Thursday, July 17, 2014

Infant Antibiotic Exposure and Obesity Risk

sharma-obesity-gut-buts1With all the interest in the role of the gut bacteriome in the development of obesity, it was only a matter of time before someone examined the relationship between antibiotic use and obesity risk.

This is exactly what Anita Kozyrskyj and colleagues from the University of Alberta, Edmonton, Canada, explored in a paper now published in the International Journal of Obesity.

For their study they linked rovincial healthcare records to clinical and survey data from a Canadian longitudinal birth cohort study, whereby antibiotic exposure during the first year of life was documented from prescription records.

Overweight and central adiposity were determined from anthropometric measurements at ages 9 (n=616) and 12 (n=431) years.

According to this analysis, infants receiving antibiotics in the first year of life were about twice as likely to be overweight later in childhood compared to those who were unexposed.

However, after adjustment for birth weight, breastfeeding, maternal overweight and other potential confounders, this association persisted in boys but not in girls. The reason for this discrepancy is not clear.

Although these findings are in line with the notion that early use of antibiotics may predispose to obesity, it is important to not that these type of studies cannot prove causality.

It may well be that other non-measured factors could explain this association (e.g. overprotective or lower SES parents may be more likely to use antibiotics in their infants – both factors are independently associated with higher rates of obesity).

Nevertheless, given the rather high rates of antibiotic exposure in infants it appears that this may well be a promising area for further research not just in the context of obesity but also for many of the other conditions that are now believed to be influenced by intestinal flora.

@DrSharma
Edmonton, AB

ResearchBlogging.orgAzad MB, Bridgman SL, Becker AB, & Kozyrskyj AL (2014). Infant antibiotic exposure and the development of childhood overweight and central adiposity. International journal of obesity (2005) PMID: 25012772

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Monday, June 2, 2014

There Has Not Been A Single Success Story in National Obesity Prevention in The Past 33 Years

sharma-obesity_global_obesity_mapJust back from the 21st European Congress on Obesity, I missed out on 100s of media interviews I could have done last week as the media were abuzz with the latest obesity statistics from around the world.

In what will clearly be considered a “landmark” paper by ~150 authors published in The Lancet, we now have the latest summary of global, regional and national data on obesity.

Based on the analyses of almost 1800 surveys, reports, and published studies, the worldwide prevalence of adults with a body-mass index (BMI) of 25 kg/m2 or greater increased between 1980 and 2013 from 29 6o 37% in men and from 30 to 38% in women.

In 2013, 23% of children and adolescents in developed countries were overweight or obese while the same is true for about ~12% of kids in developing countries.

Together, this leave about 2.1 billion of the world populations as currently overweight or obese with numbers growing in virtually every region of the world (albeit with a bit of a slow down in developed countries).

Thus, the authors conclude that,

Not only is obesity increasing, but no national success stories have been reported in the past 33 years.

Obviously, there are many reasons why we lack success stories.

No doubt, one could point to governments that have not tried hard enough, or the food and leisure industry that sustains its overwhelming influence on consumer “choices”, or the continuing “westernization” of global lifestyles.

No doubt, many policies have been tried (e.g. fat taxes, menu labelling, school food programs, fitness taxes, BMI report cards as well as more drastic “shame and blame” tactics) but conclusive evidence that any such measures are working to reverse the tide remains elusive.

It may well be that the flattening of obesity (but not severe obesity) rates in developed countries may have more to do with the “natural” history of this epidemic, than with any public health measures.

On the other hand, perhaps the reason so little progress has been made in preventing obesity is that we are not going after the right targets, namely to change the actual life experiences of overworked, sleep deprived, stress-out families living in a culture of “grabbing a bite” and “working lunches” at one end and the millions living with poor education and food insecurity at the other. No amount of fiddling with menu labelling is about to change that.

What is sad in all of this is the simple fact that virtually no government has yet developed a comprehensive plan on how to improve access to obesity treatments for its populations. Rather, overweight and obese people the world over continue to be denied medical care for this disease on the simple basis that it is their own “fault”.

So while the world awaits the wonder of “prevention” to hopefully one day work its magic, millions of people around the world continue struggling on their own with no help in sight.

Let me guess what will happen as a result of these new numbers – not much!

@DrSharma
Edmonton, Alberta

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Tuesday, May 27, 2014

What’s Europe Doing About Obesity?

ECO2014 logoAs I head out to attend the 21st European Congress on Obesity in Sophia, Bulgaria, I came across this interactive site that allows interested readers to checkout obesity interventions across Europe.

