One theory says, because of fighting with the English, the Irish had smaller portions of land to farm on. The portions of land being too small to grow enough wheat potatoes, which they could grow enough of, became the primary food in their diet. When the potato blight hit they were forced to switch to wheat. Their bodies no longer producing the enzymes to digest gluten they developed Celiac.
The following theory is a fun idea, however very little research shows the Romans never went as far north as Ireland. The Celts were hunter gatherers. Their digestive system was not used to a heavy grain diet. When the Romans (Italians) moved north they introduce wheat, also, as they returned south to Italy they took Celtic women as wives. This accounts for the Celiac disease in the Italians.
I found the idea fascinating, Celiac disease could potentially be traced through history or heritage. While the post were made by predominately Irish and redheaded persons there were also people who were British, Dutch, German and others holding to the idea that it is the fair skinned Europeans which tend to have this disease. Then one person said that her heritage was from the west of Spain and Puerto Rico. Another individual, although she is redheaded, and has green eyes, was asked by her doctor if she was Middle eastern because the Celiac population is predominately Middle eastern.
The issue needed more research than what I found in internet forums. Much of my information comes from abstracts of articles found on PubMed.gov a service of the U.S. National Library of Medicine and the National Institutes of Health.
In the Digestive and Liver Disease (an official journal of the Italian Society of Gastroenterology and The Italian Study of the Liver) the authors claim it's a global problem.
July 2004; 492-8
The abstract did not provide any percentages, but presented me with a new fact that this disease is a global problem.
This next article from the Turkish Journal Gastroenterology: official journal of Turkish Society of Gastroenterology said:
The prevalence of Celiac disease in the overall sample of Turkish children (1:111 or 0.9%) in this preliminary study is similar to that reported in European and Middle Eastern countries and the United States.
March 2008; 19(1): 14-21
This shows again, with the statement 'similar to that reported in European and Middle Eastern countries and the United States,' that is considered a global disease.
From Coeliac (European spelling) Society of Ireland website:
screening suggests that between 1 in 200 and 1 in 300 people of northern European extraction have Coeliac. It has been believed for a long time that Irish people have a higher than average risk of coeliac disease. Research in Northern Ireland (reported in 1998) suggests that as many as 1 in 122 individuals have coeliac disease.
Association of European Coeliac Societies website
The most important aim of the day is to make coeliac disease better known in Europe. AOECS represent more than 250000 diagnosed coeliacs from the 5 millions (1 % of the population).
In the past coeliac disease was regarded as a very rare childhood condition, but recent studies have shown that it is more common than previously thought. The incidence rate amongst the European population estimated around 1:100, in some countries (Finland, Hungary) even higher. Nowadays more adults are diagnosed than children and many of whom had no health problems during childhood, but develop symptoms only when adults.
I wanted to see a side by side study. I didn't find one, but I did find the following U.S. Information, regarding CD:
Prevalence of Celiac Disease in At-Risk and Not-At Risk Groups in the United States; A Large Multicenter Study
Given the common European ancestry of a large portion of the US population, it is likely that CD in the united States is more common than currently recognized.
See ARCH Med/VOL. 163 Feb.10, 2003 American Medical association. pg. 287
In the New England Journal of Medicine, Article Review, Medical Progress Celiac Disease:
Celiac disease occurs in nearly 1% of the population in many countries.
October 25, 2007; pg 1731; a pdf file of this article can be obtained at http://www.celiac.org
At the end of my studies I find that that Celiac disease, although genetic, is found in one percent of the world population. There isn't any correlation with having red hair, of being Irish, or being of Europeans decent as internet chatter may lead one to believe. This one percent had only one exception, the Arabic people of Saharawi, found in this following article.
Recenti Progressi in Medicina:
In the Arab people of Saharawi, the prevalence of celiac disease in children is so high (more than 5%) that this condition represents a primary health problem.
July- August 2001; 92 97-8): 446-50
I did this research back in September. The amount of information on the subject of Celiac Disease and the number of better written articles concerning the percentage of population with Celiac disease is far greater then the research I've done. This is a disease that is presently receiving a lot of attention. It is worth it for those with Celiac to do regular research in order to keep up with the changes in the worlds understand of this disease.