Department of Nutritional Sciences - University of Toronto

#UofTGrad17 Joseph Jamnik: Getting a Grip on Gluten

Jun 9, 2017

Joseph JamnikJoseph Jamnik Researchers estimate that up to 300,000 Canadians might have celiac disease, but the vast majority of them have never been diagnosed and likely don’t know they have it. That was one conclusion Joseph Jamnik drew from his doctoral research, which he and his colleagues will publish over the next few months.

Jamnik was a graduate student in the lab of Ahmed El-Sohemy, a professor in the Department of Nutritional Sciences at the University of Toronto who holds the Canada Research Chair in Nutrigenomics. He received his doctoral degree yesterday at Convocation Hall.

Over the summer, Jamnik will wrap up his research on gluten then start medical school at U of T in the fall. He spoke with Faculty of Medicine writer Jim Oldfield about his research and what he’s learned about gluten and health.

Tell me about your PhD research.

Broadly, I looked at gluten-related disorders in the Canadian population, by analyzing data from the Toronto Nutrigenomics and Health study and the Toronto Healthy Diet study. This represented nearly 3,000 adults living in Toronto, which enabled us to conduct some unique analyses because the population was so ethnically diverse. For example, we found that most people with celiac disease are Caucasian. That has been shown elsewhere, but we were able to confirm it in a Canadian population. We also found that certain groups such as East Asians have a very low prevalence — likely due to lower genetic susceptibility and diets that are low in gluten. Overall, we found the prevalence of celiac disease in Canada is high, roughly one percent of the population, which is similar to findings in the U.S. Most significantly, 85 per cent of that group had not been diagnosed.

What’s the importance of those findings?

Some people with celiac disease who are undiagnosed suspect they are gluten-intolerant and may have modified their diets accordingly. But it appears that many have no idea they have the condition — increasingly, physicians are seeing people with the disease who have no gastrointestinal symptoms. Celiac disease is a serious condition that is sometimes associated with other autoimmune disorders such as arthritis and diabetes. People with untreated celiac disease may also have an increased risk for osteoporosis, infertility and even certain cancers. Some studies have shown that early diagnosis and avoidance of gluten limits damage to the small intestine and reduces risk for these other conditions.

What’s involved with an accurate diagnosis?

For an official diagnosis you need a clinical workup, although the patient must be consuming gluten. One of the most common antibodies clinicians assess in blood tests is tissue transglutaminase (tTG). There are also genetic tests that can be used to rule out celiac disease — people with the condition carry one or both of the HLA DQ2 and DQ8 genes, although many people without celiac disease also have these variants. If blood tests come back positive for tTG, some people will just try a gluten-free diet and see how they feel. Others will choose a biopsy of the small intestine, which looks for damage to the villi, the small projections that line the intestine and enable nutrient absorption. Biopsy is the only way to confirm a diagnosis, either right away or by comparing the initial biopsy results with a second sample taken when the patient has been off gluten for some time.

Did you look at non-celiac gluten sensitivity?

That is another disorder we are studying. It’s an emerging area of research, and the jury is still out on whether the condition exists and what effects it may have on health. These patients may have celiac-like symptoms, but they don’t test positive for celiac disease. While it’s possible that gluten could be causing these symptoms, some people might just feel better after going gluten-free because they’re cutting excess processed foods from their diet. Although we’ve seen a big surge in popularity of the gluten-free diet, we have a very limited understanding of how gluten affects individuals without celiac disease on a physiological level. Our lab investigated the effects of gluten intake in people without celiac disease by looking at blood plasma proteins. We identified physiological pathways associated with gluten intake, some of which may become dysregulated in people reporting adverse symptoms in response to gluten. But this needs further study. It's important to remember that a gluten-free diet isn't recommended for most people since many foods that contain gluten are good sources of fibre and other nutrients.

Is there a particular diet or way of eating that you generally recommend?

Diet is very individual. Preferences can be based on cultural practices, and taste perception plays a big role as well, which is another area our lab is studying. But generally, it’s best to eat minimally processed foods and watch the portion size, but also consider foods you enjoy. That way, you’re more likely to stick with them over time. As genetic tests become more available, people will make more decisions on what to eat based on individual genetic profile. Research from our lab and others has found that genetics play a role in how people metabolize caffeine and vitamin C, to take just two examples. This is a really exciting area of research that is sure to produce more fascinating results.