Tuesday, December 2, 2014

Does Maternal Obesity Affect the Gut Microbiome of the Offspring?

sharma-obesity-gut-buts1Yesterday, I blogged about the Maternal Resource Hypothesis, proposed by Edward Archer, as a driver of childhood obesity.

Today’s post is about another interesting finding by Jeffrey Galley and colleagues from Ohio State University, published in PLOS one, suggesting that maternal obesity may be associated with differences in the gut microbiome in children in early life.

The researchers compared the gut bugs from fecal samples from children 18–27 months of age (n = 77) born to obese or non-obese mothers.

At least in women of higher socioeconomic status, offspring of obese mothers showed significant differences in their gut bacteriome from those of non-obese mothers in a manner that has been previously linked to differences in weight and diet (differences were noted in the abundances of Faecalibacterium spp., Eubacterium spp., Oscillibacter spp., and Blautia spp).

While these findings were limited to women of higher socioeconomic status, the authors do not have a ready explanation for these findings.

Their best guess is that perhaps the etiology of obesity may differ between women of higher and lower socioeconomic status and it may well be that the extent to which maternal obesity confers measureable changes to the gut microbiome of offspring may differ based on the etiology of maternal obesity.

It is unlikely that dietary differences explain these findings:

“In our sample, we found no differences in the children from obese and non-obese mothers in terms of breastfeeding behavior, age at which solid foods were introduced, or the current frequency of consumption of meat, vegetables, and cereals/grains regardless of maternal SES. This suggests that diet did not explain the observed differences in the children’s gut microbiome related to maternal obesity and SES.”

Indeed, the authors are quick to point out that further research is needed to better understand the relevance of the observed differences in gut microbiome composition for weight trajectory over the life course of the offspring:

The potential role of the gut microbiome in this intergenerational transmission of obesity risk warrants further attention. In particular, the stability of such effects into later childhood and adolescence, the clinical relevance of abundances of specific bacteria in conferring risk for obesity, and the ultimate impact of early life microbial profiles on long-term weight trajectory remains to be explicated.”

Nevertheless, these findings are intriguing in that they suggest a link between maternal obesity and the possible transmission of obesogenic microbes to their offspring.

@DrSharma
Vancouver, BC

ResearchBlogging.orgGalley JD, Bailey M, Kamp Dush C, Schoppe-Sullivan S, & Christian LM (2014). Maternal obesity is associated with alterations in the gut microbiome in toddlers. PloS one, 9 (11) PMID: 25409177

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Monday, December 1, 2014

Are Sedentary Moms Promoting Childhood Obesity?

Edward Archer, PhD, University of Alabama Birmingham

Edward Archer, PhD, University of Alabama Birmingham

Last week, Edward Archer from the University of Alabama at Birmingham (UAB), published a paper in the Mayo Clinic Proceedings (to much media fanfare), suggesting that the primary driver of childhood obesity is the shifting of nutrient energy to fetal adipose tissue as a result of increased maternal energy availability paired with decreased maternal energy expenditure, resulting in fetal pancreatic b-cell and adipocyte hyperplasia – a theory, which Edwards labels the “maternal resource hypothesis”.

The primary process for these changes, as readers of these pages will have read before, is through epigenetic modification of DNA, which, together with other non-genetic modes of transmission including learned behaviours and environmental exposures (socioenvironmental evolution), leads to “phenotypic evolution”, which Edward describes as,

“…a unidirectional, progressive alteration in ontogeny that is propagated over multiple successive generations and may be quantified as the change over time in the population mean for the trait under examination (eg, height and obesity).”

Since the beginning of the 20th century, socioevironmental factors have significantly altered the energy balance equation for humans

“Socioenvironmental evolution has altered the evolution of human energy metabolism by inducing substantial decrements in EE imposed by daily life while improving both the quality and the quantity of nutrient-energy availability.”

“For example, as thermoneutral environments became ubiquitous, the energy cost of thermoregulation declined, and improved sanitation (eg, clean water and safer food) and vaccinations decreased the energy cost of supporting parasites (eg, fleas) and resisting pathogens (eg, communicable diseases and diarrheal infections).”

Over the past century, these developments have led to profound phenotypic changes including,

“progressive and cumulative increases in height, body stature and mass, birthweight, organ mass, head circumference, fat mass/adiposity as well as decreases in the age at which adolescents attain sexual maturity…”

Archer goes on to describe some of the many factors that may have changed in the past century, whereby, he singles out sedentariness as one of the key drivers of these developments (not surprising given Archer’s background in exercise science).

