovascular effects of caffeine - High & Low Blood Pressure Message Board

flowergirl2day · 05-08-2009, 11:57 PM

When reading about the effects of caffeine on the heart and blood pressure, I came across some (referenced) interesting information.

Most of us know that caffeine can acutely raise blood pressure by as much as 10 mmHg. These blood pressure elevations usually happen in individuals who do not use caffeine extensively. In chronic coffee drinkers, the acute effect of caffeine on blood pressure is only minimal or non-existent. (This was news to me).

When combined with stress in the workplace, caffeine contributes to an increase in blood pressure as high as 5-10mmHg in individuals that are not frequently exposed to it. It does not have the same effect on people who consume it in excessive amounts.
The average elimination half-life of caffeine is about five hours (though it can be 3-7 hours for some). For this reason, the plasma concentration of caffeine is the highest in late afternoon. It is at its lowest first thing in the morning, due to the systemic depletion after a night's sleep. This is also why we are so sensitive to that first cup of coffee.

When caffeine causes an acute elevation in blood pressure, it is likely to be higher in older people with hypertension than in people with normal blood pressure. A meta-analysis of 18 clinical trials showed that chronic caffeine use can result in a permanent increase in blood pressure of about 1.2/0.49mmHg. Data from the Nurses's Health study showed that consuming up to six cups of coffee or black tea daily did not increase the risk of hypertension.

What this means to me is that I don't have to feel so guilty about the amount of coffee I drink, which is at least 4 cups a day. This is also consisent with what my hypertension doctor said - "drink it, just don't overdo it".

FG

marantz1935 · 05-09-2009, 12:55 AM

Hello FG,

Hope you are well.

Interesting post!

I love my coffee first thing in the morning (don't we all

). My GP asked me once how much coffee I drank daily. I told him about three cups. He just kinda shrugged his shoulders.

I've noticed on the mornings I don't take a coffee, I feel remarkably calm. It's terrible addiction altogether.

flowergirl2day · 05-09-2009, 11:31 PM

Hi,

I was a bit concerned about my coffee consumption - a minimum of 4 cups of coffee a day. I'd seen seemingly conflicting reports about the effects of caffeine on people. Most tended to be rather negative. So, I got curious and went looking for information from a source I trust.

There is such a thing as caffeine toxicity, but one has to consume an unusually large amount of caffeine to become symptomatic. The amount necessary to produce symptoms varies, depending on body weight and tolerance to caffeine. Because people develop rapid tolerance to caffeine with habitual use, caffeine intoxication is usually seen only in those who consume it infrequently, or in people who have just greatly increased their caffeine intake.

While caffeine interferes with the body's iron absorption and certain prescription and OTC drugs, including those that regulate heart rhythm, like propranolol, it also has legitimate medical uses. In moderate doses it improves alertness and athletic performance, and helps relieve tension headaches. Its addition to pain-relieving drugs increases their effectiveness.

I think some doctors are just as addicted to caffeine as their patients. Ever noticed a Starbucks cup on your doctor's desk?

While living without caffeine would be nice, that first cup (or two) of coffee in the morning works its magic in getting us ready to face the day ahead.

FG

famnd · 05-10-2009, 01:40 PM

There are other chemicals in coffee that can cause problems. i had to give up coffee in my early twenties because of all the palpatations. I tried going back a few times even with decaf which still has some caffeine & probably the other chemicals.

If your b/p isn't affected, then why not? It doesn make one feel good. I recently started drinking one regular coke a day for my sweet tooth. The reason I did that is that my husband has started having so many more sweets around the house which is really tempting me.

I used to drink decaf coke but the taste seems to have changed & it irritates my stomach. Having one sweet a day in the form of a regular coke seems to help keep my sweet tooth under control but I would rather it be decaf. Fam

flowergirl2day · 05-11-2009, 12:13 AM

Quote:

There are other chemicals in coffee that can cause problems. i had to give up coffee in my early twenties because of all the palpatations. I tried going back a few times even with decaf which still has some caffeine & probably the other chemicals.

How true! I experienced nightly palpitations over the last few months, for weeks at a time. My doctor suggested drinking less coffee. I now think they were linked to a medication -a dopamine antagonist-, because they stopped when I discontinued the drug. Because the interactions and possible synergistic effects of caffeine, multiple medications and supplements have likely never been investigated, one can't be too careful.

Coffee does not seem to affect my blood pressure. I am not so sure about its effect on the heart.
High doses of caffeine inhibit calcium reuptake into the smooth muscle cells of the heart and blood vessels, which increases the intracellular calcium. Low doses of caffeine release calcium from from the cells with the same result. Add a calcium channel blocker, which blocks calcium channels in muscle cells of the heart and blood vessels, and a beta blocker...hoping that the electrical conduction and hemodynamics remain well regulated.

Quote:

I recently started drinking one regular coke a day for my sweet tooth

A friend of mine with diabetes does this. She insists on drinking the real thing, rather than a diet version, which would defeat the purpose. I guess it all works out in the end.