Around 3.5 billion years ago, the first hint of life appeared on earth. They are thought to have been tiny, single-cell organisms resembling bacteria, and their successors dominated the planet until today.
It took another few hundred million years of evolution for a strain of bacteria to come along that would produce oxygen. A few hundred million years more for bacteria to evolve into the complex cells required for all plant and animal life, ultimately including human life, to develop.
Bacteria, microbes, germs or bugs – they’ve always had a bad rap. But that’s understandable as good bacteria tend to get lumbered with harmful bacteria and the viruses, fungi, parasites, and protozoa that pose risks to our health.
It’s also a near impossibility to get your head around the statistics. Situated in several parts of our bodies -- nose, mouth, lungs, skin, colon, the sexual organs, and throughout the gut -- these microbes, of which some 90% are bacteria, count in the tens of trillions. Combined, they weigh around 2kgs (4.4lbs), making the microbiome larger than any human organ other than skin.
And like our organs, we couldn’t survive without them. A fact that only became apparent through the discoveries scientists started making towards the end of the 1990s.
The bacteria in our digestive tract – the gut microbiome or gut flora – helps digest food and extract the nutrition we need to stay healthy. Not only that, the good bugs fight off the nasty bugs that cause us harm.
Over the last 20 years or so, there has been a flood of astounding discoveries concerning the microbiome’s effect on a wide range of health benefits. Like, for instance, some strains of bacteria can help us to maintain a healthy body weight.
In addition, it’s believed that the microbiome helps regulate high blood sugar levels that can lead to type 2 diabetes and contributes to keeping cholesterol below the levels that can lead to heart disease. The microbiome is also an essential part of the body’s front line of defence against infections.
Research also suggests that the gut microbiome may improve mental health by reducing the symptoms of stress, anxiety, and depression. All achieved by a physiological wonder called the enteric nervous system that connects the brain to the 100 million or so nerve cells that line your gastrointestinal tract. [MWG1] [MWG2]
But for the microbiome to look after us, we need to look after it with a diet rich in probiotic foods.
Fermentation: Preserving food, preserving life
So what exactly are probiotic foods? They’re foods that contain colonies of live, active bacteria – the good bacteria – that nourish and support the gut microbiome. And as is generally accepted, some fermented foods and beverages are a rich source of natural probiotics.
The fermentation process occurs naturally, providing suitable conditions: a warm, oxygen-free environment that allows microorganisms – bacteria or yeasts – to react with the substrates (natural sugars) such as lactose in cheese, fructose in wine, and maltose in beer.
Since pre-history, people have learnt how to manage the fermentation process. For instance, evidence of a fermented alcoholic beverage made from fruit, honey, and rice unearthed in China dates to 7 000 BCE. Archaeological evidence of wine-making dating to about 6 000 BCE has been found in Georgia, south of Russia.
Around 4 000 years ago, the Egyptians discovered that they could boost the fermentation process in bread making by using rotting fruit such as dates and figs as a starter or a raising agent. The yeasts from the fruit caused a chemical reaction that softened and lightened the dough, and so leavened bread was born.
The most obvious advantage of fermented foods is that they remain edible far longer than they will in their original form. This is because the bacteria create a highly acidic environment that suppresses other microorganisms that promote the decaying process, preserving all the good stuff.
But other advantages are also apparent. Fermented food often has a more intense taste. As the fermentation process breaks down fibres, the food is easier to digest. Of course, fermented foods have always been associated with health benefits.
Throughout the world, similar techniques were developed to preserve meat, fish, fruit and vegetables. Germans and Eastern Europeans were not the only lovers of sauerkraut. In the sixth century, those who laboured on the Great Wall of China were primarily fed on cabbage fermented in wine.
The Scandanavians were not the only lovers of fermented fish – surströmming in Sweden, rakfisk in Norway – the putrid-smelling delicacy (if that’s the right word) is enjoyed in many countries around the world.
In the South West region of South Africa, before the Dutch colonised the country in the 17th century, the Khoikhoi nomadic pastoralists were known to bury large catches of fish in sand dunes for weeks. There’s no doubt that the Khoikhoi were taking advantage of the massive shoals of sardines that migrate annually along the Indian Ocean coast - the Sardine Run as it’s known today.
Burying food in pits is, of course, an obvious way to limit oxygen from the fermentation process, And it’s a technique used by many diverse cultures throughout the world.
The Polynesians who travelled vast distances in open canoes across the Pacific Ocean were sustained mainly by a dish called poi. It consisted of the roots of the taro plant, pounded into a paste and fermented in pits lined with taro or banana leaves.
In medieval England, charcoal burners often dug pits underneath their ovens to ferment the meat of deer and small game. Natural acids found in the soil would aid the process.
Throughout history, fermented foods have been the best probiotic source to support the gut microbiome. But in 1928, Alexander Flemming’s discovery of the first true antibiotic, penicillin, presented a looming, unintentional threat to the microbiome.
Considering that penicillin is reputed to have saved an estimated 80 million lives since it was introduced, it’s a tragic irony that such a threat would be posed by one of the most beneficial class of wonder drugs ever developed.
The all-American cheese and antibiotic burger
If you live in the USA and you’re a meat-eater – as 92% of Americans are – there’s some worrying news concerning your gut microbiome. The American factory farming industry is the biggest user of animal antibiotics in the world.
Some 80% of the total volume of antibiotics used in the US is added to the feedstuff and water of cattle, poultry, pigs, and sheep to minimise possible disease outbreaks and increase productivity. It’s also an activity that uses mechanisms that are, according to scientists, not fully understood.
