Evidence suggests the causes for Parkinson’s disease may originate in the gut.
The Guardian1 ran a story yesterday, pulling together some of the latest evidence linking the origins of Parkinson’s disease to the gut. It has long been thought that when a protein called alpha-synuclein is misfolded and clumps together in the brain, it is associated with nerve damage and a reduction in dopamine. This, in turn, is presumed to be responsible for the deterioration in the control of speech and movement, two of the key symptoms of Parkinson’s disease. But recent research in this field has been looking at the gut as a potential point of origin for the misfolded alpha-synuclein.
The direct two-way channel between the gut and brain (the gut-brain axis) is being seen as an increasingly important mediator of human health. A recent study with mice has added weight to the hypothesis that the misfolded alpha-synuclein originates in the intestinal tract and use the vagus nerve to travel to the brain. This follows earlier findings that indicate having your appendix removed reduces the chances of developing Parkinson’s in later life. Taken together these studies signpost the possibility that prevention of Parkinson’s disease could focus on the gut rather than the brain.
However, there are a number of further steps that need to be made, not least a convincing explanation of what causes the misfolding of alpha-synuclein in the gut. As such, it is premature to conclude that the primary cause of Parkinson’s disease originates in the digestive tract. But this latest evidence underpins the importance of the gut in human health more generally. Understanding how to maintain a healthy gut microbiome through the use of prebiotics and probiotics is entering the mainstream. In addition, science is also drawing our attention to the pressing need to avoid substances that degrade or limit gut health, such as the chemicals that are present in a wide range of foodstuffs.
Could gut bacteria and therefore diet hold important secrets about the causes of fibromyalgia syndrome?
Perhaps I should begin by describing the range of symptoms most commonly associated with fibromyalgia syndrome (FMS). According to the NHS1, increased sensitivity to pain is typically experienced by sufferers of FMS, it can be so severe that even a light touch can be a problem. There is evidence2 that when fibromyalgia patients are exposed to pain-inducing stimuli, they demonstrate a stronger neurologic pain signature that a control group (people without fibromyalgia). However, the pain is not restricted just to the sense of touch, it can also be provoked by things a person might see, inhale or eat. People living with FMS might also experience great tiredness, problems sleeping, muscle stiffness and spasms, irritable bowel syndrome (IBS), poor cognitive function and headaches. The syndrome is also frequently correlated with anxiety and depression. FMS can be a life-changing and debilitating condition, unfortunately, the causes are currently unknown, although abnormal levels of brain chemicals are thought to play an important role.
If the findings of a scientific study published last week3 are confirmed, FMS may have to be viewed in a totally new light. A team of scientists compared the gut microbiomes of 77 women with FMS to a control group. Significant differences were identified in the composition of the gut bacteria of these two groups. Through algorithmic analysis, the variance in the respective groups of microbiomes was found to be linked to FMS related issues (more than any other cause). So put simply, if the results translate to the wider population, people living with FMS are likely to have different gut bacteria than those without FMS. There is not any suggestion of causality here, that gut bacteria alone is the cause of fibromyalgia. However, we cannot avoid the speculative idea that changes to gut bacteria could mediate the symptoms experienced by FMS patients.
This is just one study, the results have to be replicated in order for provisional findings to be confirmed. But if demonstrated to be reliable, the evidence would signpost new ways to understand and possibly treat FMS. For example, can the composition of gut bacteria be changed away from that typically found in someone with FMS, to a profile resembling someone without FMS? If any such change led to a reduction or elimination of fibromyalgia symptoms, a new way to deal with this illness might be developed, perhaps linked to diet. This is particularly interesting when considered alongside studies that suggest chemicals found in everyday food such as bread may be able to disrupt the gut microbiome.
It will take a sustained period of research in scientific and clinical environments to confirm any of the speculative hypotheses discussed here. But at least two important issues emerge from this latest evidence. Firstly, that the gut-brain axis can be considered as a potential mediating factor is FMS, and secondly, that gut microbiome alteration may be correlated with non-visceral pain more generally. Therefore eating or not eating ‘healthily’ may be linked to an increasingly wide range of human health conditions.
