According to a study by Dr. Joseph Romagnuolo, a gastroenterologist who is completing studies in clinical epidemiology at McGill University in Montreal, mild hyperhomocysteinemia occurs in five to seven percent of the healthy population, but it runs as high as 16 per cent among patients with IBD.

Homocysteine is an amino acid formed during the metabolism of ethionine. Elevated levels of the product more than triple a person's risk for deep vein thrombosis (DVT) and double the risk of coronary artery disease. Dr. Romagnuolo's study, which was conducted at the University of Alberta in Edmonton involved 64 patients, 56 with Crohn's disease and eight with ulcerative colitis. Their mean age was 42 and the mean length of disease duration was 12 years.

"There are many reasons why you might want to look for high homocysteinemia in IBD patients, both for complications such as thrombotic events, and because it might predispose them to other conditions," Dr. Romagnuolo said.

Normal homocysteine levels are 12.1 micromol per ml, but in the study group, 10 had levels that were higher than that; one patient's homocysteine was considered significantly elevated -- it was greater than 20 micromol per ml.

People who are deficient in vitamins B12 and folate frequently have high homocysteine. However, Dr. Romagnuolo said it was interesting that in his study, only five subjects were vitamin B12 deficient and none were folate deficient.

"And yet we found 10 with hyperhomocysteinemia, so there seems to something that leads to high homocysteine levels apart from vitamin deficiency," he said. Dr. Romagnuolo explained that although the link between vitamin deficiency and hyperhomocysteinemia is not new, he could not say that there was any association between homocysteine levels and disease severity. Also, he said, because of the small number of patients involved, it is difficult to draw any conclusions about the risk of thrombotic events.

"We had five with deep vein thrombosis, one with pulmonary embolism, one with stroke and deep vein thrombosis together." It's also interesting to note that while osteopenia and osteoporosis are both common in people with IBD (33 per cent and 11 per cent respectively), this is probably not related to homocysteine levels.

"If you look at patients with a genetic defect who have osteoporosis, they usually have a high level of homocysteine in their blood and we wanted to know whether this was why people with IBD get osteoporosis and osteopenia," he said. "Up until now there have been a lot of theories, but nobody knows why."

Similarly, he said, there didn't seem to be any significant association between surrogate markers of disease activity including steroid use, previous resections and the use of immunomodulators such as methotrexate, he said.

"We looked at smoking because smoking is associated with Crohn's disease and lower levels of B6 and there is a trend toward higher homocysteine levels if you smoke or have a history of smoking," he added. Dr. Romagnuolo said people with IBD would be advised to maintain healthy diets as a matter or course, but this should emphasise the fact that they need to supplement their diets with multi-vitamins, particularly those containing folate.

The condition could ultimately have important clinical implications in the pathogenesis, treatment and prediction of thrombotic events, but clearly more study is needed in these areas, he said.