Do Gut Bacteria Cause Cravings?

Do you blame your own will power when it comes to holding off junk food? Perhaps you can blame it on your gut bacteria!

Many of us think that we only have one type of bacteria living in our gut which has only one role to play. In fact our bacteria outnumber our body cells 10:1* and so far there are known to be thousands of different types. This is a whole ecosystem of bacteria which is called the microbiome, one of the new buzz words in health. We are already quite familiar with the impact bacteria can have on bloating and constipation, yet scientists are discovering that this is by far not the only role they play. Like an army they are all stationed at different locations within the gut with different ‘jobs’ to do.

A recent study¹ carried out at the University College San Francisco, Arizona State University and the University of New Mexico found that the microbes are under a selective pressure to influence our eating habits in order to survive. These bacteria feed off the sugar and fat in the food we eat. They become manipulative in order to survive and some of these bacteria’s manipulations are beneficial to us and others not.

The scientists suggest that the way they do this is by giving out chemicals which travel along the vagus nerve, the main communication line between the gut and brain, and influence our habits that way. They can also influence our feeling of fullness, change taste receptors in our mouth and make us feel bad until we have eaten that particular food that bacteria needs. All of these may be contributing towards our food choices.

Incredibly, bacteria has also been found to alter our mood. French trials are looking at how the combination of two particular strains Lactobacillus acidophilus Rosell-52 and Bifidobacterium longum Rosell-175, can alter mood and have found that those participating performed better under stress when taking these two probiotic strains. This suggests that probiotics, or in this case, 'psychobiotics', could actually alter our mood could therefore become a very powerful tool in an era of anxiety, stress and low mood.

So why is it that some people may have those bacteria which stimulate cravings and others don’t? More and more research is coming out to suggest that this is all about the microbiome – the diversity of our microbiota. We need a balance of bacteria in order to be healthy. Many things can affect this negatively such as antibiotics, the amount of outdoor activity we have, and even how we were born. The BBC TV programme Horizon this week looked at how this is now also thought to be the cause of a modern epidemic of allergies such as asthma, eczema and hayfever. Kathy, also a nutritional therapist, wrote about the programme, gut bacteria and allergies, so take a look if of interest. Again, it appears to be the imbalance of the bacteria we have in our gut that can cause huge health problems.

The exciting news about all of this is that there is something we can do about it. A combination of taking probiotics and eating foods that encourage our beneficial bacteria to thrive - such as certain vegetables, could potentially give us control over our food cravings and eating habits back. This in turn could potentially have a significant impact on obesity and resulting illnesses. There is hope staving off that chocolate bar yet!

* Update January 2016 - this fact has recently been questioned. For more information read Are the bacteria cells in your body fewer than thought?

References

1. Alcock, J., Maley, C. C. and Aktipis, C. A. (2014), Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. Bioessays. doi: 10.1002/bies. 201400071