Evidence is mounting that there is a relationship between what we eat and dementia.
I trained as a cognitive scientist/neuroscientist originally because I wanted to know more about how people could lower their risks of developing dementia in general and Alzheimer’s disease (AD) in particular. My interest in fermentation comes from exposure to research indicating that gut bacteria is correlated to a range of physical and mental health conditions. That if you have too many or two few of certain types of microbes within your digestive tract, then you are more likely to experience better or worse health.
Imagine my interest then when I receive details of research that stated,
“All the results suggest that AD may begin in the gut.”
This conclusion from Hu, Wang and Jin appeared in their 2016 study Alzheimer’s disease and gut microbiota. Clearly if the results stand up and can be replicated this will change much of what we know about AD, and how it might be treated. There is a growing body of research that has linked AD to diet, it is widely discussed in the vegan and vegetarian communities. But Hu, Wang and Jin take the current thinking further; that AD is not just linked to what we eat per se’ but the prebiotic and probiotic effects of our diet. This research suggests that future treatments for AD are likely to come in the form of dietary or microbiotial interventions. The investigation covers a wide range of evidence, the scientists also draw attention to known links between gastrointestinal diseases and reduced cognitive function as well as Parkinson’s Disease and abnormal levels of gut microbes. If you’re puzzled as to how the gut influences the brain, look into the gut- brain axis.
As a general rule I’m cautious about the findings of academic studies dealing with complex areas of human health like AD. There are such a wide range of factors able to influence wellbeing that to isolate and demonstrate causality is not a simple matter. There is also evidence linking a number of other behaviours (meditation, mindfulness) to reduced risks of neurodegeneration. So that if there is a correlation between both meditation and gut bacteria with lower risks of developing AD, we need to think about how it might work.
Anyone who has been around the meditation community for a while may have noticed a few things about regular meditators. They tend to be relatively calm and their diet and lifestyle tends to be a little different from the mainstream. For example I’ve observed that meditators appear to smoke tobacco and drink alcohol less than the general population. Anecdotally I have found more vegans and vegetarians in the meditation community than my non-meditating friends. You can see from these speculative ideas that the relationship between gut bacteria and AD could hold up even given the evidence linking meditation to lower risks of neurodegeneration.
Whilst this study in isolation does not prove that AD begins in the gut, it signposts further areas of potential research. We now need to look for more specific evidence and ‘joined up’ explanations. It seems that there has never been a better time to think about the benefits of bringing fermented food into your diet and protecting your gut health as far as possible.
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.
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There is a two way communication system between the gut and brain, this is one way that gut microbiota mediate our health.
The growing excitement over the role of gut bacteria is being fuelled, in part, by the realisation of the potential role of the gut – brain axis. The gut-brain axis is the hard wiring between the digestive tract and the brain. That is to say a direct communication link passing information between neural, hormonal and immune systems. A key point to make is that the communication is bi-directional, that means the brain talks to the gut and that the gut talks to the brain. Thus the microbiota (gut bacteria) and metaboloites (small molecules that are the product of metabolism) may be in reciprocal communication with different parts of the brain. While this has a direct and obvious impact on processes related to eating and digesting, there is rising evidence that our gut flora may be significant factors in physical and mental health.
The relationship between emotions and the digestive system is one of which we are intuitively aware. For example, feelings of love often manifest as ‘butterflies’ in the stomach. Engaging in team sports enables you to observe pre-match nerves in both yourself and others; the digestive system often plays an obvious role in how some people deal with tension! There is evidence that stress is a mediating component in gut microbiota, perhaps through increasing or decreasing the optimal conditions for certain types of bacteria to flourish.
New studies are suggesting that individual microbiota may be influential in functions as apparently disparate as memory and fear. It is not known what the basis of the relationship is, where the causality can be found. But that there is a correlation between what is in our gut and how we experience life in terms of mental and physical well being. The take home point is that many of the things we eat and drink are able to positively and negatively influence our health. By taking more interest in what goes into your stomach you might do yourself a power of good.