Exactly How Important is Obesity in Heart Attack and Stroke Risk?

It is well known that the risk of developing diabetes, high blood pressure, and high cholesterol is increased with overweight or obesity.  However, it's been long debated as to whether obesity itself increases the risk of heart attack and stroke (and if so, how important is this effect), or whether the risk conferred by excess body weight is strictly mediated by these risk factors.

A new study in the Lancet puts some numbers on these answers for us.  The study pooled data from 1.8 million people from almost 100 different studies globally, and they looked at what percentage of heart attack and stroke risk was attributable to blood sugar, blood pressure, cholesterol, vs overweight and obesity themselves.

They found that for every 5 kg/m2 increase in body mass index (you can calculate your own BMI here in the right hand column), the risk of heart disease went up by 27%, and the risk of stroke increased by 18%.  They found that only about half of the excess risk of heart disease with higher BMI was mediated by blood sugar, blood pressure and cholesterol, and about three quarters for the risk of stroke.

In other words, about half of the risk of heart disease, and about a quarter of the risk of stroke, appears to be mediated by excess body weight itself (and/or possibly unknown risk factors), independent of these other risk factors.

The take home messages here, as I see it, is that it is not enough to treat the blood sugar/pressure/cholesterol abnormalities in a person who carries excess body weight, nor is it enough to target weight management alone - all too often, we see these risk factors go untreated for years as individuals continue to try the lifestyle approach, unfortunately most often without success. These risk factors need to be proactively treated, in addition to a sound approach to permanent lifestyle changes that will facilitate weight management and improvement in these risk factors.

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Obesity and Hearing Loss in Women

Excuse me?  Didn't quite catch that.  Yes - it's correct that obesity and hearing loss are together in the title of this post, as it seems that obesity is an emerging risk factor for hearing impairment.

A recent study looked at over 68,000 women enrolled in the Nurses' Health Study between 1989 and 2009, and found that just over 11,000 cases of hearing impairment were reported.  They found that for women with a Body Mass Index of 40 or higher, there was a 25% increased risk of developing hearing impairment, compared to women with a BMI under 25.  A larger waist was also associated with a higher risk of hearing loss.

Interestingly, higher physical activity was associated with a lower risk of hearing impairment.

How can this be?  It is possible that in states of obesity or poorer metabolic health, some of the 'bad' or 'inflammatory' chemicals that are produced by the unhealthy metabolic fat that collects around our organs may damage the nerve cells in the ear.  In medical terms, this includes oxidative stress and the formation of reactive species.  Hardening of the arteries probably also plays a role - just like atherosclerosis manifests as narrowing of the arteries in the heart and brain, the small arterioles become hardened as well and can compromise blood supply to our hearing apparatus.

One more health concern to add to the list of possible concerns associated with carrying excess body weight.

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Hormone Treatments for Weight Loss?

In our toolbox of obesity treatments, there is very little available as far as medications go.  We know that there are many hormones involved in the the sensation of feeling full (called 'satiety'), so current research is now exploring these hormones, to see if they can ultimately be developed into obesity treatments.

My colleagues and I at the University of Copenhagen have just published one such study in the American Journal of Physiology.  We studied two hormones, GLP-1 and PYY3-36, both of which are hormones that are released when we eat, working to slow down our stomachs and tell our brains that we feel full.  We looked at intravenous infusions of these hormones, to try to understand how they may work together, and how they may affect a person's desire to eat when given in combination.

We found that when GLP-1 and PYY3-36 were given together, the inhibitory effect on food intake was synergistic - ie, more than then sum of each hormone individually.  We found that these hormones together elicited a decrease in a hunger hormone called ghrelin, as well as a slight increase in nausea (due to the stomach slowing effect), but in further analyses, we found that neither of these factors was responsible for the lower amount of food that participants elected to eat after the infusions were complete.

So, this study shows us that these two hormones in combination work together in some way to give us a sense of satiety or fullness, but exactly how they work together is not clear.  One small step forward in the big picture of understanding the complex web of hunger and fullness!

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A Different Kind of STAMPEDE

Obesity (bariatric) surgery has become accepted as an option for the treatment of type 2 diabetes by most diabetes guidelines around the world. The data on which these recommendations are based are from shorter studies, from weeks to months to up to 2 years. 

Now, in a landmark randomized controlled trial published in the New England Journal of Medicine, 3 year data shows us that the benefit of bariatric surgery to diabetes control is sustained out to at least 3 years.

The study, called the STAMPEDE study, randomized 150 people with type 2 diabetes, to receive either intensive medical treatment of diabetes alone (with a goal A1C of 6.0%), vs medical treatment plus gastric bypass surgery, vs medical treatment plus sleeve gastrectomy.

The study clearly shows that gastric bypass surgery and sleeve gastrectomy are superior to intensive medical therapy alone, to have control of type 2 diabetes at 3 years. Thirty-eight percent of patients who had gastric bypass surgery had tight control at 3 years, compared to 24% after sleeve gastrectomy, compared to only 5% receiving medical treatment alone. (The difference between the gastric bypass and sleeve groups was not statistically significant.)

