Saturday, December 09, 2006

Lactose intolerance and hidden Celiac disease

Several studies have shown high incidence of lactose intolerance in Celiac disease. A study published in Digestion in 2005 confirmed that many lactose intolerant people also have undiagnosed Celiac. Almost a quarter of people had lactose intolerance as the only sign of hidden Celiac disease. All the lactose-intolerant people that did not get better with lactose avoidance had Celiac disease. I agree with their conclusion. All people suffering from lactose intolerance should be screened for Celiac disease. I would also include all people labeled as having IBS.

Lactose is milk sugar. A disaccharide or combination of the two simple sugars (monosaccharides) glucose and galactose, lactose digestion requires the intestinal enzyme lactase. Lactase is found on the tips of the villi of enterocytes, or small intestine lining cells, where it is vulnerable to injury. See my diagram, microscope slides, and explanation of villi on this blog and my website Lactose intolerance resulting from small bowel injury or abnormal gut bacteria is termed acquired or secondary lactose intolerance. Though there are many causes of small bowel injury, two of the most common are viral gastroenteritis, or “stomach flu”, and food intolerance. Lactase function can be also be impaired by abnormal bacteria levels in the small intestine known as small bowel bacterial overgrowth (SBO). Lactase enzyme levels also diminish with age.

Primary or congenital lactase enzyme deficiency is present in up to 80% of black Latinos, nearly 100% of Asians and Native Americans, but 15% of Caucasians of Northern European ancestry. Most of the latter are not lactose intolerant unless they have small bowel injury or SBO. Lactose intolerance in these individuals should raise the suspicion of Celiac disease (Celiac Sprue, non-topical Sprue and gluten sensitive enteropathy).

In my experience as a food allergy and intolerance expert, many lactose intolerant people as well as individuals labeled as IBS, are undiagnosed gluten sensitive individuals. After a gluten-free diet and associated gut healing they can tolerate dairy much better and many have improvement or resolution of IBS type symptoms. This is also my personal experience. In medical school, I diagnosed myself as having irritable bowel syndrome (IBS) and lactose intolerance.

Though, my blood tests for Celiac disease are negative I carry the major gene predisposing to Celiac, HLA DQ2, and have elevated stool antibodies to gliadin and tissue transglutaminase ( With a gluten-free diet my “IBS” resolved and my lactose tolerance dramatically improved. However, since I am intolerant to the milk protein, casein, I generally avoid dairy products. Casein or milk protein intolerance and milk or dairy allergy are distinctly different conditions from lactose intolerance.

If you have been diagnosed with IBS or lactose intolerance you should tested for Celiac disease.
Below I have included some helpful diagnosis codes.

Ojetti, V. et. al. High prevalence of Celiac disease in patients with lactose intolerance. Digestion 2005;71:106-110.

Heyman, M. Lactose intolerance in infants, children and adolescents. Pediatrics September 2006;118(3):1279-1286.

ICD9 diagnosis codes:
Lactose intolerance 217.3
Celiac disease/gluten sensitivity 579.0
Irritable bowel syndrome 564.1
Milk allergy V15.02
Other food allergies, not specified V15.05

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