Do probiotics work? Research from 2018 suggests that some probiotic strains might struggle to find a home in our gut, being quickly forced out by the established microbes.
Do probiotics work?
Research into the human microbiome is demonstrating that gut health is both complex and nuanced. Complex because of the sheer quality and quantity of microbes that we humans host. For example according to the Human Genome Project each of us has around 22,500 human genes, however it’s estimated that we also carry 100 times that number in microbial genes! Understanding the colonies of microbes (predominantly bacteria) inside our gut is further complicated because no two people have exactly the same gut flora. So therefore each of us has a unique bacterial ecosystem.
A research paper published in the journal Cell in September 2018 and highlighted by the BBC website, has made the claim that “Humans feature a person-specific gut mucosal colonization resistance to probiotics”. The study found that an 11-strain probiotic mix, administered for a month had almost no impact on the long term gut health of 25 participants. Either passing straight through the digestive tract or lingering for a short time before being forced out by the well established resident bacteria. Although provisional, the results are highly suggestive that the gut has a defence mechanism designed to protect itself from rapid colonization by new visitors. This is kind of intuitive, if any new bacteria that we ingested could quickly establish a foothold in our body then we would be much more vulnerable to harmful microbes.
Although this initial study hasn’t been replicated and is based on a relatively small number of people it suggests that probiotics might work best if they are tailored to each of us individually. That probiotics might offer the greatest benefit if they are designed to coexist with our unique resident populations. From a consumer’s point of view I am left thinking how might I be able to tell if the probiotics I consume are having a lasting effect without going down the road of expensive lab based testing? Hopefully further studies offering greater insight will follow.
People suffering from migraines tend to have particular profile of bacteria linked to nitrate processing.
I am keen not to overstate the potential of any individual scientific study. However this story highlights exciting news about a potential relationship between bacteria and migraines. In 2016 The Guardian featured a study that appeared to demonstrate a link between the efficient break down of nitrates in humans and the occurrence of migraines. As I understand the research, migraineurs (people that suffer from migraine) tend to have more nitrate reductase bacteria in both the mouth and in stool samples, than the wider population.
Nitrate reductase genes are responsible for processing nitrates in food and drinks, point being the greater their abundance the more efficient the nitrate processing. So getting more nitrates from food (compared to non migraineurs) may be linked to triggers for migraines. Obviously further research will be needed but the link between nitrates and headaches is not new. What this study is demonstrating is that the key might rest with the microorganisms in the mouth and gut.
Many migraine sufferers are aware of a relationship between certain foods and increased risks of attacks, through chocolate and wine for example. It is also known that certain drugs high in nitrates can provoke severe headaches. When broken down, nitrates lead to increased blood circulation in the cardio vascular system, this increase may be a key factor in migraines. The complexity of the human microbiome, particularly the gut-brain axis, makes demonstrating causality between food and health challenging. However this seems like a promising area of research. Controlling the intake of foods high in nitrates might be a short term solution. But given that fruit and vegetables are rich sources of nitrates, cutting down on them could present a range of risks and benefits. For more information visit the Migraine Action or Migraine Trust websites.
We always welcome your feedback, comments in the text box below. Thanks for Peter for suggesting the subject and as always please read our disclaimer.
Is temperature linked to the quality of your sauerkraut?
In the short time we have been running this blog we have been asked about the optimum temperature for the fermentation process to take place. We have successfully fermented a range of foodstuffs at room temperature, let’s say from 18oC to 22o. There is no method in this, it is simply that Maggie was brought up to leave the fermenting vegetables in the kitchen or a heated utility room. As such we’ve never been tempted to leave them in the garage or garden shed. As different types of cabbage take different amounts of time to ferment into sauerkraut, it always seemed likely that temperature is a variable in the process.
I eventually became impatient not knowing, I was also intrigued by the idea that the quality of our own sauerkraut fermentation could be qualitatively improved by allowing it to take place at a slightly lower or higher temperature. The first two science papers I found dealing with the issue didn’t offer explicit conclusions, however third time lucky! India is one of the world’s big producers of cabbage, the spoiling of the raw cabbage before it gets to the consumer is a significant problem. So Indian interest in fermentation is something that is culturally relevant but also has commercial implications. An article in the Indian Journal of Ecology from 2017, Effect of Temperature on Fermentation and Quality of Sauerkraut provided a lot of useful data.
In an experiment, Pran Krishna Thakur, Payel Panja and Jahangir Kabir tested the quality of sauerkraut produced at a low (15o-20o C), ambient (25o-30o C) and high (35o-40o C) temperatures. The paper is well written if you’d like to know more about yeast and bacterial profiles of sauerkraut fermentation at different temperatures follow the link. However the headline is that the sauerkraut was of a higher quality when fermented at the lower temperature (15o-20o C). This is in line with the general advice, however it’s worth noting that the experiment was undertaken with the shaan variety. I suspect that there may be some variability with different types of cabbage, but that’s a story for another day.
