All posts for the month December, 2014

Hello readers: today’s article is about how your lungs and your gut seem to interact: changes in gut microflora can affect lung activity, and vice versa. It is entitled, “Changes in the Bacterial Microbiota in Gut, Blood, and Lungs Following Acute LPS Instillation into Mice Lungs”. LPS is short for lipopolysaccharide, which is a component of the surface of some bacteria.

Here they were looking at total bacterial counts in blood and in the cecum (a region of the gut), as well as the microbiome composition present in lung fluid, blood, and the cecum. They found that adding LPS (it’s not clear what species the LPS is from, or if it is from a mixture of species) changed total bacterial counts in the cecum as well as the blood, and that adding antibiotics could reduce the changes seen in blood.

This evidence supports prior work indicating that, bacteria may translocate from the gut to the blood (where perhaps they interact with lung tissue) and indicates that the lungs- much like the gut- contain a large and diverse population of bacteria. More work is needed to characterize this environment and determine relationships between lung bacteria and lung dysfunction. The link to gut bacteria is also interesting- could this be why there are websites recommending different foods for helping people with asthma? Studies are inconclusive, but that may be expected if people weren’t taking the starting gut community into account when designing studies intended to determine if diet changes help asthma. A link between diet, your gut microbes, your lung microbes, and your breathing suggests all kinds of new ways to help treat asthma, and possibly other lung problems as well.

Hello, readers! Today’s interesting paper, which outlines evidence supporting the hypothesis that the composition of the bacteria in your gut will influence your eating behaviour, comes from Alcock et al. and was published earlier this year. The article is entitled, “Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms” and is found here.

To summarize this article, it’s thought that there may be several ways in which the composition of your gut bacteria might affect eating behaviour, and by doing so, affect phenomena like metabolic disorders, heart disease, or cancer. Some key points are listed below:

1. There is a selective influence of diet on the composition of gut bacteria: different bacteria eat or thrive on different nutrients, so what you eat will affect the composition of bacteria in your gut.

2. Microbes can manipulate host behaviour: This section outlines some studies which indicate that food cravings and mood are associated with differences in gut microflora. For example: a study in which chocolate cravings are associated with a changed gut bacterial composition can be found here. Additional evidence indicating that negative mood, or psychological shifts (e.g. “gut-brain axis”- related changes) can be associated with particular gut bacterial composition is given in this section. This might make sense if feeling anxious or unhappy leads to eating certain foods.  The authors suggest that by changing host psychology, gut microbes affect eating patterns.

3. Microbes modulate host receptor expression: Might gut bacteria alter host eating preferences by changing taste receptors in the host, which would make food taste different?

4. Microbes can influence hosts through hormones and effects on weight: Microbes can produce compounds which are similar in structure to mammalian hormones- and by so doing, can directly affect mood and behaviour, and probably directly affect physiological changes as well. There are studies describing links between metabolic disorders such as obesity with changes in gut bacterial communities, and other studies linking probiotics with changes in weight and weight-related phenomena. 

Further work on links between gut bacteria and eating habits may help us figure out how to make it easier for people to choose and maintain a healthy diet.