Gut Bacteria to Treat Obesity?
By: Gunnar De Winter
Tags: Health, Biology, Science, Disease, Obesity

Gut Bacteria to Treat Obesity?

(Pixabay, geralt)

You and your microbes

You are your microbes. That is an exaggeration, but ever since we have the research tools to spy on our microbiomes, we see their tiny fingerprints everywhere.

From how we metabolize food and how hungry we get to our risk for diseases such as Alzheimer’s, the microbial residents in our gut (the ‘gut microbiome’) appear to be at least correlatively involved.

(Wikimedia commons, Rcragun)

Of course, it is not always easy to separate correlation (things that occur together) from causation (one thig causes another).

In microbiome research too, we need to be aware of factors that affect both the microbiome and the trait we’re interested in (these factors are called confounders)

Still, our personality traits, our risk for cancer, and the effectiveness of chemotherapy all appear to be correlated with specific microbiome compositions. The gut microbiome’s reach can even span generations since the maternal microbiome can affect the brain development of children in the womb.

Both the number and diversity of gut microbe species is important, with functional diversity being a major factor. So, it’s not necessarily the species of bacteria that matters most, but what it does, its ‘function’. This is because many of the effects of gut microbes are mediated through the chemicals they produce.

From mice to humans

(Pixabay, Etouale)

If you care to dig a little, you’ll soon find out that a lot of headline-making healthcare research was performed on mice.

These findings can be good indications of things that may or may not work, it’s no guarantee that whatever breakthrough was achieved will work in human beings as well.

In microbiome research, a lot of observational research is actually done in humans. Interventional research — where we purposefully try to change something — is skewed more to the lab animal side.

A specific type of interventional research in gut microbiome studies involves changing the gut microbiome. There are a few ways to achieve this: changing diet, lifestyle, or environment, introducing specific strains of bacteria, or fecal microbiota transplants (FMT). Poop exchanges, in other words. Such FMTs are currently being used (in humans) for Clostridium difficile infection, and similar therapies are being investigated for various gastrointestinal and neurological conditions.

Obese and lean microbiomes

We know that certain microbiome compositions correlate with obesity. We also know that specific strains of probiotic bacteria can affect ghrelin signaling (the ‘hunger hormone’).

So… are there probiotics we can use to help obese people (who choose to) slim down?

A new study tried to find out.

What’s interesting about the study (and the reason I wrote the mice tangent above) is that they tested it simultaneously in mice and humans.

The bacterial strain in question was Bifidobacterium longum APC1472, known to affect ghrelin levels, and it was administered via drinking water. (Let’s face it, more palatable than a poop exchange.)

What happened?

In obese mice:

…decreased bodyweight, [decreased] fat depots accumulation and increased glucose tolerance.

Slimming down, losing fat, and better glucose tolerance. Success across the board.

In obese humans:

…supplementation of B. longum APC1472 strain did not change primary outcomes of BMI or W/H ratio… reduced fasting glucose, cortisol awakening responses and increased active ghrelin.

No weight loss, no fat loss, but better glucose tolerance and possibly less hunger pangs (active ghrelin means circulating ghrelin, or ghrelin not doing its hunger-promoting thing: active ghrelin levels are lower in obese people).

You know where I’m going with this…

Mice are not humans! In mice, this B. longum strain effectively modulated body weight and body fat percentage. In humans, it did not.

The researchers conclude:

B. longum APC1472 has promising potential to be developed as a valuable supplement in reducing specific markers of obesity and is poised to have significant relevance in conditions of heightened blood glucose, such as type 2 diabetes.

Yes, reducing markers of obesity (and definitely potential for diabetes)

No, not a magic probiotic pill that keeps you lean.