Thus, although one could perhaps make very similar arguments for any number of factor that may have changed in the past century to, in turn, affect insulin resistance and ultimately energy partitioning (change in diet, sleep deprivation, increasing maternal age, endocrine disruptors, antibiotic use, gut microbiota, medication use and many other factors I ca think of), Archer chooses to elevate sedentariness to being the main culprit.

While this may or may not be the full story, it does not change the thrust of the paper, which implies that we need to look for the key drivers of childhood obesity in the changes to the maternal-fetal (and early childhood) environment that have put us on this self-perpetuating unidirectional cycle of phenotypic evolution.

Ergo, the solution lies in focussing on the health behaviours (again, Archer emphasizes the role of physical activity) of moms.

While Archer largely focusses on maternal transmission, we should perhaps not forget that there is now some also evidence implicating a role for epigenetic modification and intergenerational transmission through paternal DNA – yes, dads are getting older and more sedentary too (not to mention fatter).

I do however agree with Edward, that this line of thinking may well have important implications for how we approach this epidemic.

For one,

“…the acknowledgment that obesity is the result of non-genetic evolutionary forces and not gluttony and sloth may help to alter the moralizing and demoralizing social and scientific discourse that pervades both public and clinical settings.”

Secondly,

“Future research may be most productive if funding is directed away from naive examinations of energy balance per se and redirected to investigations of interventions that alter the competitive strategies of various tissues.”

Thirdly,

“From the standpoint of the clinician, accurate patient phenotyping (inclusive of family obstetric history and metabolic profiling) may allow the targeting of women most likely to be a part of populations that have evolved beyond the metabolic tipping point and therefore require significant preconception intervention.”

While none of this may be easier or more feasible than other current efforts, they may well point us in a different direction than conventional theories about what is driving childhood obesity.

@DrSharma
Calgary, AB

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Thursday, November 27, 2014

Would You Like Some Guilt With That Popcorn?

popcornYesterday, I blogged about the McKinsey discussion paper that calls on governments to throw everything they’ve got at the obesity epidemic – proven or unproven – anything is better than nothing.

That said, it is indeed timely that this week, the US-FDA announced sweeping regulations on putting calories on menus, not just in fastfood restaurants but also in grocery stores, vending machines, and movie theatres.

Personally, I am all for it – never mind that we have yet to show that providing this information at the point of purchase actually changes behaviour of the target population (namely the people who do need to watch their calories) – I, for one, do find this information helpful.

Thus, every time I visit a McDonalds restaurant (yes, I do), I study the nutritional information that this restaurant chain has been making available to any customer who bothers to ask for decades.

Indeed, I do admit to deriving a kind of voyeuristic pleasure in seeing those astonishingly high numbers on certain food items and cannot help myself from inwardly shaking my head at the poor schmucks who order those foods.

What I do wonder, however, is whether knowing these numbers has ever actually changed my own behaviour.

Take movie popcorn for instance – I love it! (interestingly this is a habit that I only developed since moving to Canada).

Not that I am not aware that a large popcorn can easily have all the calories I need for the rest of the weekend – yup, I know that – indeed, I am making an “informed choice”.

In the few milliseconds I spend thinking about whether or not I may wish to skip the popcorn this time, those calorie numbers do regularly flash through my mind – in the end, the popcorn always wins.

So how will having the numbers up on the menu board staring in my face change things for me?

My guess is that I’ll still buy the popcorn, except now it will come with an even larger portion of guilt than before.

Obviously, with the numbers up there for everyone to see (including the people in line behind me), there may well now be an added tinge of embarrassment on top of the guilt.

Well, I may not be the typical consumer or even the target of these measures – after all these are meant for the people who could obviously do with some nudging towards eating a healthier diet (not really sure why I am excluding myself from this list).

Yet, I don’t mind these measures, I have always considered this a good idea.

But will having these numbers staring me in the face everytime I eat out change my consumption of popcorn? Probably not.

Will they make me think thrice (I already think twice)? Perhaps.

So to sum up, funnily enough, I find myself in full support of this measure – even if I am not really sure why.

I guess anything is better than nothing.

@DrSharma
Frankfurt, Germany

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Wednesday, November 26, 2014

McKinsey on Obesity: Doing Something Beats Doing Nothing

McKinsey Overcoming ObesityLast week the McKinsey Global Institute, with much media fanfare, released a 120 page discussion paper titled, “Overcoming obesity: An initial economic analysis“, which estimates that the economic cost of the global obesity epidemic is upwards of $2 trillion, a number similar to the economic cost of tobacco consumption or armed conflicts.