The atlas of European projects and interventions for obesity prevention in adults is part of the SPOTLIGHT project which udertook a Europe-wide survey to provide an overview of projects and interventions to prevent adult obesity through improving diet and physical activity.

While the atlas may not include every single intervention that is currently happening, it does provide a sense of the scope and range of these activities.

For each project or intervention the atlas considers the Reach, Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) aspects and presents these data where available.

I am sure I will have plenty more to report on based on what I hear at the conference.

@DrSharma
Munich, Germany

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Monday, May 26, 2014

Does Short-Term Weight Loss Reduce Cardiovascular Risk?

sharma-obesity-weight-gainIf you believe recent media headlines describing the findings of a paper published in The Lancet last week, you may be convinced that any weight loss – even if you don’t keep the weight off – reduces your risk for cardiovascular disease.

The study, reports on the relationship between lifelong patterns of BMI and cardiovascular risk a 60-64 year-old British  birth cohort born in 1946.

Participants were classified as normal weight or overweight or obese based on heights and weights measured during childhood (at ages 2, 4, 6, 7, and 11 years) and adulthood (at ages 36, 43, 53 and 60–64 years).

As may be expected, various measures of cardiovascular and metabolic risk factors were positively related to extent and duration of adiposity.

There were, however, two findings that may seem rather unexpected:

Firstly, adiposity in childhood did not seem to matter as a predictor of CV risk in adulthood.

Secondly, it appeared that individuals who dropped at least one BMI category at any time during adulthood, irrespective of whether or not this weight loss was maintained, had lower cardiovascular (but not diabetes) risk than did those who never lost weight.

From these findings the authors conclude that,

…cardiovascular benefit might arise from weight loss in adulthood, irrespective of when this weight loss is achieved, and support public health policies for lifestyle modifications for prevention and management of overweight and obese individuals at all ages.

While it is easy to see why sustaining weight-loss as an adult (particularly if you have risk factors for cardiovascular disease) may well be beneficial, it is hard to imagine a plausible biological pathway that would link a “short-term” weight loss to long-term improvements in cardiovascular risk.

Indeed, the authors provide no explanation for their findings. They also provide no further information on the people who lost weight compared to the people who did not.

My first response would be to look for biological plausible confounders – were people who lost weight at anytime as adults perhaps more conscious or concerned about their health than those who did not? Or, were they more metabolically healthy to start with?

Let us also not forget that this was merely an observational study – association does not prove causality.

This is not to say that the findings are entirely implausible. There is some literature on the long-term “legacy effect” of lifestyle interventions on metabolic risk factors – but the biological basis for this is unknown and some colleagues doubt wether this effect really exists.

Given that weight regain is rather common after weight loss, it will be interesting to see if other studies can demonstrate lasting benefits of short-term weight loss.

At this time some scepticism may well be warranted.

@DrSharma
Edmonton, AB

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Tuesday, May 20, 2014

Mountain Living Reduces Obesity?

mountain pineLiving not too far from the Canadian Rockies, you cannot help but notice how vegetation gets short and stunted at higher elevations.

The same is apparently true for humans – while moving to higher altitudes may not make your shorter, it certainly appears to reduce your body fat and perhaps risk of obesity.

Indeed, there is ample evidence from both animal and human studies demonstrating that hypobaric hypoxia (lower oxygen levels combined with lower athmospheric pressure) may have a profound affect on body composition.

Now, a large epidemiological study by Jameson Voss and colleagues, published in PLOS|One provides strong evidence to support this hypothesis.

The researchers looked at all outpatient medical encounters for overweight active component enlisted service members in the U.S. Army or Air Force from January 2006 to December 2012 stationed in the United States and compared obesity related ICD-9 codes between those stationed at high altitudes (>1.96 kilometers above sea level) with those at low altitudes (<0.98 kilometers).

It turns out that service members stationed at higher altitudes were about 40% less likely to become obese than those stationed at lower altitudes.

Although one must always be careful to infer causality from epidemiological evidence, these findings are certainly in line with the experimental evidence on hypobaric hypoxia.

In light of these findings, I can already see the next opportunity for commercial weight loss – hypobaric hypoxic chambers at your local tan studio.

@DrSharma
Edmonton, AB

ResearchBlogging.orgVoss JD, Allison DB, Webber BJ, Otto JL, & Clark LL (2014). Lower Obesity Rate during Residence at High Altitude among a Military Population with Frequent Migration: A Quasi Experimental Model for Investigating Spatial Causation. PloS one, 9 (4) PMID: 24740173

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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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