6. The importance of a healthy guts – your microbiome
For the past 60 odd years I have never really paid my guts any particular attention unless they were complaining, which was rarely. They were just left to get on by themselves with whatever part they had play in keeping my body going. Now I learn that the cells which make up my gut microbes actually outnumber the rest of my unique “human” cells by 54% to 46% [http://www.bbc.co.uk/news/health-43674270]. That’s right – we have more “foreign” cells with their own unique DNA than we have cells containing our own unique “human” DNA. In fact the guts are of such complexity and importance to the functioning of our body that they are controlled by a second brain (the enteric nervous system) that has been compared in relative complexity and size to that of a cat. Clearly there is a lot more going on down there than I realized.
The collection of micro-organisms, i.e. “bugs”, bacteria, and viruses that inhabit our body, is referred to as either the microbiota or the microbiome. Microbiota refers to the entire colony of bugs that inhabits our body whereas microbiome refers to the total collection of genetic material defined by the genomes (i.e. the complete sets of DNA) of all the micro-organisms that make up our microbiota. In practice microbiome the terms seem to be used interchangeably.
We tend to think of microbes as being harmful and a source of disease and, while some undoubtedly are harmful, we humans are completely dependent on the colonies of “friendly” microbes in our microbiome to help us digest our food. In fact we could not survive without them. Michael Mosley’s book “The Clever Guts Diet” is an eye opener if, like me, you have only ever thought about your guts when they start rumbling. In his book Mosley explains why fast food, highly processed foodstuffs and trans fats are particularly bad for the key bacteria that we need to help maintain our metabolic processes and he provides a lot of guidance on how simple changes can help you improve your microbiome, and hence your health and risk indicators, by eating food that can help strengthen the colonies of microbes. An unhealthy microbiome may also make it much more difficult for you to lose weight, even if you restrict calories.
Microbes rely on foodstuffs called pre-biotics to help them grow. Pre-biotics are special kinds of plant fibre which our bodies cannot digest but which act as a fertilizer for the microbes and help to maintain and grow their colonies. This is one reason why we are encouraged to eat a lot more fibre. Far from just keeping our bowel movements regular a good intake of fibre is vital for the healthy microbiome which supports many metabolic processes and is responsible for the production of certain hormones. The recommended intake of fibre in the UK is at least 30g per day but on average we consume less than half this amount. By tracking my own consumption before starting my diet I discovered that my fibre intake was 15g, so pretty much the UK average, but after six months on the new diet my fibre intake now averages 40g per day. Michael Mosley recommends eating a large diversity of food types including foods of different colours so that the pre-biotic needs of the entire microbiome are best met.
While pre-biotics enhance the microbiome by acting as fertilizer for the bacteria in our stomach, pro-biotics are foodstuffs that enhance the microbiome by adding bacteria directly through consumption. Mosley recommends eating more probiotics in the form of fermented foods like sauerkraut and kimchi as they are a rich source of good bacteria. He also recommends eating home made kefir, which is a fermented milk product similar to yogurt and teeming with live bacteria, as well as home made live yogurt. I confess I had never heard of kefir until I read about it in his book but I started making my own and am now a complete convert (see the next section for how to make your own). Although I never considered my digestion to be particularly sluggish or troublesome I found that consuming about 250g per day of kefir produced a remarkable improvement in my digestion after one week. In addition, my wife, who suffers periodically from mild irritable bowel syndrome, found that the symptoms largely disappeared with regular consumption of kefir. I tend to use kefir in place of single cream for pouring on fruit while mixed with yogurt cheese/labneh and whipped it makes a excellent and healthy substitute for double cream (although not for cooking with as the product will separate with heat).
You can buy pro-biotic yogurt supplements but Mosley is very dismissive of those products based on his investigations and recommends making your own.
A healthy microbiome is about more than just good digestion though. In his remarkable book, “The Diet Myth”, Professor Tim Spector, who has studied the microbiome for a number of years, shows how it underpins so many of our metabolic processes. A reduction of key bacteria through bad diet, illness, or anti-biotics can explain remarkable effects such as why identical twins who are inherently identical genetically, eating the same diet and exercising similarly, can nevertheless develop so one is thin while the other is obese. He also explains why the simple energy balance equation of calories in = calories out and the usual weight loss advice of “eat less and exercise more” just does not apply to some people because of their gut microbes.
If you are interested in improving your gut bacteria then I would strongly recommend reading both “The Clever Guts Diet” by Dr Michael Mosley and “The Diet Myth” by Professor Tim Spector.
