Italian researchers report that some people who think they are lactose-intolerant may actually suffer from a psychological condition known as somatoform disorder.
With true lactose intolerance, a person is deficient in the enzyme lactase, which breaks down the lactose in dairy products. Those who suffer it say they experience bloating, gas, gut pain and nausea when they eat or drink products containing the milk sugar lactose.
Somatoform disorder describes a group of conditions in which the physical pain and symptoms a person experiences are really related to psychological factors.
This new study shows that some people "should not blame lactose for symptoms of lactose intolerance," said Guido Basilisco, MD, a researcher in the gastroenterology unit at IRCCS-Ca Granda, in Milan.
He presented the findings at Digestive Disease Week in Chicago.
In the study, Dr. Basilisco and his colleagues evaluated 102 patients, 77 of them female, who took a breath test commonly used to identify lactose intolerance. Patients also completed a questionnaire about somatization, anxiety and depression.
Those with somatoform disorder often report multiple problems in different areas of the body, such as faintness or weakness of a body part, Dr. Basilisco said, but no physical cause can be found.
Either lactose intolerance or malabsorption was identified in 29% and 33% of patients, respectively. However, when Dr. Basilisco looked at those with what he calls altered somatization," he found that patients with altered somatization are four times more likely to report lactose intolerance."
It means there is strong link between the two conditions, he said. Merriam-Webster defines somatization as the existence of physical complaints in the absence of a known medical condition.
Those who reported they were intolerant were also more likely to be anxious, but that link was not as strong.
Dr. Basilisco plans to look at why some patients focus on food as the cause of their symptoms.
The findings didn't surprise Mary Maish, MD, surgical director of the Center for Esophageal Disorders at the University of California, Los Angeles. She has seen the same connections in her patients.
"It's a real thing, they really do have these symptoms," she said. Most experts in the field, she said, do think many of the symptoms linked with what is called lactose intolerance are probably more related to other kinds of psychological issues that have not been addressed. "It's good to see some science behind it."
Dr. Maish said it might help for doctors to refer to the study when talking to some patients. With that as an introduction, she said, doctors could then investigate other avenues to helping reduce psychological symptoms.
Patients can then focus on the real root of the problem and get back to eating dairy, she added.
That's important because not eating dairy products raises the risk of calcium deficiency and osteoporosis, the researchers noted.