Rice forms sticky masses in the stomach that remove gastric mucus as they move through peristalsis, exposing the stomach lining to damage from acid and pepsin. This mucus removal can cause heartburn or ulcers. However, drinking water with rice can prevent this by turning the rice masses into a slurry rather than sticky masses, avoiding excessive mucus removal.

1. 430
Rice has been related to the formation of peptic ulcers (1,
2). For many people who do not eventually develop an
ulcer, it is also a common experience that having rice,
especially glutinous rice, may cause stomach discomfort
or heartburn. Studies carried out to understand the
underlying mechanism have been mainly focused on the
bran of rice (1). It has been found that bran oil becomes
ulcerogenic upon storage (1,2). The present work
attempts to approach this question in a different way,
offering an alternative explanation for the mechanism
and, on the basis of it, a suggestion as to how to minimize
the unwanted effect of rice.
The gastrointestinal tract is protected by its mucosa
epithelium and mucus layer, with the latter functioning
as a mechanical and chemical buffer as well as a lubrica-
tive (3). Mucin molecules, the major constituent of
mucus, are protein densely coated with oligosaccharides,
which afford the stickiness and viscosity. Starch, which
makes up most mass of rice, is polysaccharide. Upon
hydration through cooking, rice becomes sticky. When
rice is ingested into the stomach, it readily forms food
masses that are sticky. As the food masses move along the
stomach that undergoes peristalsis, the sticky rice takes
the sticky gastric mucus with it through adhesion.
Snowball effect results in removal of increasing amounts
of mucus from the stomach wall. Moreover, as the food
masses are mixed in this process, rice previously in the
middle of food masses is turned out and can bind more
mucus, while the mucus bound rice is moved into the
masses. Depending on the degree of stickiness and the
amount of rice, the end result can be an effective peeling
off of gastric mucus, making the stomach vulnerable to
the damaging power of gastric acid and pepsin, which are
all at their peak phase of secretion. Duodenum may be
affected in a similar way. Any kind of food will take a cer-
tain amount of mucus with it, and the stomach secretes
new mucus to meet its normal needs. Problems arise
when the removal of mucus becomes excessive and sur-
passes the speed of new mucus secretion. Accordingly,
glutinous rice would cause heartburn more readily than
nonglutinous rice does, which is consistent with the
experience of the general public, especially Asians.
On the basis of the above discussion, it becomes clear
that unrefined cereals, when compared with refined rice
and wheat, are associated with lower ulcer rates (2)
because bran reduces the stickiness. It is, however, not
necessary for rice eaters to give up their favorite rice and
shift to unrefined nonglutinous rice. A simple and effi-
cient solution is to drink enough water or other liquids
while having rice meal. Sufficient amounts of water can
convert rice masses into rice slurry in the stomach, which
is no longer able to remove large quantities of mucus.
Rice hurts the stomach by its
stickiness
X. Wang
Cornell University Medical College, New York, USA
Summary Rice masses remove mucus from the stomach and duodenum as the sticky starch binds the sticky
mucus, weakening the defense against acid and pepsin which may in turn cause heartburn and ulcer. Such unwanted
effect can be avoided by taking enough water with rice meal as water converts rice masses into slurry. © 2000
Harcourt Publishers Ltd
Received 22 June 1998
Accepted 22 March 1999
Correspondence to: Dr Xiao Wang, 450 East 63rd Street, Room 7G, New
York, NY 10021, USA. Phone: +1 212 223 0997; Fax: +1 212 421 1122
Medical Hypotheses (2000) 54(3), 430–431
© 2000 Harcourt Publishers Ltd
DOI: 10.1054/mehy.1999.0868, available online at http://www.idealibrary.com on

2. Unwanted effects of rice 431
© 2000 Harcourt Publishers Ltd Medical Hypotheses (2000) 54(3), 430–431
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2. Tovey F. I. Duodenal ulcer in China. J Gastroenterol Hepatol
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3. Wang X. Aspirin-like drugs cause gastrointestinal injuries by
metallic cation chelation. Med Hypotheses 1998; 50: 227–238.