The Validity of Chocolate as an Aphrodisiac based on the effects on blood pressure from chocolate consumption and the viewing of attractive pictures

Stephanie Shreve, Zachary Mundt, Alicia Pope CU Boulder, Fall 2004

It has been claimed in many Cosmopolitan magazines, but is chocolate truly an aphrodisiac? Our curiosities lead us to test the merit of this rumor. Chocolate is a compilation of various ingredients, all with different digestion times and effects on the body. Which specific component of chocolate is the aphrodisiac? Aphrodisiacs cause arousal, but how are levels of arousal measured. Blood Pressure is a measure of the pressure in veins and artery caused by blood flow. If a person is aroused, will their blood pressure rise? We hypothesize that chocolate is an aphrodisiac and that percent changes in blood pressure will be an indication of arousal.

We used two women and two men to test our hypothesis. Each subject had their blood pressure recorded after being exposed to different treatments. First, their initial blood pressure was taken as a baseline from which to calculate percent differences from all the other treatments. This control was used to insure that the results came only from the treatments, not from a subject’s naturally high or low blood pressure. As a mechanism for arousal, the subjects were shown photographs of attractive people. There were corresponding sets of photos for the girls and the boys. Each set contained four photographs of people from fashion magazines. We measured each subject’s blood pressure after just looking at pictures, to find any arousal caused just by the pictures. After that recording, each subject proceeded to eat the same amount of milk chocolate. Their blood pressure was recorded again. Then, after eating the chocolate, the subjects viewed the pictures as their blood pressure was taken for the fourth time. These last two tests measure the immediate effects of chocolate in the body. These effects stem mostly from the large amount of sugar in chocolate because sugar is digested within minutes. To measure the extended effects of chocolate, we allowed an amount of time for further digestion before taking further blood pressure measurements. After researching digestion times for different foods, we decided on a thirty minute time lapse. Blood pressure was taken twice more, once with just the chocolate and once with the chocolate while viewing the photos. Overall we took five measurements in addition to the initial base-line blood pressure. The independent variables were whether or not chocolate was eaten, how much time had passed, and whether or not pictures were viewed. We tested these variables effect on percent change in blood pressure. To help eliminate error, we controlled the amount of chocolate eaten, the pictures viewed and activity levels. All subjects were sedentary between readings to prevent high activity levels from affecting blood pressure. We predict that the blood pressure of a person who consumes chocolate and then looks at pictures of attractive people will be more aroused, and therefore, have higher blood pressure, than a person who just looks at the pictures without eating chocolate.

Each treatment showed an increase in Blood pressure. In opposition to our hypothesis, the combinations of chocolate and pictures showed the smallest percent change from the initial blood pressure. Surprisingly, the largest percent difference came from just viewing the pictures alone, without eating any chocolate. Due to the large amount of treatments, we ran an analysis of variance which indicated no significant difference between any of our variables. A p value of .410 between just looking at pictures and viewing pictures immediately after eating chocolate showed no significant difference. A second p value of .915 showed even less significance between just viewing pictures and viewing the pictures after a thirty minute time lapse. The pictures, however, did prove to affect the arousal levels in blood pressure. In fact, just viewing the pictures alone, before eating any chocolate, resulted in the largest percent change in blood pressure from the base level initial pressure. So, the chocolate actually displayed a negative result in pressure, lowering the percent change from just the pictures alone.

The data is inconsistent with the predictions based on the hypothesis. Therefore, we reject our hypothesis and accept the null. According to the experiment, chocolate has no significant effect on blood pressure, and thus arousal levels. However, there were many sources of error throughout the experiment. Using an experimental group which only contained four subjects, the true nature of the effect of chocolate could not be determined. Also, each subject ate the same amount of chocolate, which does not account for body weight, composition, or time after their last meal. Another problem with the chocolate is that there are many ingredients that could have the aphrodisiac power. Sugar digests within minutes, which is where we noticed the smallest percent difference in Blood pressure. Possibly, the aspects of chocolate that affect arousal take longer to digest, and, therefore, longer to take effect on the body.

Problems also arose from the sphygmomanometer. Due to our inexperience with the equipment, measurements were difficult to take and the subjects experienced a decent amount of pain, which could affect blood pressure. Additionally, the selected photographs did not necessarily arouse the subjects. This experiment is based on high blood pressure equating to higher arousal levels. This is a possible error in the basis of our experiment. Possibly another method of measuring arousal would be more effective. Our experiment was similar to the Vincent et al 2002 experiment described on the cable web page which indicated no significant difference on blood pressure from emotions or physiological stress. We also tried to test the effects of emotion, in our case arousal, on blood pressure and found no significant difference. According to their experiment, other physiological stresses, such as the pain from the sphygmomanometer, does not significantly affect blood pressure.

Further testing should be conducted on the individual chemicals and hormones in chocolate. If these were separated, their individual effects could be measured separately as well. Also, possibly dark chocolate, which contains more cocoa, has more of an effect on arousal than milk chocolate. To incorporate more tastes, a wider variety of photographs or a more arousing situation should be presented. Also, the experimenters should be more experienced with the sphygmomanometer. Our hypothesis still holds many possibilities for further, more specific testing.