Caffeine and Blood Pressure - Caffeine and Hypertension

Covering caffeine and blood pressure experiment, medication and a critical review of studies on caffeine and hypertension

Caffeine and hypertension association is a relevant consideration when in comes understanding what causes high blood pressure. There is enough ongoing debate which some would understandably call confusion concerning the relationship between dietary caffeine and blood pressure. Dietary caffeine refers to day to day encounters with caffeine in the food we eat and drink such as coffee, tea, caffeinated drinks and some chocolates.

The link between caffeine and blood pressure has to do with increased high blood pressure and not a cause of low blood pressure. Caffeine is a drug most widely consumed by over 90% of Americans over the age of 20 who drink it in coffee and caffeinated drinks such as sodas on a regular basis. Caffeine is the most active component in coffee to the extent that a 150ml cup of coffee contains 60 to 120mg of caffeine.

The following list shows top five food and beverages that we consume on a day to day basis with the highest levels of caffeine;

  • Coffee, brewed, espresso, restaurant prepared - 21202mg Caffeine
  • Coffee from grounds and prepared with distilled water - 7999mg Caffeine
  • Tea brewed and prepared with distilled water - 4000mg Caffeine
  • Carbonated beverage, low calorie, other than cola or pepper, with aspartame e.g pop,soda, soft drink - 3000mg Caffeine
  • Coffee, instant, regular, powder - 2608mg Caffeine

Caffeine content in tea is about 20-40mg per 150ml cup and about 15-24mg per 180ml of a soda serving. Caffeine is thought to be an important contributing factor to population levels of cardiovascular mortality and morbidity. In fact it has been linked to 14% of coronary heart disease and 20% of strokes.

In a caffeine and blood pressure experiment were caffeine was ingested through coffee, higher systolic blood pressure and higher diastolic blood pressure were observed to the levels of 3.6 and 5.6 mm Hg respectively. These changes in blood pressure were carefully monitored using accurate and approved blood pressure equipment such as the Omron blood pressure monitors. The heart rate of the subjects involved in the experiment also was higher overnight after caffeine consumption.

caffeine and blood pressureCaffeine and hypertension association also comes from the fact that caffeine increases arousal (activity) and decreases fatigue as it contains adenosine an inhibitor of synaptic norepinephrine transmission. Put another way, caffeine increases blood pressure by inhibiting vasodilation which is the relaxation of muscles within the blood vessel walls allowing blood to flow freely. This is the same effect of vasodilation sought by hypertension medications such as diuretics.

Caffeine is also used as an adjuvant. A pharmacological or immunological agent that changes the effect of other agents such as drugs and vaccines whilst having a few or limited effects when given by its own. This adds to the debate on caffeine and blood pressure. It raises even more questions as to what effects caffeine really has on blood pressure.

On the other hand the effect of caffeine on blood pressure is more pronounced in hypertensive or hypertensive-prone individuals than in normotensive (having normal blood pressure) people. This effect on blood pressure can be observed 30 minutes after caffeine consumption peaking at about 60 to 120 minutes after ingestion.

Caffeine and blood pressure a critical review

The quest to establish the link between caffeine and blood pressure has contradicting findings even of epidemiological studies. It would appear regular coffee maybe harmful to some but not all hypertension-prone individuals. The effect of caffeine on blood pressure has been shown to be additive or enhanced during mental and physical stress. It is even profound in older people compared to their younger counterparts. Race or gender has not been found to be of any importance to blood pressure responses to caffeine by yet another group of researchers.

The pressor (blood pressure causing agent) effect of caffeine is said to be stronger in individuals who do not normally ingest caffeine compared to habitual frequent users. Due to individual day to day lifestyles and the food and beverages that people consume, there is a certain level of caffeine found in body plasma. Research shows that the degree to which blood pressure responds to caffeine is inversely related to the plasma caffeine concentration. The greatest blood pressure response is found in people with a lower concentration.

What is still inconclusive and under debate depending on which researcher you choose listen to is the long term effect of caffeine or coffee on blood pressure. This is despite the well known and generally accepted pressor effect of caffeine on blood pressure. Some researchers have also shown that a simple change from caffeinated to decaffeinated coffee or wholesome abandonment of coffee may result in a slight fall of 2-5mm Hg in blood pressure. Yet other studies show no meaningful impact of any change or abstinence from coffee consumption.

In the continued quest to understanding the link between caffeine and blood pressure, medical professionals consider that the absence of any meaningful detection of an increase in blood pressure associated with repeated ingestion of caffeine may be as a result of a development of tolerance. The pressor effect of caffeine has been shown to diminish with a few days of the start of regular intake of caffeine. On the other hand the tolerance is also thought to be partial as in some studies caffeine was still able to elevate blood pressure even during habitual consumption.

Even in the face of much divergence and disagreements as to the extent of the link between blood pressure and caffeine, hypertension treatment will still have to be alive to these different research findings. This also necessitates a hypertension diet conscious of the different perspectives on caffeine and blood pressure. Even hypertension guidelines issued by reputable hypertension institutions such as the American Heart Association (AHA) appear to be sensitive to the debate around this issue.

At an individual level, it's a good idea to check your own blood pressure spikes after taking caffeine. It's best to take readings 30minutes after consumption of coffee or any beverage or foodstuff containing caffeine. By the way caffeine is also counted among beverages and foods that cause halitosis.

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