6.1 Making your own yogurt and kefir
Making your own fermented milk products like kefir and yogurt is easy. You just need some milk, preferably organic and full fat, a starter culture, and a temperature controlled environment to suit the culture in use. Yogurt makers provide the environment suitable for kefir which requires a lower temperature than yogurt – around 28°C compared to 42°C for yogurt. I used this machine from Lakeland : https://www.amazon.co.uk/Lakeland-Multi-Yogurt-Cheese-Maker/dp/B0752VYY9N/ref=sr_1_1?ie=UTF8&qid=1526852047&sr=8-1&keywords=lakeland+yogurt+maker which allows you to make standard yogurt, Greek style yogurt, yogurt cheese (“labneh”), or kefir.
The process for making yogurt or kefir is essentially the same. Heat the organic full fat milk to boiling point and allow to cool to the correct temperature, stir in the starter, and then place the milk in the machine. Set the required temperature and time and leave the milk to ferment. Yogurt from full fat milk will be ready in under eight hours while kefir, apart from the first batch which may take twenty four hours, is usually ready in four or five hours.
The starter for yogurt is two to three tablespoons of commercial live yogurt and you can experiment with the different types available, just make sure you use live yogurt with no additives or sugar. Repeat batches can make use of your home made yogurt or you can use a fresh culture from a commercial yogurt. If you want a standard light yogurt then just stir the finished yogurt to make sure the whey and solids are well mixed and it’s ready to eat. However I much prefer the thicker consistency of a Greek style yogurt which is obtained by straining the yogurt through the filter basket provided to separate off the lactose rich whey and leave a much richer, creamier yogurt. A couple of hours will suffice to achieve a typical Greek yogurt consistency while a longer straining of six to twelve hours will produce an exquisite yogurt cheese or labneh. Lakeland suggests using 165g of starter yogurt for the large container but I find that a few tablespoons of good live yogurt is all that is needed.
Kefir uses a dried starter similar to yeast and this is what I used : https://www.amazon.co.uk/Kefir-Starter-Cultures-Culture-Sachets/dp/B0772PCPS7/ref=sr_1_7_a_it?ie=UTF8&qid=1526853039&sr=8-7&keywords=kefir+starter+culture . Once you make your first batch you just reserve about two to three tablespoons to start the next batch and you can keep this process going almost indefinitely. Don’t add too much starter or you will end up with a very thick kefir (unless that’s what you want of course). The fermentation process removes the lactose from the milk and Michael Mosley reports that some people who are lactose intolerant can nevertheless eat kefir.
6.2 “Five a day” and fibre intake
When you start delving deeper in to the Government’s Eatwell Guide and pour over the detailed nutritional tables that underpin it you discover a lot of apparent anomalies or inconsistencies between the recommendations for the various nutrients. Take, for example, the recommendation about eating five portions of fruit and vegetables every day [Note : one portion size equals 80g for fruit and vegetables or 40g for dried fruit; one portion of fruit juice is 150ml and one portion of beans and pulses is 80g but these foods can only be counted once per day no matter how much you eat].
Before I started on my Mediterranean diet I tracked my “normal” food consumption for a few weeks to establish a baseline reference. I discovered that I ate at least five portions of fruit and vegetables every day yet my fibre intake was only around the UK average of 15g per day which is half of the minimum recommended fibre consumption of 30g per day, which meant my microbiome was probably not getting enough of the good pre-biotic fibre that is essential for fertilizing the good bacteria in our microbiome. As I migrated to the Mediterranean style of diet my intake of fruit and vegetables increased significantly : by the end of my 6 month weight loss phase my average consumption had become 14.5 portions of fruit and vegetables every day and this increased my average consumption of fibre to around 40g per day.
My conclusion is simple. If consuming more than 30g of per day is a key aspect of a healthy microbiome then you are unlikely to achieve that goal by eating just five portions of fruit and vegetables per day. I think the Eatwell Guide is misleading because it implies that five portions of fruit and vegetables will give you the minimum fibre you need to achieve a fibre intake of at least 30g every day, but you will not come close to that figure on just five portions. Of course you can always take fibre supplements like psyllium husk but that departs from the ethos of the Mediterranean diet where you aim for eating real food as close to its natural state as possible. As Michael Pollan states in his book “Food Rules” : Don’t eat anything your great great grandmother would not recognize as food” which is a very simple guiding principle to follow when you pick up a food packet from a supermarket shelf.