Montréal researchers find a link between pollutants and certain complications of obesity
This breakthrough could eventually help improve prevention, diagnosis and treatment of cardiometabolic complications associated with obesity
A team of researchers at the IRCM in Montre’al led by Re’mi Rabasa-Lhoret, in collaboration with Je’rome Ruzzin from the University of Bergen in Norway, found a link between a type of pollutants and certain metabolic complications of obesity. Their breakthrough, published online this week by The Journal of Clinical Endocrinology & Metabolism, could eventually help improve the prevention, diagnosis, and treatment of cardiometabolic risk associated with obesity, such as diabetes, hypertension and cardiovascular disease.
Although obesity is strongly linked to insulin resistance and type 2 diabetes, a subset of obese individuals, termed “metabolically healthy but obese”, appears relatively protected from the development of such cardiometabolic complications. IRCM researchers are studying the factors that seem to protect obese individuals who remain metabolically healthy, in an attempt to find therapeutic avenues to prevent complications for others who are at risk.
“Recently, persistent organic pollutants (POPs) have been found to accelerate the development of prediabetes and obesity in mice, thereby mimicking the unfavourable cardiometabolic profile characteristic of certain obese individuals,” says Re’mi Rabasa-Lhoret, MD, PhD, endocrinologist and Director of the Metabolic Diseases research unit at the IRCM. “As a result, the aim of our study was to test whether metabolically healthy but obese individuals have lower circulating levels of POPs than obese individuals with cardiometabolic complications.”
Persistent organic pollutants are man-made chemicals used in agricultural, industrial and manufacturing processes. Due to their toxicity, POPs have been strictly and internationally regulated to ensure public health. However, because they have the ability to resist environmental degradation, POPs can still be found all around the world, even in areas where they have never been used, and remain omnipresent in our environment and food products. Thus, virtually all humans are exposed to POPs daily.
“Exposure to POPs comes primarily from the environment and the consumption of food such as fatty fish, meat and milk products,” explains Je’rome Ruzzin, PhD, expert in the field of research on POPs. “One important characteristic of POPs is their lipid solubility, meaning they accumulate in the body’s fatty tissues. As their name suggests, they are also persistent so the body cannot easily eliminate them. POPs can therefore have significant impacts on human health, and have been shown to affect reproduction, promote cancer, and be involved in the development of metabolic diseases.”
Complications of obesity
The major diseases associated with obesity are hypertension, atherosclerosis, and diabetes, as well as certain types of cancer. Less well-known complications include hepatic steatosis, gallbladder disease, pulmonary function impairment, endocrine abnormalities, obstetric complications, trauma to the weight-bearing joints, gout, cutaneous disease, proteinuria, increased hemoglobin concentration, and possibly immunologic impairment. A U- or J-shaped curve illustrates the relation between body mass index and the degree of these various complications. This relationship can be used to provide guidelines for assessing treatment of obesity.
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Ann Intern Med. 1985 Dec;103(6 ( Pt 2)):1052-62.
IRCM researchers conducted a study of 76 obese women of similar age, body mass index and fat mass index, in which they analyzed the concentration of 21 POPs, as well as cardiometabolic risk factors. Among 18 detectable pollutants, the women with cardiometabolic complications had higher concentrations of 12 POPs.
“Remarkably, close to 70 per cent of the detectable POPs were significantly higher in individuals with cardiometabolic complications compared to metabolically healthy but obese subjects,” adds Marie-Soleil Gauthier, PhD, co-first author of the study and research associate at the IRCM. “Our study confirms that the two groups have distinct POP profiles, and that metabolically healthy but obese individuals have significantly lower circulating levels of various classes of POPs than patients with complications. A better understanding of the role of POPs could lead to new directions for the prevention, diagnosis, and treatment of cardiometabolic risk associated with obesity.”
“Although this study does not show a causal link, it suggests that pollutants found abundantly in our environment could promote the development of cardiometabolic diseases like diabetes,” concludes Dr. Rabasa-Lhoret. “If future studies confirm this increased risk, such observations could have a significant impact on public health decisions because we will need to dramatically reduce our exposure to these pollutants.”
What are the Complications of Obesity?