The report identifies 74 interventions in 18 areas (ranging from policy and population health to health care) deemed to be cost effective, which, if implemented, could lead to annual savings of $1.2 billion in the UK National Health Services alone.

However, when it comes to the actual impact of these 74 strategies, the report is far more sobering in that it notes that many of these interventions are far from proven:

“The evidence base on the clinical and behavioral interventions to reduce obesity is far from complete, and ongoing investment in research is imperative. However, in many cases this is proving a barrier to action. It need not be so. We should experiment with solutions and try them out rather than waiting for perfect proof of what works, especially in the many areas where interventions are low risk. We have enough knowledge to be taking more action than we currently are.”

In other words, let’s not wait to find out what works – let’s just do something – anything (and keep our fingers crossed).

Thus, the report urges us to

“(1) deploy as many interventions as possible at scale and delivered effectively by the full range of sectors in society; (2) understand how to align incentives and build cooperation; and (3) do not focus unduly on prioritizing interventions because this can hamper constructive action.”

I can see why politicians would welcome these recommendations, as they are essentially a carte blanche to either doing nothing (we don’t have the evidence) or doing whatever they want (anything is better than nothing).

The fact that,

“Based on existing evidence, any single intervention is likely to have only a small overall impact on its own. A systemic, sustained portfolio of initiatives, delivered at scale, is needed to address the health burden.”

means that when any measure fails, it is not because it was the wrong measure but because there was either not enough of it or it was not complemented by additional measures.

Again, a free pass for politicians, who can pass whatever measures they want (based on their political ideologies or populistic pressure from their constituencies), without having to demonstrate that what they did, had any effect at all.

Of course, no report on obesity would be complete without also stressing the importance of “personal responsibility”, as if this was somehow more important for obesity than it is for diabetes, lung disease, heart disease, or any other disease I can think of.

Unfortunately, the report also includes rather nonsensical statements like,

“44 interventions bring 20% of overweight/obese Britons back to normal weight”

a sentence that defies the very chronic nature of obesity, where once established excess weight is vigorously “defended” by complex neuroendocrine responses that will counteract any change in energy balance to sustain excess body weight.

Thus, unfortunately, the authors fall into the common misconception about obesity simply being a matter of calories in and calories out, a balance that can be volitionally adjusted to achieve whatever body weight you wish to have.

Indeed, there is very little discussion in this “discussion paper” of the underlying biology of obesity, although it is acknowledged in passing:

“Even though there are important outstanding questions about diet composition, gut microbiome, and epigenetics, we are not walking blind with no sense of what to address. However, interventions to increase physical activity, reduce energy consumption, and address diet composition cannot just seek to reverse the historical trends that have left the population where it is today. For example, we cannot, nor would we wish to, reverse the invention of the Internet or the industrialization of agriculture. We need to assess what interventions make sense and are feasible in 2014.”

Will this report move governments to action? Or, even more importantly, will this report bring us any closer to reversing the epidemic or providing better treatments to people who already have obesity?

Readers may appreciate that I am not holding my breath quite yet.

ƒƒ@DrSharma
Edmonton, AB
ƒƒ

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Friday, October 24, 2014

Social Network Analysis of the Obesity Research Boot Camp

bootcamp_pin_finalRegular readers may recall that for the past nine years, I have had the privilege and pleasure of serving as faculty of the Canadian Obesity Network’s annual Obesity Research Summer Bootcamp.

The camp is open to a select group of graduate and post-graduate trainees from a wide range of disciplines with an interest in obesity research. Over nine days, the trainees are mentored and have a chance to learn about obesity research in areas ranging from basic science to epidemiology and childhood obesity to health policy.

Now, a formal network analysis of bootcamp attendees, published by Jenny Godley and colleagues in the Journal of Interdisciplinary Healthcare, documents the substantial impact that this camp has on the careers of the trainees.

As the analysis of trainees who attended this camp over its first 5 years of operation (2006-2010) shows, camp attendance had a profound positive impact on their career development, particularly in terms of establishing contacts and professional relationships.

Thus, both the quantitative and the qualitative results demonstrate the importance of interdisciplinary training and relationships for career development in obesity researcher (and possibly beyond).

Personally, participation at this camp has been one of the most rewarding experiences of my career and I look forward to continuing this annual exercise for years to come.

To apply for the 2015 Bootcamp, which is also open to international trainees – click here.

@DrSharma
Toronto, ON

ResearchBlogging.orgGodley J, Glenn NM, Sharma AM, & Spence JC (2014). Networks of trainees: examining the effects of attending an interdisciplinary research training camp on the careers of new obesity scholars. Journal of multidisciplinary healthcare, 7, 459-70 PMID: 25336965

 

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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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