Your diet can play a significant role in your chances of becoming obese, suffering from asthma or a range of other illnesses.
Discovery, a general science programme from the BBC World Service, has put together a helpful three part guide to the human microbiome. It is made for the wider World Service audience so it presents the issues in an interesting but accessible way. The discussion of the subject matter is engaging, and important contributions are made by leading scientists in the field such as Prof Rob Knight, from the University of California and Prof Tim Spector from Kings.
The show provides a general outline broken down into three parts; Manipulating Our Hidden Half, Dirt and Development and Gateway to the Mind. The idea that humans (in common with other animals) have not one but two genomes is central to this mini series. Our human genome is the one handed down to us through our parents, set in stone at conception. The so called second genome is made up of a vast pool of genetic diversity present in the microbes found throughout and within our bodies. The Human Microbiome Project has begun the process of analyzing the large number of microbes present in us. Two key issues that have started to excite scientists in recent years are,
the extent to which microbes can influence human health and experience.
the ability of individuals to alter their own microbial profile.
For example, it is generally observed that increased diversity of different kinds of helpful bacteria in the gut, is correlated with improved wellness. Studies in obesity, allergies, asthma and auto immunity suggest that gut bacteria may have a crucial role in meditating our health. This opens up the prospect that lifestyles remedies such as changes to diet may offer us significant potential benefits. It also raises the question about the long term benefits of medication known to have a detrimental affect on gut bacteria such as antibiotics.
This then takes us back to the discussion of probiotic and prebiotic food and drinks. When you consume products rich in helpful bacteria (probiotics) or the soluble fibre known to support microbial diversity in the large intestine (prebiotics), you are likely to be improving your health in a number of ways. It cannot yet be said that there is a direct causal relationship between your diet and certain illnesses. However the scientists are starting to think of gut bacteria as increasing or decreasing the chances of suffering from particular health problems.
At the time of writing all three programmes were freely available online or to download here.
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.
Eat more raw, to get the most from prebiotics and probiotics consider how you prepare your food.
As a fermentation fan and a non-strict vegan, eggs are not normally part of my diet. However a recent scientific study that came out of China got me thinking more generally about food preparation. In the UK eggs have enjoyed a love-hate relationship with food experts and nutritionists. In 1988 Health Minister Edwina Currie announced that UK egg production was badly affected by salmonella. Although she lost her job, uncertainty over the benefit of eating eggs remained. There has also been a long standing disquiet over the suffering experienced by hens in the ‘industrialised’ production of eggs. Scientists still suggest that there may be a correlation between egg consumption and a number of health problems.
Conversely a new large scale study from China has suggested eggs may actually reduce risk of stroke and heart disease. The current advice from the NHS is that the cholesterol found in eggs is less of a health problem than the effect of saturated fat from the cooking process. Indicating that boiled or poached eggs may be significantly better for you than fried. This is not an endorsement of eggs as a health food per se’ but it draws attention to the strong relationship between health and food preparation. So what has this got to do with fermentation, prebiotics and probiotics?
One of the reasons we cook food for a sustained period is to destroy potentially harmful bacteria. It follows then that if food, such as sauerkraut is cooked at a high temperature for a sustained period much of the helpful bacteria will be removed. People starting to think about gut-bacteria from scratch (like us), might be surprised to know that commercially available products thought to be ‘probiotic’ may in fact be pasturised (heat treated) or made from pasturised ingredients.
This is one of the reasons why home fermentation is taking off in such a big way. There are certain challenges to delivering high quality, probiotically rich foods, safely and at a competitive price. So if you are purchasing probiotics check the labels to ensure things are as they appear, in particular watch out for the word ‘pasturised’. This is not so say that you can’t cook ‘live’ yogurt in a curry or sauerkraut in a pork casserole. It’s just you may be loosing a lot of the bacterial benefit.
