Living Gluten-Free
by Tricia Thompson MS, RD, The Gluten-Free Dietitian
The Celiac Disease-Lactose Intolerant Connection
When they are newly diagnosed with celiac disease, many people also discover that
they are lactose intolerant and have difficulty digesting milk and products containing
milk.
This type of lactose intolerance is called “secondary lactose intolerance.” It is a
temporary form that develops as a result of celiac disease and resolves (in most
cases) as the intestine heals.
Lactose is a sugar found in milk. It is a “disaccharide” meaning it is made up of two
units of sugars. “Di” means two and “saccharide” means sugar. Specifically, lactose
is made up of one unit of glucose and one unit of galactose.
Disaccharides -- including lactose -- cannot be absorbed intact from the small
intestine. Instead they must be separated into single units of sugar
(monosaccharides). Enzymes that help do this are found in the small intestine.
When someone has lactose intolerance, lactose passes undigested through the
intestinal tract where it causes symptoms familiar to anyone who suffers from this
condition — diarrhea, gas and bloating.
But why does lactose intolerance develop in the first place?
The lining of the small intestine contains hair-like projections called villi. These villi
are lined by cells called enterocytes, and each one of them has smaller hair-like
projections called microvilli. These microvilli also are called the “brush border.”
Enzymes that help digest sugars (as well as break down products of protein) are
found in the brush border and are called “brush border enzymes.”
When you have celiac disease, the mucosa (or lining) of your small intestine is
damaged. Specifically, the villi become shortened or even completely flattened. This
results in a decrease in brush border enzymes.
Brush border enzymes include lactase which helps digest the sugar lactose found in
milk; sucrase which helps digest the sugar sucrose found in varying amounts in all
plant foods, including fruits, vegetables, and sugar cane; and maltase which helps
digest the sugar maltose found in cereal grains.
Should you also be concerned about sucrose and maltose intolerance?
Because the enzymes sucrase and maltase needed to digest sucrose and maltose
also are found in the brush border you may be wondering if you might have
secondary intolerances to these sugars.
I asked Dr. Stefano Guandalini, Director of the University of Chicago Celiac
Disease Center, to explain why this probably is not the case.
"The enzymes lactase, sucrase and maltase are all found in the brush border. Why is
it that lactose intolerance is common among persons with celiac disease but sucrose
and maltose intolerance are not?
"Among all disaccharidases (lactase, sucrase-isomaltase, and maltase), lactase is the
one of lowest abundance in the brush border membrane and is therefore the first to
be affected when there is a reduction of the intestinal absorptive area, such as in
untreated celiac disease."
How often do patients in your practice have secondary sucrose and/or
maltose intolerance?
"Even though the levels of sucrase-isomaltase and maltase may be reduced if
measured in the intestinal biopsies of newly diagnosed patients, this is essentially of
no clinical significance, as the remaining enzyme activity is plentiful to reach
effective digestion of those sugars. So the honest short answer is: never!"
If a patient suspects they may have a secondary intolerance to sucrose
and/or maltose what are your recommendations?
"Since these intolerances (if at all present) are by definition transient, the most
logical option is to substantially reduce the intake of these sugars for a period of time
adequate to allow for reconstitution of the normal enzyme activity. This time may be
different from person to person, but if the gluten-free diet is strict, I would assume
that in the majority of cases a few weeks should be more than sufficient."
In general how long does it take for lactose intolerance secondary to celiac
disease to resolve?
"Lactose intolerance (if present: in many patients, and particularly those who come
to the diagnosis with minimal GI symptoms, even lactose can be fully digested)
would persist until an adequate intestinal absorptive surface is reconstituted; again,
this is variable between different patients, but typically 2-3 months should be
enough to allow for regeneration of adequate amounts of lactase.
"I would like to add however that a substantial portion of adults present the so-called
“adult-type hypolactasia”; a genetically pre-programmed loss of lactase activity that
begins sometimes in mid-childhood. In these cases, obviously the intolerance won’t
regress. We have today the possibility to test for the existence of this genetic
condition via a simple blood test."
Thank you Dr. Guandalini!
For more information on lactose intolerance, please see the National Digestive
Diseases Information Clearinghouse web page on lactose intolerance.
Tricia Thompson, M.S., RD is a nutrition consultant, author and speaker specializing
in celiac disease and the gluten-free diet. She is the author of The Gluten-Free
Nutrition Guide (McGraw-Hill) and co-author of The Complete Idiot’s Guide to GlutenFree Eating (Penguin Group). For more information, visit
www.glutenfreedietitian.com.
This article was originally posted on diet.com
Copyright © 2008-2009 by Tricia Thompson, MS, RD