Fibre is an essential part of the human diet, strategic reviews indicate that consuming just 30g of fibre a day is correlated to reduced risk of colon cancer, type-2 diabetes, heart attacks and strokes.
For most of us there is a simple thing we can do to improve our short and long-term health, eat more fibre! The role of fibre in regulating digestion has been understood by humans for hundreds of years. But the full benefits linked to fibre (also known as roughage) are only just starting to be understood. A recent study published in The Lancet1 analysed a wide range of research and found that a shortage of fibre in our diets is linked to greater risks of type-2 diabetes, bowel cancer, heart attacks and strokes. In addition people that eat more fibre tend to have lower weight, lower blood pressure and reduced cholesterol levels. Amazingly the research suggested that consuming a mere 30g (1oz) of fibre a day was sufficient to deliver the full range of health benefits. To put this into some kind of perspective the 30g target can be reached by consuming four slices of brown bread, eating a handful of nuts and seeds in addition to the regulation five portions of fruit and veg a day. In essence it is available to most of us with only a few small changes to our eating habits.
Fibre consumed through our diet can be divided into two types, soluble and insoluble. Soluble fiber is generally though of as a prebiotic, which means it supports communities of helpful bacteria in the gut microbiome. Insoluble fibre does not dissolve in water and typically passes through the digestive system aiding bowel movements. Most fibre rich foods contain soluble and insoluble elements, today food science is more concerned with the total amount of fibre rather than the different forms (cellulose, pectins and beta glucans) we eat.
In summary; fibre is an essential part of the human diet, strategic reviews of the available evidence strongly suggest that consuming 30g of fibre a day is correlated to reduced risk of colon cancer, type-2 diabetes, heart attacks and strokes. There is a growing body of evidence that fibre also plays an important role in maintaining helpful bacteria in the gut microbiome.
Blueberries appear to offer a wide range of benefits including supporting guthealth.
Being a meditation scientist I often write about lifestyle choices that support augmented brain function and structure. As a general rule food that is associated with a healthy brain also positively correlates with improved general health and well-being. So having just blogged an article explaining how blueberry consumption can reduce effective brain age by up to 2.5 years I looked up potential relationships between blueberries and the gut microbiome.
Berries in general and blueberries in particular are good natural sources of polyphenols and therefore limit the effect of oxidisation, a cause of cell damage. But we also know that polyphenols lead to a healthier gut through the creation of metabolites which in turn support communities of beneficial bacteria.
As we age, chronic diseases become more likely1, when low grade inflammation is an underlying factor scientists refer to this as the “inflammaging” syndrome. In gut health inflammaging is linked to a weakening of a number of internal systems (homeostasis) including a reduction in the efficiency of the immune barrier. In experiments with mice it was suggested that polyphenols reduced intestinal inflammation and led to the modulation of the gut microbiota. The evidence is that berries are rich sources of polyphenols and so are likely to have a positive impact upon chronic diseases linked to gut health, particularly in older populations.
According to the Blueberry Council the benefits of blueberries extend beyond inflammaging.
Experiments have demonstrated an improved insulin response in blueberry-fed mice when compared to controls.
Further evidence for augmented cognitive function in animals and humans has been found.
There are also preliminary studies supporting a relationship between blueberry consumption and reduced growth in cancerous cells.
Polyphenol is found in a wide range of fruit and vegetables as well as nuts and pulses. Here are some of the top 100 food sources of polyphenol according to a study published in 20102.
Health risks of bacon and other processed meats hit the headlines.
I’ve been reading about the potential health risks linked to meat consumption for decades1. The evidence of a relationship between processed meat products in particular and serious illnesses including cancer has been established for many years. So recent and widespread calls to rid bacon and ham of nitrates comes as no surprise. In fact in some senses it feels like a long overdue and underwhelming response.
Needless to say The British Meat Processors Association stand by their bacon and maintain that nitrates are ‘authorised additives’. However the dispute over the risks and benefits of nitrates in processed meat begs the question, why don’t we do away with processed meats altogether? Meats are processed to modify the taste or extend the shelf life, products include bacon, sausages, hot dogs, salami, corned beef, beef jerky, ham as well as canned meats. Until we know more about the relative health risks of the different products it might be advisable to avoid them all.
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.