The study, published in the journal JAMA, revealed that celiac disease was linked to increased risk of death from cardiovascular disease, cancer and respiratory disease.
Celiac disease is an autoimmune disorder, where gluten triggers the immune system to attack the gut.
"We have known that celiac disease can cause a number of long-term complications that can impact life expectancy, but this study examines an entire population in the most recent era, at a time when awareness of celiac disease and access to gluten-free food is widespread," said study first author Benjamin Lebwohl from Columbia University in the US.
"Despite this, we found that celiac disease is associated with long-term consequences," Lebwohl added.
Previous studies have demonstrated a modest but persistent increased risk of premature death in patients with celiac disease.
However, in recent years, more people with milder disease have been diagnosed and gluten-free food is widely available. It has therefore been hypothesised that celiac disease may no longer be associated with an increased risk of death.
Using nationwide data from Sweden's pathology departments, linked to national healthcare registers, researchers at Karolinska Institutet and Columbia University examined almost 50,000 patients with celiac disease and their risk of death.
Compared with controls, overall mortality was increased by 21 per cent in those with celiac disease. The relative increase in mortality risk was present in all age groups and greatest in those diagnosed in the age range of 18 to 39 years old.
Individuals with celiac disease were at increased risk of death from cardiovascular disease, cancer and respiratory disease.
Compared with controls, the overall mortality risk was greatest in the first year after diagnosis but the risk increase persisted beyond 10 years after diagnosis.
The increased risk was present also in patients diagnosed during recent years (2010-2017).
"Celiac disease is characterised by inflammation, which is generally bad for your health. I am therefore not surprised that we found an increased mortality for a number of causes of death in individuals with celiac disease," said " said corresponding and last author, Jonas F. Ludvigsson.
The fact that the relative risks were highest in the first year of follow-up can have several explanations, the researchers said.
"The intestinal inflammation is often most intense around diagnosis, and before a gluten-free diet has had an effect on mucosal healing. Another possible explanation is that the celiac diagnosis may have been made in patients who were very ill from other causes," Ludvigsson added.