1. The Effects of Antacids on Pepsin
Madeleine Finkenaur
The Academy of Notre Dame

2. Question
How much do antacids interfere with the stomach’s ability to breakdown food proteins?

3. Background Information
Food proteins are vital to the body and are broken down in the stomach by pepsin
Pepsin, a proteolytic enzyme in the stomach, requires a pH level of 1-3
This acidity is obtained by hydrochloric acid(HCl), which is secreted by the stomach
Antacids lower the acidity level of the stomach, making it difficult for food protein breakdown to occur

4. Hypothesis
The antacids will slightly hinder the food protein breakdown process in the stomach.

5. Materials 1 ml of Pepsin Distilled water Single dose of Pepto-Bismol
Single dose of Acid Reducer
650 mg of NaHCO3
7 150 ml beakers
electronic pH probe
stirring batton
mortar and pestle
10 ml Graduated cylinder
incubator at 37C
.1 Molar HCl
Single dose of Heartburn Relief
Single dose of TUMS
27 test tubes and holders
27 small hard-boiled egg pieces
pH strips
scale
pipets
chemical spoon
100 ml Graduated cylinder

6. Procedure
Make a 1% pepsin solution with 99mL of distilled water in a 150mL beaker
Make a 1% hydrochloric acid solution with 99mL of distilled water in a 150mL beaker
Take four test tubes and add 5mL of the pepsin solution and 5mL of distilled water in one, 5mL of the hydrochloric acid solution and 5mL of distilled water in another, 5mL of the pepsin solution and 5mL of the hydrochloric acid solution in the third test tube, and 10mL of distilled water in the last one
Crush a single dose of each antacid (TUMS, Pepto-Bismol, Acid Reducer, Heartburn Relief, and NaHCO3) separately with a mortar and pestle.
Add each antacid to a 150mL beaker with 100mL of hydrochloric acid

7. Procedure
Take five more test tubes and fill each one with 5mL of the 1% pepsin solution
Add 5mL of every one of the five antacid solutions to the five test tubes with the pepsin solution separately
Record the pH level of every test tube
Cut a small piece of hard-boiled egg for each test tubes and record the mass of each egg piece
Add the egg to every test tube and cover all the test tubes
Store all the test tubes in an incubator at 37C for 48 hours
Uncap all the test tubes after 48 hours and weigh the hard-boiled egg slices from each test tube and record
Repeat this procedure for three trials

8. Controls and Variables
Pepsin + Distilled Water, HCl + Distilled Water, Distilled Water, Pepsin + HCl
Independent Variable
Antacids: TUMS, Pepto-Bismol, Acid Reducer, Hreatburn Relief, Sodium bicarbonate(NaHCO3)
Dependent Variables
Percent of change in egg mass after the incubation period

9. Data

10. Data

11. Data Contents of Test Tube PH Level Distilled Water
6.5
Pepsin + Distilled Water 6
HCl + Distilled Water
1.5
Pepsin + HCl
TUMS
Pepto-Bismol
Acid Reducer
Heartburn Relief
NaHCO3 3

12. Data Antacid T-Test with Pepsin + HCl TUMS Pepto-Bismol Acid Reducer
Antacid
T-Test with Pepsin + HCl
TUMS
Pepto-Bismol
Acid Reducer
Heartburn Relief
NaHCO3

13. Post-incubation HCl + Distilled Water and Pepsin + Distilled Water
Pepsin + HCl and Distilled Water
NaHCO3
Acid Reducer and Heartburn Relief
TUMS and Pepto-Bismol

14. Conclusion
The hypothesis for this experiment was partly supported and partly rejected
TUMS was ineffective in breaking down food protein because it had pH level of 6
Pepto-Bismol was ineffective in breaking down food protein
Acid Reducer only had a mild amount of food protein breakdown
Heartburn Relief was very effective in food protein breakdown
NaHCO3 was ineffective in breaking down food protein

15. Conclusion Limitations Further Study
Only tested 5 antacids out of many
Some egg mass was lost when the egg was moved
Further Study
What are the effects of limited protein breakdown on the body?
Do more acidic food increase pepsin’s ability to breakdown food protein?

16. References
American Society of Health-System Pharmacists. (2010). Bismuth Subsalicylate . Retrieved from National Center for Biotechnology Information database.
Avraham, R. (2000). The Digestive System. Philadelphia: Chelsea House Publishers.
Carpi, A., Ph.D. (n.d.). Introduction. In Acids and Bases. Retrieved 2003, from Visionlearning database.
Gbemudu, A., PharmD. (n.d.). Antacid faq. In RxList [Fact sheet on Antacids]. Retrieved October 6, 2010, from
Gillson, S. (2010, April 16). H2 Blockers. Retrieved from About.com database.
Pali-Schöll, I., Herzog, R., Wallmann, J., Szalai, K., Brunner, R., Lukschal, A., Karagiannis, P., Diesner, S. C. and Jensen-Jarolim, E. (2010, July). Antacids and dietary supplements with an influence on the gastric pH increase the risk for food sensitization. Clinical & Experimental Allergy, 40(7), Abstract retrieved from
Pepsin. (2008). Retrieved from The Columbia Encyclopedia, Sixth Edition website:
Sexton, T. (n.d.). History of Antacid. Retrieved July 17, 2008, from Health & Wellness database.