Thursday, December 4, 2014

Can Gut Bugs Cause Depression?

sharma-obesity-gut-buts1Regular readers will by now be well aware of the rapidly growing body of researcher supporting the idea that your gut bugs (of which you have more than you have cells in your body) may well play a key role in determining your risk for obesity and other metabolic disorders.

Now, a paper by Ruth Ann Luna and Jane Foster from Baylor College of Medicine and McMaster University, respectively, published in Current Opinion in Biotechnology, review the evidence that gut bugs may well also have significant effects on your stress response as well as other aspects of mental healthy, including depression.

As one example, they cite a study that shows,

“…a general underrepresentation of the Bacteroidetes phylum in depressed patients and an association of the Lachnospiraceae family with the depression group, and interestingly, even with a decrease in Bacteroidetes, specific operational taxonomic units (OTUs) identified as members of the Bacteroidetes phylum correlated with depression.”

They also cite a number of studies showing that stress can affect gut bug populations and that certain gut bacteriomes are associated with a greater stress response, suggesting that the relationship between gut bugs and stressors may well be a two-way street.

The authors go on to describe a number of pathways that may link gut bugs to humoral, neural, and cellular signaling pathways to brain function.

Clearly, this appears a rich area of research that may well reveal pathways common to both neurological and metabolic issues, both of which may turn out to be amenable to dietary and probiotic interventions.

@DrSharma
London, UK

ResearchBlogging.orgLuna RA, & Foster JA (2014). Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression. Current opinion in biotechnology, 32C, 35-41 PMID: 25448230

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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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Tuesday, November 25, 2014

Obesity Myth: Success Is Measured In Pounds Lost

sharma-obesity-5as-booklet-coverFinally, in this series of common misconceptions about obesity management, discussed in our article in Canadian Family Physician, we address the notion that success in obesity management is best measured in the amount of weight loss:

“Given the importance of obesity as a public health problem, there is widespread effort to encourage people with excess weight to attempt weight loss.

However, a growing body of evidence suggests that a focus on weight loss as an indicator of success is not only ineffective at producing thinner, healthier bodies, but could also be damaging, contributing to food and body preoccupation, repeated cycles of weight loss and regain, reduced self-esteem, eating disorders, and social weight stigmatization and discrimination. 

There is also concern that “anti-fat” talk in public health campaigns might further promote weight bias and discrimination. 

Therefore, it might be time to shift the focus away from body weight to health and wellness in public health interventions.

Recently, the Canadian Obesity Network launched a tool called the 5As of Obesity Management (www.obesitynetwork.ca/5As) to guide primary care practitioners in obesity counseling and management. 

Minimal intervention strategies such as the 5 As (ask, assess, advise, agree, and assist) can guide the process of counseling a patient about behaviour change and can be implemented in busy practice settings.

Obesity management should focus on promoting healthier behaviour rather than simply reducing numbers on the scale. The 5As of Obesity Management is a practical tool to improve the success of weight management within primary care.”

@DrSharma
Edmonton, AB

 

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Monday, November 24, 2014

Obesity Myth: Anyone Can Lose Weight

scaleHere is another common misconception about obesity discussed in our article in Canadian Family Physician:

“It is common to hear that weight loss is a matter of willpower and compliance with the weight-reducing program.

However, the magnitude of weight loss is very different among individuals with the same weight-loss intervention and prescription, and the same compliance to the program—one size does not fit all.

Thus, for some people (especially those who have already lost some weight), simply putting more effort into a weight-loss program will not always result in additional weight loss given the different compensatory adaptations to weight loss.

For example, the decrease in energy expenditure that occurs during weight loss is highly variable between people and might dampen efforts to lose additional body fat.

Such compensatory mechanisms might sometimes fully counteract the 500 kcal per day decrease recommended in most dietary interventions, making it very difficult for such “poor responders” to lose weight.

Physicians should remember that obesity is not a choice and weight-loss success is different for every patient.

Success can be defined as better quality of life, greater self-esteem, higher energy levels, improved overall health, or the prevention of further weight gain.”

@DrSharma
Edmonton, AB

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Friday, November 21, 2014

Obesity Myth: Exercise is the Best Way to Lose Weight

sharma-obesity-exercise2Here is what we had to say about the role of exercise in weight management in our recent article published in Canadian Family Physician:

There is now a consistent body of evidence showing that exercise alone, despite a range of health benefits associated with regular exercise, results in rather modest weight loss (less than 2 kg on average).

One of the explanations is that exercise is often accompanied by an increase in sedentary activities and appetite and a decrease in dietary restraint that counteract the increased energy expenditure of exercise.

However, increased exercise has been shown to reduce visceral adiposity (even with minimal changes in body weight).

Individuals who include regular exercise and active living as part of a weight-loss program are more likely to improve their overall health and keep the weight off.22 This latter finding might be attributable to the effect of regular exercise on caloric intake rather than on caloric expenditure per se.

Exercise alone generally promotes modest weight loss; however, individuals who exercise regularly might improve their overall health independent of weight loss and are more likely to keep their weight off.

@DrSharma
Wellington, NZ

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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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