The bacteria in our gut can wage war on disease and fight for our health, so it’s crucial to keep this tiny army strong with the right food and lifestyle choices. Dietitian Clarice Hebblethwaite tells how.
Each of us is home to about 100 trillion bacteria — and most of them live in the gut. Though we’re very familiar with the ‘bad’ bacteria that can cause illness, we also need to know about probiotics, the friendly ‘good’ bacteria that help keep us well. Scientists are starting to realise how crucial both types of bacteria are to our long-term health, and it’s time we did, too.
Early last century, around the same time as the famous Scottish bacteriologist Alexander Fleming discovered that antibiotics can wipe out ‘bad’ bacteria, a Russian biologist was investigating the ‘good’ variety. In 1906, Dr Ilya (Élie) Metchnikoff was studying a population in Bulgaria. He was curious about why they were in such great health and living for so long (many of the residents were over 100 years old!). After speculating that unfriendly gut bacteria aggravates the ageing process, Metchnikoff noted that the Bulgarians regularly ate a particular yoghurt. He believed that this food’s bacterial culture acidified the gut, thereby making it inhospitable to ‘bad’ bacteria. This yoghurt seemed to be key to the Bulgarians’ lifelong health.
Aside from its spawning the modern probiotic drinks and yoghurt industries, Metchnikoff’s theory went unappreciated by the wider scientific community for decades. In the intervening years, most doctors and scientists believed that our body’s bacteria were simply ‘along for the ride’ and not up to much.
It was only during the 1990s that Metchnikoff’s hypothesis — that ‘bad’ bacteria play a key role in ageing and age-related conditions — began to attract more attention. Now a major US initiative, the Human Microbiome Project (HMP), is mapping each individual bacterium, including where it lives in and on the body, to determine its role in human health and disease.
The pioneering scientists who are studying the body’s colony of microbes, or bacteria — the microbiome — acknowledge that there’s a lot they don’t yet know. But ever since the HMP began (seven years ago), they’ve been piecing this puzzle together.
The implication is that these microbes (which live on our skin and in our hair, nose, mouth and intestines) have a huge impact on our health and wellbeing, just as our genetic make-up does. And though we can’t change our inherited genes, we can change our personal microbiome — for better and for worse. The health of our gut relies on our eating the right foods, for starters.
What is the microbiome?
Your body is host to 10 microbes for each one of its cells. Most of these bacterial species live in the digestive tract, and altogether, they weigh about 3kg. Our balance of ‘good’ and ‘bad’ bacteria is as unique to us as our DNA, and these microorganisms, or microbiota, are collectively called the microbiome.
When this population of bacteria thrives, the microbiome stays strong and keeps us well. In fact, its health can affect not only our immunity, but also chronic conditions that seem unrelated to bacteria, such as obesity and diabetes. Thanks to cutting-edge science, we’re now realising just how important it is to keep our microbiome in good shape.
What do these microbes do?
Think of your digestive system as your own personal ‘gut jungle’. Research now reveals that the richer and more diverse its bacterial bloom, the healthier and more resilient the body.
More than 1000 different strains of microbes, or bacterial cells, live in and on our bodies. In fact, we have 10 microbes for each and every one of our cells. Far from being along for a passive ride, these microbes play important roles in our overall health and well-being.
Our microbiota aid digestion, neutralise invading ‘bad’ bacteria and viruses, and help manufacture neurotransmitters such as serotonin, the so-called happy hormone.
Some of these bacterial species are instrumental in regulating our stress levels. Animal studies even suggest that some of these bacteria can influence our temperament — how anxious, relaxed or adventurous we are.
When our microbiome is out of whack, we’re more likely to fall ill, gain weight and be vulnerable to a range of chronic diseases. A change of diet can upset the balance of our microbiota, as can certain medicines, such as antibiotics and the contraceptive pill. Infection is also a culprit, whether it’s due to viruses, ‘bad’ bacteria, yeasts or parasites. We need to keep our microbiome well so it can keep us healthy.
How do healthy microbes keep us well?
Some of the revelations about our microbiome are very new and need more science to support them, but we now know something about the way our gut microbes hold sway over our long-term health.
