Using a UK database of electronic medical records, he and his colleagues identified 367 children and adults diagnosed with Crohn's disease and 591 diagnosed with ulcerative colitis between 2005 and 2008. The researchers matched each of those people to five IBD-free individuals the same age and sex.
They then used air-quality data from government monitors to assess the average yearly levels of three air pollutants in the study subjects' residential areas.
The pollutants included nitrogen dioxide, which is produced largely by vehicles and is highest in urban, high-traffic areas; sulfur dioxide, which is produced through industrial processes, including the burning of coal and oil; and particulate matter, fine particles emitted via car exhaust, as well as power plants and other industrial sources.
Overall, Kaplan's team found no association between IBD and the three air pollutants across the study group as a whole.
However, young people — those age 23 or younger — were about twice as likely to be diagnosed with Crohn's disease if they lived in a region in the top 60 percent of nitrogen dioxide levels, versus the bottom 20 percent.
Similarly, people age 25 or younger were twice as likely to have ulcerative colitis if they lived in areas with higher sulfur dioxide levels. However, there was no evidence of a “dose-response” relationship — that is, the risk of ulcerative colitis climbing steadily as sulfur dioxide levels rose.
That lack of a dose-response, Kaplan told Reuters Health, “makes us a little more cautious about that finding.”
Indeed, he urged caution in interpreting the findings as a whole. While he and his colleagues tried to account for other factors — such as study subjects' smoking habits and socioeconomic status — they cannot rule out the possibility that something other than air pollution itself accounts for their findings.
“This is an interesting association,” Kaplan said. But, he added, the findings do not prove cause-and-effect.
As for why air pollution would affect IBD risk, Kaplan said he could only speculate, based on research into other health conditions, including heart and lung disease. Studies indicate that air pollutants can trigger inflammation in the body; that, Kaplan explained, raises the possibility that in genetically predisposed people, air pollution may trigger an inflammatory response in the intestines that leads to IBD.
Since the current study found a relationship between pollutants and IBD only in young people, the findings also raise the question of whether children and teenagers are particularly susceptible to any effects of air pollution on the risk of the digestive disorders.
Much more research is needed, Kaplan said — both larger population studies and research in animals to see how exposure to various air pollutants might affect intestinal health.
He added that no one is proposing that air pollution is the environmental cause of IBD; if it does turn out to be a factor, he said, it will likely be one of many players.
But if air pollution is confirmed as a risk factor, there would be important implications, Kaplan said, since air quality is something that can be modified.
Eating more olive oil could help prevent ulcerative colitis, according to a new study co-ordinated by medical researchers at the University of East Anglia (UEA).
Presented today at the Digestive Disease Week conference in New Orleans, the findings show that people with a diet rich in oleic acid – which is present in olive oil –are far less likely to develop ulcerative colitis. Oleic acid is a monounsaturated fatty acid found in olive oil, peanut oil and grapeseed oil, as well as in butter and certain margarines.
The researchers, led by Dr Andrew Hart of UEA's School of Medicine, studied more than 25,000 people aged 40-65 living in Norfolk, UK. The volunteers were recruited to the EPIC study (European Prospective Investigation into Diet and Cancer) between 1993 and 1997. The participants, none of whom had ulcerative colitis at the outset, completed detailed food diaries which were later analysed by specially trained nutritionists working in Cambridge.
By 2004, 22 participants in the study had developed ulcerative colitis and the researchers compared their diets with those who did not develop the disease. They found that those with the highest intake of oleic acid had a 90 per cent lower risk of developing the disease.
“Oleic acid seems to help prevent the development of ulcerative colitis by blocking chemicals in the bowel that aggravate the inflammation found in this illness,” said Dr Hart.
“We estimate that around half of the cases of ulcerative colitis could be prevented if larger amounts of oleic acid were consumed. Two-to-three tablespoons of olive oil per day would have a protective effect,” said Dr Hart.
Ulcerative colitis is a distressing disease affecting 120,000 people of all ages in the UK and 1 million in the US. It is characterized by inflammation of the lining of the colon or large bowel, which causes abdominal pain, diarrhoea and weight loss.
Similar work in other countries is now required to determine if these results are reproducible there, before the link can be said to be definite. If it is confirmed that oleic acid is truly protective, dietary modifications should be considered to prevent colitis. Additionally, the use of oleic acid supplements should also be assessed in the future as a possible treatment for colitis sufferers.
Researchers aren't sure why there could be a link between the mode of delivery and celiac disease, but one possible explanation is that children born via C-section don't pick up the same microbes from their mothers as babies that pass through the vaginal canal, Hornef said. This alters the infant's colonization with gut microflora, or “good” microbes, that aid in digestion and fending off pathogens.
Previous research suggests there are differences in the intestinal bacterial flora between children born vaginally or by C-section.
“We are only beginning to understand the complexity of the host-microbial interaction at the intestinal mucosa, and it is difficult to make firm conclusions at this stage,” Hornef said.
Does any of this suggest that women with a personal or family history of celiac disease avoid C-sections? According to both Green and Hornef, it's too early to make firm recommendations.
“I think our data are not evidence enough to already make a medical recommendation, but rather they shed light on a possibly ill-studied issue,” Hornef said. “The data first need to be confirmed.”