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.
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.
There may be a relationship between kefir and obesity.
I’m becoming increasingly convinced of the benefit of fermentation, that enriching beneficial gut bacteria has widespread effects on wellbeing and health. I’m still near the beginning of this journey and learning all the time. I’ve posted a series of articles linked to kefir, not because I’m an expert, but based of the apparent benefits accrued over the last two months from a small glass of kefir each day. I should also say that Maggie has lost a lot of weight over the time she has been drinking kefir, but, she has also been exercising. However weight loss isn’t my only reason for writing about this subject. A few months ago I felt obliged to take a course of antibiotics, I think it was a mistake ( I am aware of the downsides of this kind of medication) but it’s water under the bridge now. The subsequent decline in my overall health was striking. I started to have trouble concentrating and sleeping, I got a cold, suffered from reflux and saw an augmentation in weight.
I didn’t really connect these things with the antibiotics until I noticed that my bowel movements changed significantly. If you are new to the gut bacteria scene you might feel a little uncomfortable around talk about bowel movements, don’t be. A regular healthy bowel movement is one of the signs of a healthy balance in gut bacteria. So when I noticed I wasn’t going to the toilet regularly I though about the possible impact of antibiotics on my gut. I started to take kefir more regularly whilst keeping my usual prebiotic and probiotic consumption at the same level. The difference was gradual but pretty much everything started to improve after about five days. Two months later things are back where there were before the antibiotics. I’m much healthier, bowels are back to normal and……..I’ve lost weight without any exercise.
This isn’t a morality narrative about the harm of antibiotics. I believe antibiotics represent a life saving technology, and in the right place and time are essential. It’s their inappropriate overuse which I think is harmful.
My own anecdote is that I think it took two months to return the state of my gut bacteria to somewhere like normal, and I am a daily consumer of natural prebiotics and probiotics. In all of this story things pretty much fitted my modest understanding of the underlying science except the weight loss. I know that lack of diversity in gut bacteria is correlated with obesity generally but I hadn’t come across any research papers linking kefir to weight loss. If you can improve your gut health and pull your body weight closer to its optimum level this has to be a win-win. So I started to look through the scientific literature. The most recent research is featured here.
Are their differences in traditional and commercial kefir?
This is the second part of the feature, you’ll find part one here.
Despite my scientific training, regular followers of my blogs will have realized I have an established scepticism for extravagant scientific claims. I am a fan of science generally but feel the need to maintain a discriminating eye and treat each scientific claim on its merits. However a recent study into the relationship between kefir and obesity has been worth a closer look.
In a research paper titled Traditional kefir reduces weight gain and improves plasma and liver lipid profiles more successfully than a commercial equivalent in a mouse model of obesity, Bourrie, Cotter and Willing found that kefir appeared able to meditate metabolic health. This study compared the ability of traditional with commercially produced kefir to mediate mouse weight gain, plasma cholesterol, and liver triglycerides. Four traditional and one commercially available kefirs were used in the experiment. Commercial kefir was shown to have no beneficial effect whilst two of the traditional kefirs demonstrated a reduction in the rate of weight gain and increase in blood cholesterol. This was (as far as I know) the first ever study comparing mass produced with traditionally produced kefir, so the research must be regarded as preliminary. It was a study with mice so the extent to which results can be generalised to humans is uncertain.
The research concluded that when also considered in relation to the modulation of the gut microbiome, traditional kefir has the potential to mediate obesity through the improvement to metabolic dysfunction.
The report also explained that different forms of traditional kefir do not generate identical microbial populations. It is assumed that this could be linked to variable health benefits. Further that whilst Lactobacillus, Lactococcus, and Leuconostoc would be expected to be found in most forms of kefir, acetic acid bacteria was not found in a majority of commercial products. Research has also suggested that traditional kefir possesses highly complex fungal communities (including, S. cerevisiae, Pichia fermentans, Kazachastania unispora, and Kluyveromyces marxianus and lactis) not always found in commercial products.
In conclusion, three take home points:
This is preliminary research, it’s early days!
Traditional kefir may support improved cholesterol and fatty acid metabolism.
Traditional kefir appear to offer a much greater microbial diversity to the host than commercially produced kefir.
Having been experimenting with DIY kefir for a while, I thought it was time to share some of the key points we have discovered. This is not an exhaustive guide, follow this link for more general resources. The first thing to consider is that kefir is created by fermenting bacteria, therefore you need to follow reliable instructions. Our ten point guide contains tips that may help you on your way to a more positive experience.
Decisions, decisions, decisions: Kefir can be made using powdered culture or live/dehydrated grains. You can also use a range of liquids to create kefir, milk, water, juice, coconut milk etc. There are subtle differences in how you approach these different processes. Think about it before you start.
