Caffeine affects blood pressure - Term Paper Example

It is categorized as a psychoactive drug, but its consumption is legal. The substance has several pharmacological actions peripherally and also centrally. It is an antagonist of adenosine, a neuromodulator, blocking the actions of adenosine which are inhibitory (Hartley et al, 2001). Thus, caffeine has a stimulatory effect on the central nervous system. Typical doses of caffeine in day to day consumption are less than 500mg, while the toxic doses are more than 10 grams (James, 2004). Consumption of caffeine can have both negative and positive side effects and is predominantly individual and dose based.

Positive effects include protection against Parkinson's disease. Negative side effects include disruption of sleep, elevated blood pressure and elevated heart rate. Caffeine effects on blood pressure are a much controversial topic and several studies have been conducted to ascertain its role in elevating blood pressure and contribution to cardiovascular disease. This effect merits importance, because caffeine is consumed by many people worldwide and this includes populations who have hypertension.

In this essay, the effects of caffeine on blood pressure will be discussed. Discussion Caffeine is an adenosine antagonist. Adenosine is a neuromodulator and inhibition of adenosine causes increased activity of various other hormones like adrenaline, dopamine, cortisol and endorphins. At higher doses, caffeine can also cause inhibition of GABA neurotransmission leading to insomnia, anxiety and increased respiratory rate and heart rate. It crosses the blood-brain barrier and placental barrier readily because it is water soluble.

In the brain, it acts as a non-selective adenosine antagonist because of its structural similarity to adenosine (Dunwiddie and Masino, 2001). Some studies have shown that administration of caffeine in doses comparable to those consumed everyday can lead to acute elevation in blood pressure by 5-15 mmHg of systolic pressures and 5-10mmHg of diastolic pressures (James, 2004).. The effects pertaining to elevated blood pressures can last several hours in both sexes and in individuals of all age groups.

Another important finding in these studies is the fact that the effect is additive to that caused by other factors like smoking and stress. Effect of caffeine on blood pressure varies from individual to individual and elevations in blood pressure may be an individual susceptibility. Individuals who already have hypertension or borderline hypertension may be even more susceptible. Caffeine can also have synergistic action on blood pressure in times of psychological stress exaggerating the increase in blood pressure.

Thus, indirectly caffeine can contribute to cardiovascular disease (James, 2004). One interesting aspect is that the effects on blood pressure are inversely proportional to the number of portions consumed on a particular day. For instance, the initial portion of caffeine produces the greatest hemodynamic effect when compared to later portions (James, 2004). According to a study by James (2004), there is extensive evidence over the fact that consumption of caffeine in dietary doses increases blood pressure.

However, it is unclear whether this has an impact on cardiovascular disease because habitual use of caffeine leads to tolerance and epidemiologic findings regarding the impact of caffeine on cardiovascular disease is confusing. . Several experimental and epidemiologic studies have proven the impact of dietary caffeine on blood