The Effect of Carbonated Beverages on Human Physiology

The effect of carbonated beverages on human physiology

The class will be divided into three groups, roughly equal numbers in each group.

Group 1: Diet Coke has caffeine, but no sugar Group 2: Caffeine-free Coke, 7-Up, and Vernors have sugar, but no caffeine Group 3: Caffeine-free Diet Coke, Diet 7-Up, Diet Vernors and plain water have neither

You get to choose which group you are in. If you have any special medical condition or any other concerns about performing these operations, please see the instructor before lab. The procedure is simple.

1) Don't eat lunch! We need you somewhat in the post-absorptive (fasting) state. You can go hungry for a few hours!

2) Void your bladder just before lab. Record the time. You do not have to record the volume. Note: there are rest rooms on the ground floor near the greenhouse and also by the center stairwell on the basement and on the second floor. Make sure you wash your hands thoroughly afterwards with hot water and soap.

3) Measure your blood glucose level. You will receive specific instructions on procedure in lab. Make sure to clean your finger with the alcohol swab, first, and to use a clean, new lancet. Work over paper towels. Make sure you dispose of the lancet and all other items that contact blood in the special biohazard disposal bag. Be careful not to let your blood contact any non-disposable item in the lab and that you not contact any other people while either you or they are collecting the blood sample.

4) Drink 20 fluid ounces of the fluid appropriate for your group, about one and a half regular cans of soda. The reason for such a large quantity is to get larger results. If you can't finish that much, drink as much as you can.

5) About 45 minutes after drinking the fluid, measure your blood glucose level again. Make sure you wash your hands between steps 4 and 5! Note the special precautions listed in step 3.

6) About 1 1/2 hours after drinking the fluid, void your bladder again. This time, record both the volume and the time. Take a clean calibrated plastic cup to the restroom and, in the privacy of a booth, collect and measure the sample. After recording the volume, flush it down the toilet. Bring the empty cup back to the lab and dispose of it in the special biohazard disposal bag.

7) Report (under the proper group): original blood glucose level(mg/dl), change in blood glucose (mg/dl), urine production rate (ml/hour) Questions to consider for the report:

1) How much sugar is there in 20 fluid ounces of soda? Assume all is in the form of hexose -- if it isn't that way to start with, it will be after it gets through your digestive system! You can estimate the sugar level from the caloric content assuming 4 kcal/g.

2) Assume all the sugar ingested is absorbed within 45 minutes. This is reasonable if your stomach is already empty! How much would the sugar concentration in your body fluids change if that much sugar were: Dissolved and distributed in the blood plasma volume? Dissolved and distributed in the total extracellular volume? Dissolved and distributed in the total body fluid volume? Note the total body fluid is about 60% of the body weight (adult male). The intracellular fluid is about 5/8 of the total fluid, the extracellular about 3/8. The blood plasma is about 1/5 of the extracellular fluid, or 7.5% of the total fluid.

3) What was the average change in blood sugar level for those groups that ingested sugar (Group 2)? Is this consistent with the predicted change in concentration? If not, how do you explain what happened?

4) How much sugar would an inactive person metabolize in 45 minutes? If the sugar comes from the blood plasma, how much would you expect the concentration to change? How much did the blood sugar level change for those groups that did not ingest sugar (Groups 1 and 3)? Is this consistent with the predicted change? If not, how do you explain what happened?

5) Does caffeine affect the blood sugar level? Compare Group 1 versus Group 3: both without sugar, one with and one without caffeine. What is the mechanism?

6) Does caffeine affect urine production? Again compare Groups 1 and 3. What is the mechanism?

7) Does sugar affect urine production? Compare Groups 2 and 3: both without caffeine, one with and one without sugar. What is the mechanism? Hint: compare the osmotic pressure of coke (assuming all the sugar is hexose) with the osmotic pressure of body fluids. What is the effect of drinking a hypertonic solution?