Cleanliness: Given that you are going to be growing bacteria you do not want to introduce anything that will pollute or taint your product. Make sure everything that comes into contact with the kefir is as clean as possible.
Quality: I generally aim to use good quality milk/juice/water in order to have the best quality product.
Water: Chlorinated water (tap or bottled) is generally felt to be unsympathetic to both the grains and the product so aim to use filtered water as far as possible in your fermentation operations. Don’t expose the grains to very hot or very cold water.
Temperature: Typically milk takes around 20 – 24 hours to ferment into kefir at a room temperature of 22–25°C. If this sounds imprecise it reflects the range of factors linked to production. A golden rule is to try and avoid extremes of hot and cold.
Observation: At the outset check the fermentation process regularly, you can’t expect consistency in kefir production unless you control all of the relevant factors. In a normal family kitchen having the oven on or windows open can change the time needed for optimum fermentation. I always check the product (visually) after 12 hours and thereafter at regular intervals.
Avoid: Don’t use of anti-bacterial hand cleaners when working with fermented product.
Manage the grains: Most of the advice says you can handle the grains but your hand should be spotless.
Augmentation: Grain populations increase over time, you will have to remove grains every two weeks or so to keep the fermentation process stable.
Cleanliness again: After every batch make sure that all containers, implements and any gauze or cheesecloth covers are as clean as possible.
Kefir appears to offer significantly greater benefit than commercially produced probiotic drinks.
Dr Michael Mosley has been helping to run a study for the BBC looking at the relative benefits to gut health from a range of products. Volunteers and scientists collaborated to try to discover which of three probiotics/prebiotics had the biggest positive impact on gut bacteria.
The first product was a commercially available drink, branded as a probiotic and available in major supermarkets. The second item up for comparison was kefir, a traditional milk and yeast fermented substance, a little like yogurt. These first two foods were compared with vegetables high in natural prebiotic fibre called inulin. Inulin is found in range of foods including chicory (chicory root is a rich source) and scallions (onions, leeks and garlic).
The poorest preforming of the three in this trial was the probiotic drink. The participants in this group demonstrated a modest (statistically non significant) change in lachnospiraceae gut bacteria. Conversely significant changes in gut flora were seen in the group consuming prebiotic fibre. The people that consumer kefir enjoyed the most positive increase to gut bacteria.
It should be pointed out that any comparison between prebiotics and probiotics is not a like for like test. Prebiotics deliver the food that supports existing bacteria and create the conditions for further colonization. A probiotic is intended to introduce microorganisms directly into the body.
The BBC study concluded that traditionally produced fermented foods (or even home made versions) may offer the greatest benefits to consumers in terms of increased gut flora. A key problem with mass produced fermented foods and drinks is pasteurisation. Pasturised goods are regarded as safer, which also correlates to a longer shelf life. By comparison traditionally made kefir has to be consumed in a relatively short space of time. This is perhaps the choice we consumers face, if we want maximum health benefits from the food we make or buy we may have to sacrifice some of the convenience of long sell by dates.
A basic guide to gut health, key terms defined and explained.
Understanding gut health; 1 the basics
The scientific investigation of gut bacteria and its relationship to wellbeing is at a very early stage. There are discoveries every week that support, coexist with or contradict earlier findings. It’s a rapidly developing and dynamic area of human knowledge. The good news is, there are many resources available to anyone who wants to understand and take control of their own health through diet.
As a starting point there are a few concepts that are best understood at the outset. Not everyone uses these terms in the same way but try these definitions as a starting point.
Microorganism is widely used in talking about gut health, it is a general description for any organism that is too small to see with the naked eye. Some scientists prefer not to use the word but you are likely to come across it widely if you start reading about gut bacteria. Bacteria, viruses, archaea and fungi are all typically included in the term.
Microbiota is generally used to denote the population of microbes in any given community or system. Flora appears to have largely the same meaning as microbiota and appears interchangeably. For example gut flora means the same thing as gut microbiota.
The aggregate of all the genes of an entire population of microorganisms in any environment is described as a microbiome.
Typically scientists divide human microbiota into populations linked to their environment, such as skin, mouth, nose, digestive tract, and in females also the vagina. The largest population of microbes occur in the digestive tract, also known as the gut. Bacteria are the largest type of microbe in the human gut and bacteria reflects the dominant interest of scientific research. Gut bacteria are the main recipients of the benefits of prebiotics and probiotics, that is why the term gut bacteria and gut health is so prominent in media accounts of research findings. Technically speaking the plural of bacteria is bacterium but you will rarely see this outside of science journals, bacteria is typically used as the singular and plural form in most everyday situations.
A key point to make is that the gut has an important two way communication system with the human brain. That means to think of fermented food and drinks as only involved in what happens in the intestinal tract is a mistake. What we eat and drink has has the potential to exert a widespread influence across a number of systems.