Study under review: Probiotic supplementation attenuates increases in body mass and fat mass during highfat diet in healthy young adults
The human gut microbiome is a bit like an ant colony. While individual ants are extremely small, their sheer numbers and work ethic can have a profound effect on the local environment. The gut microbiome consists of up to 100 trillion bacterial cells, compared to the 37 trillion that make up the human body. While these individual bacterial cells are relatively tiny, they too can have a significant effect on their local environment.
The microbiome has attracted increasing attention over the past year, appearing in the ERD multiple times. This review details a recent study that examined how supplementation of our little gut bugs could potentially help prevent fat mass gain during excess caloric consumption.
There is a lot of evidence that suggests people with metabolic disorders, obesity, or diabetes have a different gut microbiome than healthy people. Dietary changes can also have a significant influence on the type and quantity of gut microbes.
Whether or not these associations are causal is not clear. One candidate for the causal link is endotoxin, or bacterial lipopolysaccharide (LPS, shown in Figure 1). Normally, these lipid-sugar linked molecules are found on the surface of specific strains of bacteria (gram-negative) where they contribute to numerous functions, including improving structural integrity and defending against attack. LPS is either shed while the bacteria are alive or upon their death. These molecules are then able to enter through the partially permeable digestive system and elicit a strong immune response. This response is linked to a host of maladies (at least in rodents), including, but not limited to, obesity and insulin resistance.
Since diet is able to change the gut microbiome, and there is a possible negative interaction between host and gut microbes potentially mediated through endotoxins, it comes as no surprise that diet, particularly high-fat diets, can affect circulating endotoxin concentrations. These elevated endotoxin levels could then lead to an innate immune response that results in low-grade systemic inflammation and negatively impact glucose homeostasis.
Only specific strains of bacteria are responsible for the production of endotoxins. Theoretically, shifting the gut microbiome away from these strains could ameliorate some of the negative effects attributed to endotoxins. This has been a relatively recent avenue of investigation for scientists, which has demonstrated that specific species compete with gram-negative strains. This mechanism could help explain the results of some previous reports of probiotic supplementation, which found that these probiotics can regulate weight gain.
This study examines supplementation of probiotics during a high-fat hypercaloric diet. It is different from from past studies in that it has a slightly longer duration (14 days), uses a multi-strain probiotic, and investigates weight gain in healthy individuals. Researchers also made an effort to determine the mechanism of action responsible for any health effects.
The gut microbiome changes in response to diet and is a potential factor in weight gain and insulin resistance. One player that mediates this interaction is a group of compounds found within bacteria called endotoxins, which are able to elicit a strong immune response. These endotoxins are only produced by specific bacteria. The objective of this study was to observe if probiotic supplementation aimed at changing the microbiome to produce fewer endotoxins could modulate weight gain during a hypercaloric diet.
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Other Articles in Issue #13 (November 2015)
What are you feeding your bacteria?
While probiotics get most of the press, prebiotics arguably have more potential for altering one’s microbiome. This study looks at a promising type of prebiotic supplement to see if it might impact appetite and inflammation.
Breakfast: A disempowering nutritional dogma
By Martin MacDonald, Msc
Return of the globule: milk fat strikes back
Milk fat is structurally different than most other fats, and the milk fat globule membrane has been looked at previously (twice in Study Deep Dives, in fact) for its impact on chronic disease. But could it also impact response to exercise?
Studies have shown that supplement buyers generally trust the supplements they buy. That might not be the safest assumption, as dietary supplements that are presumed helpful or neutral may sometimes cause serious side effects, as quantified by this study.
The espresso effect: caffeine and circadian rhythm
Your daily rhythms are influenced by “zeitgebers” such as light and exercise. But until now, we haven’t known the exact impact of late-day caffeine intake on melatonin and circadian rhythms.
Money, time, and the science that suits us
By David Katz, MD, MPH
Human eating patterns ... there’s an app for that
Eating throughout the day has become quite normal, given the ubiquitous availability of snack foods. Partly due to this, diet research has been plagued by inaccurate self-reports. This study used an app to get around that issue.
Does marijuana actually boost creativity?
Ancedotally, weed has been claimed as a creativity booster for decades. With THC having an effect on dopamine, a plausible mechanism exists. This randomized trial puts marijuana to the test.
Diet and autism: no gluten, no casein, no difference?
Gluten and casein are two food components often linked with autism spectrum disorder symptoms. Hence the prevalance of wheat and dairy free diets. But will they work in a rigorously controlled trial?