A Minnesota study using frozen blood samples taken from Air Force recruits 50 years ago has found that intolerance of wheat gluten, a debilitating digestive condition, is four times more common today than it was in the 1950s.
The findings contradict the prevailing belief that a sharp increase in diagnoses of wheat gluten intolerance has come about because of greater awareness and detection, and raises questions about whether dramatic changes in the American diet have played a role.
"It's become much more common," said Dr. Joseph Murray, the Mayo Clinic gastroenterologist who led the study. No one knows why, he said, but one reason might be rapid changes in eating habits and food processing over the last half century.
"Fifty years is way too fast for human genetics to have changed," Murray said. "Which tells us it has to be a pervasive environmental influence."
Researchers at the Mayo Clinic and the University of Minnesota who conducted the study also found that the recruits who had the undiagnosed digestive disorder, called celiac disease, also had a four-fold increase in the risk of death.
Today an estimated one of 100 people suffer from the inherited disorder, though most of the time people don't know they have it.
The disease occurs in people whose bodies cannot digest gluten, a protein found in wheat, rye and barley. The undigested protein triggers the body's immune system to attack the lining of the small intestine, causing diarrhea, nausea and abdominal pain. Though people live with it for many years, over time it destroys the lining of the small intestine, leading to an inability to absorb nutrients such as iron and calcium. That, in turn, causes serious problems, including anemia, osteoporosis and even infertility.
The only treatment is a gluten-free diet -- no wheat, rye or barley.
Murray said he initiated the study to find out whether the disease is on the rise, and whether it had long-term health consequences if undiagnosed and untreated.
He turned to medical archaeology to find the answers - a treasure-trove of blood samples taken from recruits at the Warren Air Force base in Cheyenne, Wyo., between 1948 and 1954. At the time, strep infections were raging among the recruits, mostly young men on their way to fight in the Korean war. Doctors there drew the samples as part of a study that proved treating the infections with antibiotics would prevent rheumatic fever, a serious heart ailment that can follow strep throat.
One of the doctors in that study took some of the samples with him when he moved to the Cleveland Clinic in Ohio. When he decided to retire two decades ago, he asked Dr. Edward Kaplan, a strep specialist at the University of Minnesota, to become their guardian. The vials were transported in frozen-pizza delivery trucks to Minneapolis, where they reside today.
"Nobody has anything like it," said Kaplan. "There are other collections, but none go back this far."
In 2000 they were used to help resolve an intense debate among researchers over whether hepatitis C infection meant certain death, or whether many people could live with it for years.
Murray used a similar design for the study on celiac disease, published today in the journal Gastroenterology. He tested more than 9,133 samples for the antibodies that proved the recruits had celiac disease; 43, or about one out of 652, had the disease. He then tested blood samples from groups of men from Olmsted County, more than 12,000 in all. In an older group of men, one in 121 tested positive, and in the younger group one in 106 tested positive, an increase of four to four-and-a-half times.
His findings raise questions about why the number of people with the disease has grown so fast. But rates of other immune diseases have also increased a lot. One theory is that modern, clean living, which has resulted in fewer infections, parasites and microbes in our bodies, causes the immune system to turn on healthy tissue instead. Or it might be the modern diet, Murray said.
"The types of food we eat now are different," he said.
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