The use of antibiotics for livestock is prohibited throughout the European Union. Also, the WHO has also called for a worldwide ban on the routine use of animal antibiotics because it poses a risk to human health in three fundamental ways.
First, overuse of antibiotics contributes to bacteria developing resistance to the drugs that doctors have routinely prescribed for generations.
Second, bacterial mutations have resulted in the growth of potentially lethal “superbugs” such as MRSA (methicillin-resistant Staphylococcus aureus), which are immune to most antibiotics. In other words, an antibiotic that used to control a type of infection by a bacterial pathogen no longer works, and the resistant strains can spread like coronaviruses, a frightening scenario.
The third risk, which has only recently been realised and is still not fully understood, affects the massive colony of microbes that inhabit the large intestine. If an antibiotic enters the colon, then, according to researchers, the overall effect is to harm the microbiome by reducing species diversity, altering your metabolism and making your body less effective in absorbing nutrients and fighting infection.
Whereas the antibiotics your doctor occasionally prescribes for an ailment will also disrupt your microbiome, it will eventually be restored. However, the continuous consumption of meat from livestock that has been routinely treated with antibiotics has severe consequences to human health.
Especially so given the quantities of meat that Americans eat. In 2020, the combined consumption figures for beef, pork, chicken, turkey and lamb was estimated at 224.63 lbs per person (101.8kgs), a record high for the US.
Look after your microbiome so it can look after you
The list of foods and beverages rich in probiotics is long and varied.
It’s no secret that among the most effective probiotics are dairy-based foods such as natural Greek yoghurt and buttermilk and unpasteurised mature cheese. Also, a fermented cow or goat’s milk-based drink called kefir that contains grains of lactic acid bacteria.
Sauerkraut, the finely shredded cabbage leaves fermented in lactic acid bacteria, is a staple in Germany, but it’s also a regular menu item in the Netherlands, Central and Eastern Europe, China, and North America.
Kimchi, the spicy dish that accompanies most meals in South Korea, mainly consists of fermented cabbage. Still, many variations (allegedly, some 180 recipes) use different vegetables as base ingredients.
Also rich in probiotics are soya bean-based foods such as miso and tempeh, an Indonesian dish popular as a meat substitute due to its high protein content.
Kombucha tea is a fermented drink made with black tea leaves, sugar, bacteria and yeast, allowing the liquid to ferment. It’s also known as mushroom tea, although it contains no fungi.
As most kinds of vinegar are fermented, any pickled vegetable, including green olives, is an excellent bet to enrich your microbiome.
It’s believed that we carry between 300 and 1 000 species of bacteria throughout the digestive tract, of which about 40 species dominate 90% of the entire colony.
Research indicates that the less diverse the species of microbes in the gut, the more prone we are to obesity, type 2 diabetes, and chronic inflammatory conditions prevalent in Western countries but virtually absent in non-industrialised societies.
A suggestion that modern lifestyle and a diet heavy on processed foods affect our microbiome’s biodiversity was born out of a fascinating research project conducted in 2008. An indigenous tribe of hunter-gatherers, the Yanomami people, who had never had contact with Westerners, were discovered in the Amazon jungle. After taking bodily samples from members of the tribe, it revealed that they had almost double the microbial diversity compared to the average American and the richest gut microbiome ever recorded.
So, living close to nature seems a healthier alternative to the lifestyle most of us lead. It’s an argument that brings me to the ‘but’ in the headline at the beginning of this newsletter.
Scanning this month’s edition of The New York Review of Books, my eye was immediately drawn to an article entitled: “What Does the Microbiome Do?” written by Jerome Groopman.
The article reviewed a newly published book entitled “Gut Feelings” written by two eminent scientists, Alessio Fasano and Susie Flaherty. These authors explored the research conducted over the last few years and weighed it up against the massive hype that gut health and probiotics have suddenly created in the media.
In a nutshell, their findings do not support many of the claims made by biotech companies promoting probiotic products.
But that’s marketing for you. It works by presenting a benefit-driven differentiator and leveraging the heck out of it. In other words – exaggerate! It’s true to say that the highly competitive world of marketing and advertising is powered by high-octane hyperbole.
For instance, manufacturers follow a generic approach, a probiotic for a ‘normal;’ microbiome. But as the authors point out, many microbiome researchers are convinced that there’s no such thing as a ‘normal’ microbiome. Not only is everyone’s microbiome different – even in identical twins – but a microbiome is a highly dynamic ecosystem that changes constantly.
As the authors state: “Because humans are not made genetically and biologically equal, we cannot generalise the use of any given probiotic formulation as beneficial to everyone’s health.”
The authors also point out that many over-the-counter probiotic preparations performed no better than placebos in various studies, and that much of the clinical research that these companies base their claims on do not pass rigorous scientific muster. For instance, a high proportion of research has been done on rodents, which may not be replicable in humans. Also, much research has been done with insufficient sample sizes.
The authors also caution against the growing trend of attributing many illnesses to bad gut health. Many other factors are being ignored, such as poverty, lack of access to nutritious food, air pollution, societal ills that influence diet and behaviour, and poor access to health care can also contribute to ill health.
Above all, the authors claim that the microbiome is highly complex and that there is far more that we don’t understand about the microbiome than we do understand.
However, there is one thing we can grasp: Impactful graphics and screaming headlines about quick cures from a bottle of “probiotic” pills should be taken with a dose of circumspection.
And if the ads make you feel anxious, try a bowl of sauerkraut with some pickles on the side. That should soothe your enteric nervous system.
My hearfelt thanks to Professor Gareth Wyn Griffiths, at the University of Oslo Institute of Biosciences for his guidance and helping me through the murky world of bugs. Diolch brawd!
Great read