The world’s children are fat in record numbers.
From Kuwait to Mexico to the UK and beyond, families and health departments are struggling with costly and dangerous health problems related to overweight and obesity in children. Many young people are swallowing statins for high cholesterol and taking pills or even injecting insulin for what was once called “adult-onset diabetes.”
We all know that energy imbalance leading to obesity can be caused by rich food and insufficient activity. But a host of other factors can also lead to excess weight: stress, medications, sleep debt and microbial activity.
What we know about microbes and obesity:
Lean and obese children harbor different types of microbes. The microflora of the obese include fewer Bacteroidetes and more Firmicutes than lean people. For more background, a 2008 review article from the Mayo Clinic explores the role of gut microflora in obesity.
Gut microbes may direct fat accumulation in several enterprising ways:
- by harvesting more energy from food
- producing short chain fatty acids
- changing host genes which multiply number of fat cells
- triggering inflammation
Indeed, several different species of lactobacilli, part of the Firmicutes phyla, have been associated with one or more of the above changes
- Lactobacillus reuteri was associated with obesity.
- And infants fed with Lactobacillus rhamnosus-enriched formula grew better than those fed with regular formula.
However, lactobacilli are also linked with weight loss in published studies, unlike the above behavior:
- A strain of Lactobacillus gasseri from human breast milk was given to rats on a high-carbohydrate diet. The percent increase in body weight and fat pad mass was lower in the test group.
- In a Swedish study, another lactobacillus decreased fat storage by altering lipoprotein lipase.
- Lactobacillus plantaraum is another showing potential. In mice, it reduced fat cell size.
In a 2014 study, Frida Karlsson Videhult and colleagues at Umea University in Sweden asked whether infants fed with lactobacilli would have long-term effects in body composition, growth and other biomarkers. Read the research in the European Journal of Nutrition. Of the original 179 infants, 120 were assessed at 8-9 years of age. Results: No impact seen. As more probiotic products are introduced, long-term follow-up will be needed.
Then there are bifidobacteria, which are some of the most numerous probiotics in the gut. (They are not Bacteroidetes):
- Bifidobacterium was given to high fat diet-induced obese rats in a 2011 study. Results: reduced body and fat weights as well as other markers of a high-fat diet.
These data suggest a promising new angle for treating obesity. But when microbes can do the opposite–cause growth and weight gain, caution must be used.
Science is still figuring it all out.