Drinking coffee, both regular and decaffeinated varieties at any temperature, increases your body’s production of gastrin, which is a hormone that stimulates the secretion of gastric acid in your stomach. Gastric acid is necessary for proper digestion and absorption of food, but too much can lead to gastrointestinal diseases. Higher caffeine content has a greater impact on gastrin, which partially explains why heavy coffee drinkers experience more gastrointestinal problems. Consult with your doctor if you have chronic stomach or intestinal problems.
Gastrin
Gastrin is synthesized by G-cells, which are located in the gastric pits of your stomach, and acts to regulate gastric acid secretion and promote the growth of gastric mucosa, according to the book “Advanced Nutrition and Human Metabolism.” Once produced, gastrin binds to parietal cells along with histamine and acetylcholine, and hydrochloric acid is produced. The primary stimulus for gastrin secretion is the presence of certain nutrients, especially peptides, certain amino acids and calcium, in the gastric lumen. Compounds in coffee, wine and beer are particularly potent stimulants. Secretion of gastrin is inhibited when the pH of your stomach becomes very low, usually between 2 and 3.
Coffee and Gastrin Production
According to an Italian study published in a 1986 edition of the “Journal of Clinical Gastroenterology,” drinking at least two cups of brewed coffee causes prompt and lasting elevation of serum gastrin levels. The researchers noted that both caffeinated and decaffeinated coffee affect gastrin production, although the caffeinated variety has greater impact. Specifically, two cups of regular coffee increased gastrin levels 2.3 times above normal, while the same amount of decaffeinated coffee increased it by 1.7 times. The researchers concluded that neither distension, osmolarity, calcium nor amino acid content accounted for the rise in gastrin, so it must be due to an unidentified ingredient within coffee that is only partially destroyed during the process of caffeine removal.
Coffee and Gastrointestinal Function
The increased production of gastrin and gastric acid from coffee consumption can cause gastrointestinal problems. According to a Dutch study published in a 1999 edition of the “Scandinavian Journal of Gastroenterology,” coffee promotes acid-reflux disease, induces gallbladder and colon contraction and may slow stomach emptying, but it is not associated with dyspepsia in the scientific literature. Further, the amount of acid-reflux can be reduced by drinking decaffeinated coffee. Excessive gastric acid production is linked to stomach and intestinal ulceration. The researchers concluded that since coffee contains no calories and its affect on the gastrointestinal tract cannot be attributed to volume, acidity or osmolality, it must cause pharmacological effects in addition to those of caffeine.
Affect of Coffee Temperature
According to a study published in a 1989 edition of the “American Journal of Clinical Nutrition,” the consumption of caffeinated coffee greatly increases gastrin and gastric acid production, but the temperature of the coffee has no additional effects on serum gastrin concentrations. The researchers tested steaming hot, warm and cold coffee and found no significant difference.
References
- “Advanced Nutrition and Human Metabolism”; Sareen Gropper et al; 2009
- "Journal of Clinical Gastroenterology"; Effect of Regular and Decaffeinated Coffee on Serum Gastrin Levels; F. Acquaviva et al; April 1986
- "Scandinavian Journal of Gastroenterology"; Coffee and Gastrointestinal Function: Facts and Fiction: A Review; P. J. Boekema et al.; July 1999
- "American Journal of Clinical Nutrition"; Gastric Acid Secretion, Gastrin Release, and Gastric Emptying in Humans as Affected by Liquid Meal Temperature; K. E. McArthur et al.; January 1989
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