Who would not like to look thin? Going to a wedding or reunion? Want to get into those jeans that fit so well just a few years ago? We cannot escape the changes that happen to our body over the years. But being overweight has consequences beyond how we look or how we might not fit into old clothes. Obesity is a disease because it can shorten your life and because it causes complications. Obesity causes problems with your body, your metabolism, and your mental health. Let’s discuss some of the problems caused by obesity.
People with higher weights have shorter lifespans. If a person is obese at the age of 40, life will be shortened by 7 years. This shorter life expectancy is from weight-associated effects alone. Obesity also causes many life-shortening conditions:
- Ninety percent of people who develop type 2 diabetes will have a body mass index (BMI) greater than 23.
- The risk of getting type 2 diabetes is highest if the weight is gained during childhood and there is a family history of diabetes, abdominal obesity, or mother having had gestational diabetes.
- If you have obesity, the chance of developing high blood pressure is up to five times greater compared to someone with a normal weight.
- Eighty-five percent of those diagnosed with high blood pressure have a BMI above 25.
- Increasing cholesterol levels are associated with weight increases above a BMI of as little as 21.
High cholesterol, elevated blood pressure and the presence of diabetes in turn lead to increased heart disease.
- In a study with over 300,000 people followed-up over 7 years, every unit increase in BMI led to a 9% increased risk for heart attack.
- In the same study there was an 8% increased risk of stroke.
- In women with obesity plus high blood pressure, 70% will develop an enlarged heart and 14% will get heart failure.
Breathing capacity can be affected by having obesity.
- Sleep apnea (halted breathing during sleep) is much more common in those who have obesity.
- Asthma is more common as BMI goes up.
- Collapse of lung tissues and more lung infections are more common after anesthesia for surgery in patients with obesity.
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By Dace L. Trence, MD, FACE
About the study
Research conducted at the IRCM was supported by the J.A. DeSe`ve Chair in clinical research, the Fonds de recherche du Que’bec - Sante’ (FRQS) and the Canadian Diabetes Association.
For more information, please refer to the article summary published online by The Journal of Clinical Endocrinology & Metabolism.
About Re’mi Rabasa-Lhoret
Dr. Re’mi Rabasa-Lhoret completed his doctoral degree (MD) with a specialization in endocrinology, metabolism and nutrition at the Universite’ Montpellier in France. He then obtained a PhD in food sciences, and completed a postdoctoral fellowship in physiology and molecular biology. At the IRCM, Dr. Rabasa-Lhoret is Director of the Metabolic Diseases research unit, Director of the Diabetes, Metabolism and Obesity clinic, and Director of the research platform on obesity, metabolism and diabetes. He is an associate professor in the Department of Nutrition at the Universite’ de Montre’al. He is also adjunct professor in the Department of Medicine (Division of Experimental Medicine) at McGill University. Dr. Rabasa-Lhoret is a Clinical Research Scholar from the Fonds de recherche du Que’bec - Sante’ and holds the J.A. DeSe`ve Chair in clinical research.
What are the complications of childhood obesity?
Obesity in childhood may result in serious medical problems in childhood such as
- type 2 diabetes
- high blood pressure and elevated blood cholesterol
- metabolic syndrome: a number of conditions that are all associated with high blood insulin levels including type 2 diabetes and high blood pressure
- liver disease
- bone and joint problems
- respiratory problems such as asthma
- sleep disorders such as difficulty breathing while asleep (sleep apnea)
- earlier than normal puberty or menstruation
- eating disorders such as anorexia or bulimia
- skin infections due to moisture from sweat being trapped in skin folds
- fatigue
About the IRCM
Founded in 1967, the Institut de recherches cliniques de Montre’al (http://www.ircm.qc.ca) is currently comprised of 35 research units in various fields, namely immunity and viral infections, cardiovascular and metabolic diseases, cancer and genetic diseases, neurobiology and development, systems biology and medicinal chemistry. It also houses four specialized research clinics (cholesterol, cystic fibrosis, diabetes and obesity, hypertension), eight core facilities and three research platforms with state-of-the-art equipment. The IRCM employs 425 people and is an independent institution affiliated with the Universite’ de Montre’al. The IRCM Clinic is associated to the Centre hospitalier de l’Universite’ de Montre’al (CHUM). The IRCM also maintains a long-standing association with McGill University. The IRCM is funded by the Quebec ministry of Higher Education, Research, Science and Technology.
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