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The Celiac Disease-Lactose Intolerant Connection
posted at Diet.com by TriciaThompsonMS/RD @ 6:00am ET on September 30, 2008
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 Gluten-Free Eating (Penguin Group). For
more information, visit www.glutenfreedietitian.com.

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