With the above being said, I do take issue to how this study was structured, in that the goals for control of diabetes were too tight. We no longer recommend an A1C of 6.0% as a goal, as another landmark study (the ACCORD study) showed that control this tight was associated with an increased risk of death. It would be interesting to know how the numbers would have panned out if the commonly accepted A1C target of 7.0% was used instead.

However, the point of the article remains that gastric bypass and sleeve gastrectomy results in control of type 2 diabetes in significantly more patients than medical treatment alone. There is no doubt that Bariatric surgery is an important tool in our toolbox of diabetes therapy in the 21st century.

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Landmark Study Shows Physical Activity Decreases Heart Attack Risk

We have all heard before that physical activity is important for overall health.  Believe it or not, it is now for the first time that we have solid evidence to prove that being more active in daily life decreases the risk of cardiovascular events (eg heart attacks) in particular.

The study, recently published in Lancet, assessed pedometer data (recording # steps per day) in over 9,000 people with prediabetes from 40 countries around the world.  They examined how many steps per day each person took at the beginning of the study and again at 1 year, and then followed them up for an additional 6 years.  They found that:

• people who were more active at baseline (start of the study) had a lower risk of cardiovascular events
• people who became more active over the course of a year had a lower risk of cardiovascular events at 6 years
• for every 2,000 steps/day increase in activity over a year (about one mile or 1.6 km), there was an 8% decrease in cardiovascular events!

Prior to this study, the studies suggesting that being more active decreases the risk of cardiovascular events have been based on less rigorous data and study design.  Also, previous studies have generally been based on self reported data (ie the person in the study gauges how active they are), whereas this study objectively measured number of steps per day with pedometers.  For these reasons, this study is considered a landmark trial in that it has shown us, very objectively and in a high quality study design, that being active really does decrease heart risk in a group of high risk individuals.

See if you can find ways to take more steps in your day!

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The Low Down on Electronic Cigarettes

For many Canadians (and Canadian doctors), e-cigarettes are an enigma wrapped in a mystery.  Though they are not regulated or approved for sale in Canada, they seem to be finding their way across the border in increasing quantities.  The Canadian Medical Association Journal published a couple of great articles about them in a recent issue to teach Canadian doctors what e-cigarettes are all about.   Here are some key points:


1.  What are e-cigarettes?

They are canisters shaped like cigarettes, which release vapor containing flavoring agents, other chemicals, and sometimes nicotine.  They are intended to simulate smoking without exposure to as many chemicals as tobacco.


2.  Are e-cigarettes safer than smoking regular cigarettes?

Hard to say.  Some studies show that e-cigarettes contain some impurities and carcinogens; also, the ones that contain nicotine still promote the nicotine dependence that keeps people addicted to smoking.  Even worse, smoking e-cigarettes could induce an addiction in someone who was previously a nonsmoker.

3.  Are e-cigarettes useful to help someone stop smoking?

Again, hard to say, as they have not been well studied. One randomized controlled clinical trial was not able to show superiority compared to nicotine patches. Contrast this with several other medication and behavioral approaches to smoking cessation which have been proven effective in clinical trials (the list is available here).  Also, I would add to this discussion that stopping the physical behavior of smoking is an important component of stopping smoking as a habit - in other words, the action of e-smoking may be too close to actual smoking to actually help a person to break the behavior.


A concern in the US is that e-cigarette companies are free to tempt American youth with fruit flavored e-cigarettes and celebrity endorsements, effectively resurrecting marketing campaigns that the tobacco industry used to use.  Thus, there is a fear that the e-cigarette industry could lure young people (or anyone for that matter) into nicotine addiction and possibly subsequent tobacco use.

So, while e-cigarettes may seem like a good idea on the surface, they have a dark side: those that contain nicotine propagate the addiction and may not effectively help people quit smoking; and even worse, they may lure non smokers into the dangerous world of smoking addiction.

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Could Cinnamon Be....Dangerous?

Cinnamon first came to my attention over a decade ago, when a randomized clinical trial was published suggesting that cinnamon improved blood sugars and cholesterol levels in people with type 2 diabetes.  Another randomized controlled trial confirmed the improvement in blood glucose as well.  However, the quantities used were quite large, up to 6 grams per day - imagine dumping that amount of powder on your cereal in the morning?!  Ick.

It turns out that taking in generous quantities of cinnamon may in fact be harmful - depending on what kind of cinnamon you consume.  The most common type of cinnamon sold is cassia cinnamon, which contains a natural but toxic component called coumarin, which has been associated with possible liver toxicity. This is contrasted with ceylon cinnamon, which is thought to contain little coumarin.

It actually doesn't take that much cinnamon to exceed the daily tolerable intake of coumarin - as little as a teaspoon (which is just under 3 grams) of cassia cinnamon per day may be too much.

This has lead to an outrage and heartbreak in Denmark, where the cinnamon bun or kanelsnegle (a staple Danish bakery product) has come under attack following the EU's recent moves to limit cinnamon consumption due to the risks noted above.

So, cinnamon is not a great treatment for patients with diabetes - cassia cinnamon must not be taken in the quantities needed to have an impact on blood sugars due to possible toxicity, and eating that amount of ceylon cinnamon every day just isn't practical.

Follow me on twitter: @drsuepedersen

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