A quick word about prebiotics. Prebiotic is a blanket term for any food ingredients likely to enhance the growth and development of beneficial bacteria, typically (but not limited to) those found in the large intestine. In order to arrive at the large intestine, food needs to be structurally able to resist breakdown in the stomach. Foodstuffs in this group can (loosely) be thought of as ‘dietary fiber’. If you do a little research in this area you’ll find that many of the most useful prebiotics are in fact raw vegetables. That is because cooking can limit the probiotic benefit effect of certain foods.
There are many valid reasons why people may wish to cook fresh fruit, vegetables and dairy products. The take home point is that if you don’t already, you might wish to take a look at how you prepare your food and the extent to which you are maximizing your support for beneficial gut microorganisms.
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.
The overuse of antibiotics is a major health concern. Probiotics may support the lower consumption of antibiotics by boosting overall health in humans and animals.
I am in the process of writing a basic guide to probiotics, but a general description is,
‘microorganisms contained in some food and supplements that have proven and assumed benefits to human and animal health’.
A key point at the outset is that it is hard to prove causality in such matters. Demonstrating correlation (people that have particular gut bacteria tend to have or not have a particular illness) is much simpler. The evidence linking probiotics and health is both causal and correlational. The point of probiotics is to change (improve) the profile of gut flora so that it has more positive and less negative microorganisms. This is a long road of which we are at the beginning.
Antibiotics are drugs designed to destroy or inhibit the growth of bacteria harmful to humans, animals or other organisms. I acknowledge the potential lifesaving benefits of antibiotics, they are an important part of modern healthcare. But the widespread overuse of antibiotics in industrialized societies is creating superbugs, bacteria that are resistant to all known antibiotics. This problem was the subject of the film Resistance which I recently saw on Netflix. The issue of superbugs is not new and the discoverer of penicillin, Alexander Fleming discussed resistance in the mid 1940s. If you subject bacteria to an effective antibiotics most will die off, but surviving bacteria can develop resistance to that antibiotic. If you repeat the process often enough you risk creating bacteria over time, that become resistant to every antibiotic they have been exposed to.
Sometimes humans are given antibiotics when they are not needed, and so we may carry around bacteria that have a resistance to some antibiotics, this is a problem in itself. A key point that the film Resistance makes is that contemporary farming methods can involve the routine administration of antibiotics to hundreds of millions of animals every year. Antibiotics appear to make some animals grow bigger, thus increasing their cash value. However intensively farmed animals can live in insanitary conditions, exposed to fecal matter for most of their lives. Forcing animals to live in an environment where high levels of dangerous bacteria are present, thus necessitating the use of antibiotics as a routine measure, can be described as a perfect breeding ground for superbugs.
The standards of animal welfare vary from country to country and the use of antibiotics in the EU generally is lower than some other parts of the world. But it’s still a major problem according to a recent report. Conceptually the idea of eating animals is increasingly unacceptable to many people. However the logic of forcing animals to live in terrible conditions their whole lives, only sustained by large amounts of antibiotics is obviously flawed. Not only are people eating animals that have endured life long suffering underpinned by the consumption of drugs. But this process may also be creating bacteria resistant to those drugs. The use of last-resort antibiotics for humans such as colostin, is increasing according to official data. When colostin is used it can indicate other antibiotics were ineffective against the harmful bacteria.
So what has this got to do with fermentation and probiotics? Firstly antibiotics generally kill and inhibited some good bacteria. Where health is at risk this is clearly an appropriate course of action. However as the importance of gut flora to health becomes better understood we should consider the need to maintain gut bacteria at healthy levels. Secondly the better our overall health the lower the risk of illness and presumably the less need there will be to take antibiotics. Just to be clear, probiotics are not a substitute for antibiotics, there are some very dangerous bacteria in our environment for which antibiotics may be the only cure. My position is to abandon the overuse of antibiotics in animals and humans so that when we (and animals) get really sick we will have antibiotic treatments that continue to work. The third point is eating animals that have lived a life in potentially dangerous bacteria, sustained by routine antibiotic consumption seems irrational. Wouldn’t it make more sense to maintain animals in healthy conditions, with feed rich in probiotics, reducing the need for antibiotics in all but essential cases?