The importance of the microbiome to human health is just starting to emerge, but our attitude to gut health hasn’t always been this enlightened.
Just a heads up for anyone interested in learning more about the changing relationship between humans and gut health. A short series The Gut Instinct: A Social History has been broadcast on BBC Radio 4 this week over five 15 minute episodes. At the time of writing the transmissions were still available on the BBC iPlayer here.
The concept was to explore how humans related to digestive processes and gut health across culture and time. There’s a lot of general information linked to the microbiome, some directly relevant to us today. The programme was written and presented by restaurant owner Tim Hayward and it seeks to offer an account relevant to a general audience, setting out major historical landmarks as well as important contemporary issues. Unusually for a British show, we actually hear adults talking about bowel movements and human waste in a practical and informative manner. The five-episode titles reflect the general content of the series (Gut Culture, A Window into the Gut, The Language of the Gut, The Disease of Civilisation and The Gut Speaks). Don’t expect much detailed science but I’d imagine anyone who tunes in to pick up some new morsels of gut knowledge, total listening time is just 75 minutes.
Diet is becoming a crucial factor in maintaining estrogen levels in post menopausal women.
Menopause and health, diet is crucial
The number of women living with the menopause is growing, therefore more people are at risks from illnesses connected with life after the menopause. A recent study investigating estrogen levels and gut health in post menopausal females found a relationship between microbial diversity (the different types of microbes) and circulating estrogen. The implications of this are huge because low estrogen is linked to a wide range of health issues. Typically the diversity of microbes in the human digestive system (gut microbiota) can be altered with changes to diet, for example a greater emphasis on plant based foods, and the use of probiotics and prebiotics. This suggests that women’s health generally, including fertility might be improved simply through alterations to diet.
One of the most important factors in the amount of circulating estrogens in women is the gut microbiome (the population of microbes in our gut). The greater the diversity of gut bacteria generally speaking the higher the levels of estrogen will be. Low levels of estrogen are associated with a wide range of illnesses in older women such as: obesity, cancer, polycystic ovary syndrome, heart disease and even cognitive function. It is suggested that bariatric surgery, fmt and medication (metformin) can alter the gut microbiome and therefore limit estrogen-driven disease. But the evidence suggests that changes to diet alone may be able to have a significant impact on estrogen levels
I’d like to highlight four of the issues raised by the research:
There appears to be a strong relationship between what women eat and levels of circulating estrogen.
Different treatments exist to increase estrogen, but dietary changes alone might deliver significant benefits.
The benefits of increased circulating estrogen through improved diet may be available to women of any age and might be linked to improved fertility.
This study reflects a general pattern in health seen in human microbiome research, that a healthy gut is linked to reduced risks of developing a wide range of illnesses.
It feels like this latest study into the effectiveness of regular doses of an 11-strain probiotic cocktail might set the cat among the pigeons. If we are naturally resistant to new bacteria how can we evaluate the effect of probiotic rich foods and supplements?
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.
Latest study links processed meat to increased risks of breast cancer.
Latest research confirms processed meat increases breast cancer risk
I generally have mixed feelings writing about lifestyle choices correlated with increased risks of cancer. I don’t think provoking people’s fear is usually beneficial and I don’t see my role as pushing people towards or away from things that I feel are important. Even as a vegetarian and now a non-strict vegan I have never found that scare tactics draw people into thinking about their own wellbeing or that of others. I do retain however a genuine sense of gratitude to the people that educated me about the relationship between diet, gut bacteria and mental and physical health. So if I highlight the latest research reviewing the dangers of eating processed meats it does reflect my own thoughts but I hope that it offers readers the opportunity to make an informed choice about what they eat.
An understanding of the health risks of eating animal products has been around for decades, and the scientific evidence of potential dangers linked to meat consumption increase week to week. The latest study to hit the media, reports that women who eat processed meat products such as bacon and sausages, have a 9% increased risk of breast cancer compared to women eating low levels of those products. This is not the first (nor the last I’ll bet) study that links meat with increased risks of developing cancer. But once you look into this issue further you realize that eating processed meat is a triple whammy! Firstly you have the statistically evidenced increased risk of breast cancer, secondly there are also greater risks of a wide range of other health problems. But also that while you’re eating potentially harmful animal products you are not consuming health supporting fresh fruit and vegetables.
As a society we know that the mass, unthinking consumption of animals and animal products isn’t helping us individually or benefiting the wider society. I’m an advocate of a healthy diet based primarily on plants, including fermented products. The indications are that even if you eat fresh fruit and vegetables alongside your processed meats, the benefits to your gut health are going to be limited. A final point to consider is that if we know that the type and quality of the food we eat affects our own health, what is the impact on us of the diet of the animals we consume? If animals are being reared in harsh unsanitary conditions, dependent on antibiotics for their survival and with poor quality fodder, should we be surprised if eating them increases our risks of poor health?
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.
Cabbage offers vital support in resistance to cancer. New research suggests new molecular evidence.
This blog reflects a growing interest in the benefits of consuming fermented food as a way of improving health and wellbeing. Cabbage is a popular vegetable in Europe, and it is one of the simplest things to start fermenting at home. Most parents would have urged their children to ‘eat up your greens’ at some point, but the real value of this advice is only just starting to emerge. Cabbage is part of the cruciferous family (brassicas) which includes lots of vegetables long associated with a healthy diet such as kale and broccoli (wasabi and horseradish too incidentally). Including them in your diet has long been recognised as a good idea. With a growing understanding of the link between lactic acid fermentation and good gut health, cabbage is being thought of as a superfood, able to increase protection against a wide range of health problems.
News published today on the BBC website adds yet another dimension to the benefits of eating cabbage. Scientists at the Francis Crick Institute have identified anti-cancer chemicals created in the process of digesting brassicas, including cabbages. It is supposed that a chemical (indole-3-carbinol) created when cabbage is broken down in the body, encourages the healthy renewal of the bowel lining. The cited research was not carried using fermented cabbage, however the long standing association between sauerkraut consumption and healthy bowels suggests to me that fermentation may have a favorable link with indole-3-carbinol production.
This research was carried out on mice so how it translates to humans is as yet uncertain (is the use of mice really necessary?). And as already mentioned this wasn’t a study on fermented cabbage.
Finally I just want to remind everyone of the importance of eating organically whenever possible. In a recent court case in the US, a man was awarded £226m in damages after claiming that his cancer was caused by a weedkiller that included the compound glyphosate. Despite being developed by a powerful chemical company (Monsanto), glyphosate has been attracting health concerns for some considerable time. France plans to ban it’s use within three years and at least one study by the UN argued it is probably carcinogenic in humans. While washing vegetables before consumption is always good practice, many chemicals used in agriculture like glyphosate are absorbed through foliage and roots. I’m uncertain of the extent to which glyphosate is present in the production of brassicas, but going organic is the only way to be sure.