What is gut health? How much does science really know. Where can you get more information from?
The interconnected relationship between microbes and humans is an increasing object of research and general public interest. Microbial communities are all around us, on the equipment you are using now to view this article, in your home, place of study or work. Crucially microbes have a significant presence on our skin and inside our bodies, particularly in the digestive tract, with the highest concentrations found in the colon. It should be pointed out the the consumption of fermented foods is linked to a positive, increased richness in gut flora.
Over the last decade advances in technology have led to improved understanding of the collection of bacteria, fungi and archaea (single cell microorganisms) that make up the human microbiome. More importantly there are ongoing attempts to understand the relationship between an individual’s microbiome and their health and wellbeing. In scientific terms the study of the human microbiome is in its infancy, but there are already a wide range of studies linking microbes living in the human gut to health and wellbeing. Elizabeth Bik has written a journal article outlining this general area of research and its challenges and opportunities. I would recommend The Hoops, Hopes, and Hypes of Human Microbiome Research to anyone wishing to get an overview.
The Bik article was published in 2016, and reflects one perspective (albeit a particularly well informed insight). A search on Google Scholar this morning (13th February 2018) for the term microbiome found over 20,000 entries; each entry likely to correspond to a journal article, book/book chapter, or other document. The point being, that this is a rapidly evolving area of enquiry. The types of human experience which appear to correlate with the microbiome is growing and includes; memory, obesity, depression, cancer, Crone’s disease, the immune system and much, much more. However as Elizabeth Bik points out in her article, the fact the certain microbes are correlated with a particular condition does not necessarily mean they cause it or are caused by it.
If you have a particular interest in gut health my advice is to find some good quality journalism as a starting point. If you need something more then go to the best scientific papers available. In my humble opinion, using one article or piece of research rarely builds a full enough picture. If you find out anything interesting feel free to email us or add it to the comments section below.
How far should we take responsibility for what we eat?
A conversation with a colleague and a question received by email prompts me to remind anyone reading this blog that science is limited in many respects. Scientific claims can be overstated and results can sometimes come about by chance! Our own approach is to consider all evidence on its merits but to apply our own common sense. I would urge everyone else to do the same. Any good scientist is likely to know about the limitations of their findings, and they should be highlighted in their research papers. I would hope for this to be reflected by journalists writing about science.
Part of the motivation for creating this blog is to take a bit more responsibility for my own health, and to encourage others to do the same. We can’t do without reliable high quality science, but that doesn’t mean that research published by scientists or academics is necessarily correct, or should be taken seriously.
In my own field of psychology/contemplative science, research is a starting point and needs to be treated with a healthy scepticism. Once a particular concept has been successfully tested a number of times (replication), only then can it start to be considered as potentially reliable. So if you read something on these pages that interests you, follow the links and check out the source material. And keep the concepts at arms’ length until you feel you can fully engage with the material. All the views expressed on this website are opinions of the contributors and or people writing about gut health. they may not reflect the views of the website owners and must be read in relation to the respective scientific research. Please read our disclaimer.
Can memory and stress be altered by what you eat? The evidence suggests it might be possible.
The more scientific research I am exposed to the less inclined I am to expect simple solutions to complex problems. That said, a report from 2015 highlighted in The Guardian was one of the first accounts of probiotics that turned me on to the potential of gut flora to influence different aspects of health and wellbeing. It was reported that participants in an experiment took a capsule containing Bifidobacterium longum 1714 for a month. As a result they enjoyed lower levels of stress when compared to the control group that took a placebo. Stress was measured in terms of the levels of cortisol (a hormone associated with stress) found in the participants.
A second result of the investigation was that when taking the probiotic, memory function also seemed to be enhanced. The people taking part in the experiment took either the placebo for a month or Bifidobacterium longum 1714, then switched. It was a blind test so the participants didn’t know when they were taking the probiotic or the placebo. The effects of the reduced stress and improved memory were described as small but significant, make of that what you will. But the same effects were found in a similar experiment carried out on mice.
I’m not a great fan of experimentation on animals, not because experiments on animals are rarely replicated in a similar way on humans, or that it generally support poor science. Just because its cruel and not very ethical. However as the data exists I will draw your attention to it. Another study from 2015 indicated that B. longum 1714 had a positive impact on mice cognition and an apparent reduction on fear. So one probiotic strain appears to have an influence on both fear and a narrow range of cognitive function (or that both memory and fear/stress have a commonality that can be meditated by B. longum 1714). The fact that both mice and humans appear to have been effected in the same way is interesting. Although these are tentative findings and more studies demonstrating the same effects are necessary (replication).