According to the American College of Gastroenterology, ulcers affect approximately 20 million Americans. Ulcers are regions where the lining has been destroyed by stomach acids or digestive fluids and enzymes; these can occur in the stomach or duodenum, the first part of the small intestine. Because these are sensitive areas of the body, in contact with digestive enzymes and acids, even small areas of damage can cause intense pain.

Predisposing factors to ulcer formation include: prolonged stress, skipping meals, being male, family history, cigarette smoking, coffee ingestion and presence of the bacteria Heliobacter pylori combined with a susceptibility or sensitivity in the immune system. (Abu Farsakh, 2002)

Acidity, Coffee and Ulcers

The intense acidity of both caffeine and coffee can stimulate the hypersecretion of gastric acids (Coffey, et al, 1986), (Borger, et al, 1976). People think decaffeinated coffee is healthier, but in terms of acidity, decaffeinated coffee has been shown to increase acidity to a greater degree than either regular coffee or caffeine alone. (Cohen and Booth, 1975) A study comparing the acid secretion of decaffeinated coffee with that of a high protein meal found that decaffeinated coffee was a more powerful stimulant of acid secretion than the meal. (Feldman, et al, 1981) Doctors recommend that people with ulcers restrict not only caffeinated but also decaffeinated coffee intake. (Marotta and Floch, 1991)

Coffee tends to speed up the process of stomach emptying, which may result in highly acidic stomach contents passing into the small intestine more rapidly than normal, increasing the risk of injury of the sensitive intestinal wall, thus increasing susceptibility for duodenal ulcers. (Glatzel and Hackenberg, 1967)

Stress, Caffeine and Ulcers

Increased levels of cortisol and other stress hormones stimulated by caffeine consumption and coffee drinking suppress the activity of the immune system and raise stress levels which are associated with ulcer formation.
GABA (Gamma-aminobutyric acid) is a neurotransmitter naturally produced in the brain and nervous system as well as the GI tract. It plays an important role in mood and stress management and it exerts a calming effect on the GI tract.

Caffeine has been found to interfere with binding of GABA to GABA receptors, preventing it from performing its calming function. (Roca et al, 1988) GABA’s role in stress management is also compromised in the presence of caffeine. This is significant as psychological stress has been shown to be an exacerbating factor in heartburn and ulcers. (Naliboff, et al, 2004)

Ulcers, Bacteria and Immunity

The presence of the bacteria Helicobacter pylori is implicated as a predisposing factor in ulcer development, but not everyone infected with H. pylori develops ulcers. It is unknown why this is the case, although a strong immune system provides protection against the bacteria’s ability to colonize damaged areas of the stomach lining. Chronically increased levels of stress hormones, such as the glucocorticoids, (which happens under stress or as a result of frequent caffeine or coffee intake) can suppress the immune system.

Chronic glucocorticoid elevation also interferes with the reactions of antigen-specific cell-mediated immune responses to the presence of bacteria, viruses, fungi, some tumors and other invading organisms. (Dhabhar and McEwen, 1997) Glucocorticoids can also cause cell death of a variety of lymphocytes, or white blood cells. (Wyllie, 1980),(Blewitt, et al, 1983), (Cidlowski, et al, 1996). This can create a situation in which the bacteria Helicobacter pylori can thrive in the stomach.

References (by alphabetical order)
Abu Farsakh, N.A. 2002. Risk factors for duodenal ulcer disease. Saudi Medical Journal. 23(2):168-72.
Blewitt, R.W., Abbott, A.C., and Bird, C.C. 1983. Mode of cell death induced in human lymphoid cells by high and low doses of glucocorticoid. British Journal of Cancer. 47(4):477-86.
Borger HW, Schafmayer A, Arnold R, Becker HD, Creutzfeldt W. 1976. The influence of coffee and caffeine on gastrin and acid secretion in man. Deutsche medizinische Wochenschrift. 101(12):455-7.
Cidlowski, J.A., King, K.L., Evans-Storms, R.B., Montague, J.W., Bortner, C.D., and Hughes, F.M. Jr. 1996. The biochemistry and molecular biology of glucocorticoid-induced apoptosis in the immune system. Recent Progress in Hormone Research. 51:457-90, 490-1.
Coffey, R.J., Go, V.L., Zinsmeister, A.R. and DiMagno, E.P. 1986. The acute effects of coffee and caffeine on human interdigestive exocrine pancreatic secretion. Pancreas. 1(1):55-61.
Cohen, S. and Booth, G.H. Jr. 1975. Gastric acid secretion and lower-esophageal-sphincter pressure in response to coffee and caffeine. New England Journal of Medicine. 293(18):897-9.
Dhabhar, F.S., and McEwen, B.S. 1997. Acute stress enhances while chronic stress suppresses cell-mediated immunity in vivo: a potential role for leukocyte trafficking. Brain, Behavior, and Immunity. 11(4):286-306.
Feldman EJ, Isenberg JI, Grossman MI. 1981. Gastric acid and gastrin response to decaffeinated coffee and a peptone meal. JAMA. 246(3):248-50.
H. Glatzel and K. Hackenberg, Effects of Caffeine Containing and Decaffeinated Coffee on the Digestive Functions: X-ray Studies of the Secretion and Peristalsis of Stomach, Intestines and Gallbladder, Medizinische Klinik, April 21, 1967; 62(16):625-28.
Marotta, R.B. and Floch, M.H. 1991. Diet and nutrition in ulcer disease. The Medical Clinics of North America. 75(4): 967-79.
Naliboff BD, Mayer M, Fass R, Fitzgerald LZ, Chang L, Bolus R, Mayer EA. 2004.The effect of life stress on symptoms of heartburn. Psychosomatic Medicine. 66(3):426-34.
Roca, D.J., G.D. Schiller, and D.H. Farb. 1988. Chronic Caffeine or Theophylline Exposure Reduces Gamma-aminobutyric Acid/Benzodiazepine Receptor Site Interactions. Molecular Pharmacology, May;33(5):481-85.
Wyllie, A.H. 1980. Glucocorticoid-induced thymocyte apoptosis is associated with endogenous endonuclease activation. Nature. 284(5756):555-6.