Question: Does the caffeine in Coca-Cola affect blood pressure? Hypothesis: The amount of caffeine in Coca-Cola will cause to the adrenal glands, located on the top of the kidneys, to release more adrenaline which will in turn cause an increase in blood pressure. As the amount of Coca-Cola decreases, so will the difference between initial blood pressure and blood pressure after the consumption of the caffeine.
Procedure: In order to test my hypothesis, I decided to use a common caffeinated beverage, Coca-Cola. The amount of caffeine in each bottle is given as 48mg/500mL. So, to keep my calculations clean my initial test was with 500mL of the Coca-Cola. I took my blood pressure with a Vermier Labquest before I consumed any caffeine to have a control variable. It was a manual blood pressure monitor, so I took my own blood pressure. After placing the cuff on my arm, I squeezed the bulb until the cuff pressure reached 170 mm Hg. Then, I released the bulb and let the pressure drop until it was 50 mm Hg and I used the release valve on the bulb to completely release the pressure and stopped the data collection.
This data was recorded. Next, I measured the amount of the Coca-Cola used for the current test into a measuring cup and then consumed it. I waited 20 minutes after consumption to take my blood pressure again. Caffeine has been reported to take affect after a time period of 15-45 minutes. I did an identical test every day for five consecutive days with varying amounts of Coca-Cola consumed. On the first day, I consumed 500mL, 400mL on the second day, 300mL on the third day, 200mL on the fourth day, and 100mL on the fifth day. I recorded my blood pressure pre-caffeine consumption on each day.
* Spike in blood pressure during the third trial could also be due to the additional consumption of food during the time between initial blood pressure data collection and post-caffeine consumption data collection. No other trials had outside influences on data.
The following is a line graph that represents the systolic pressures of each trial before and after caffeine consumption:
There are noticeably great differences between the different trials up until the fourth trial when the systolic pressures seem to be nearly the same. The pressure at trial three seems to be an outlier. The following is a line graph that represents the diastolic pressures of each trial before and after caffeine consumption:
The correlation between the diastolic pressures does not go along with my hypothesis in showing that the blood pressure will rise as the caffeine intake rises. The spike at trial three is also an outlier here like it was with the systolic pressures. Both of these graphs help to illustrate the change in the pressures visually. Conclusion: Although there is some relation between caffeine intake and a rise in blood pressure, my data was not one-hundred percent accurate in showing that the more caffeine consumed the more of an increase. This would have been shown had the data for trial three been less of an extreme. If the systolic pressure had fallen between 117 and 129 (The systolic pressures for trials 4 and 2) then the data would appear to be much more consistent.
The cause of this could be directly due to the fact that I was also eating at the time of the trial whereas with the other four tests, the only thing that I was ingesting at that point in time was the Coca-Cola. I chose to do this experiment on myself for that very reason: I can control my consumption and I am aware of everything consumed that may or may not affect the outcome of the data. If I were to redo this entire experiment, I would also choose to use myself as the test subject. This keeps my variables to a minimum and ensures uniformity.
I would also make sure that at the time of the trials that nothing but the actual product, in this case Coca-Cola, was being consumed; especially in the time period between consumption of the test product and then the second blood pressure reading. I would also change my equipment. The blood pressure monitor that I used was manual and at times very unreliable. If given the opportunity to redo this, I would purchase a digital blood pressure cuff that would insure that each reading could not be the product of operator error. This could have also been a factor that led to the outlying data for trial three.
Time between consumption and taking a blood pressure reading could also be altered. I used twenty minutes due to the fact that it is a short amount of time and I would not have to worry about controlling possible outside factors for a long period of time. However, if I had let the caffeine be in my system for up to 45 minutes, there may have been more of a noticeable effect to the change in my blood pressure.
My hypothesis that the amount of caffeine in Coca-Cola will cause to the adrenal glands, located on the top of the kidneys, to release more adrenaline which will in turn cause an increase in blood pressure. As the amount of Coca-Cola decreases, so will the difference between initial blood pressure and blood pressure after the consumption of the caffeine was somewhat proven to be right. Yes, blood pressure did rise each and every time that I drank the Coca-Cola. However, the latter portion of the hypothesis is still unclear. It is unclear due to the data collected in trial three thus the need to redo trial three for an accurate confirmation of my hypothesis.