They banish ‘bad’ microbes
Visualise the inside wall of your lower digestive tract as a kerb lined with parking spaces. All microbes compete for these spaces. The good news is that healthy microbes adhere or ‘stick’ strongly; it’s as though they have longer parking permits. Once parked, they stay busy looking after the ‘kerb’ and generally keep the neighbourhood in good condition. In addition, healthy microbes make lactic acid and fatty acids, both of which lower the pH inside the colon. And happily for us, unwanted yeasts and bacteria can’t thrive at this pH.
They directly attack infections
When you’re infected with a virus, your healthy microbes spring into action, delivering their own antibiotics to stop the virus from multiplying. They can even neutralise virus-generated toxins.
They aid digestion
Our healthy microbes can boost our body’s ability to make digestive enzymes. These better enable our system to break down particular foods, such as milk that contains lactose or food that contains starch, for our body to use as energy.
They make certain vitamins
Our food gives us many vitamins, but our healthy microbes can actually make some for us, too, boosting our levels of folic acid, biotin and vitamins C, B3 (niacin), B5 (pantothenic acid), B12 and K.
How do I look after my microbiome?
Bacteria are no longer the enemy. In fact, we now know that the antibiotics we’ve used to attack ‘bad’ bacteria can kill ‘good’ bugs, too. The food we eat also has a huge impact on the nature of our gut’s bacterial community. These bacteria are alive, so they need to feed, and the food we eat helps determine which ones thrive and which barely survive.
A lack of fibre can starve the ‘good’ bugs, so eat high-fibre foods, and include sources of both soluble and insoluble fibre. The body can’t digest insoluble fibre, so it remains in the digestive tract, where it feeds the microbes. Fibre-rich foods include vegetables, fruits, nuts, seeds and legumes (such as chickpeas, beans and lentils) as well as wholegrains (including rolled oats, brown rice, and wholegrain breads and cereals). Microbes particularly love inulin and fructo-oligosaccharides (FOS), which you’ll often find in probiotic yoghurt and infant formula.
Our ancestors ate a lot of fermented, or cultured, foods, as fermentation helps preserve food. Each society has its own traditional recipes: Koreans eat pickled vegetables, or kimchi; Germans eat sauerkraut; Turks eat kefir; the Japanese drink kombucha; and many Europeans eat yoghurt. Although there’s some evidence to show that fermented foods are good for our health as well as our own internal fermentation, scientists are still trying to work out why these foods seem to be so beneficial.
Take antibiotics only when absolutely necessary. And when you’re on a course of these drugs, consider taking daily probiotic supplements, and continue on them for a month or so afterwards. (See box above.) If you suffer a bout of gastroenteritis, take probiotics daily for about a month. And when travelling overseas, consider taking probiotics every day.
Gardening is a good way to come into contact with a wider range of microbes. And let the kids get dirty, too! Their exposure to a variety of microbes helps their immune system develop fully. Living in a super-hygienic world is one possible reason for today’s high prevalence of childhood allergies — no wonder children living on farms suffer from fewer allergies than city kids do.
No antibacterial products
Television commercials would have you believe that harmful bacteria are lurking on every household surface, and that you should attack them with antibacterial sprays and wipes. But these powerful cleaning agents kill the healthy bugs, too. And the absence of these ‘good’ microbes enables the spread of new superbugs that are resistant to antibacterial agents.
What are probiotics?
Probiotics are gut-friendly strains of bacteria or yeast. These ‘good’ bacteria fight unwanted microbes, strengthen our immune system and even produce extra nutrients. And they do all this by improving the quality and diversity of our intestinal flora — our microbiome.
Some commercial foods contain probiotics, and you can also buy probiotics as supplements. If you’d like to try these foods, be aware that some yoghurts have more probiotic bacteria than others do. Look for the words lactobacillus and bifidobacteria on food labels.
The probiotics of the future will be more like pharmaceuticals than supplements. For now, you should always check the quality of any probiotic product. A good supplement should contain a strain of friendly bacteria that’s beneficial to humans, one that studies have shown to help improve your specific health concern.
How probiotics can help you
Let these gut-friendly bacteria go to battle for your health!
Coughs, colds and winter infections
If we keep our precious microbiome healthy, it can help us ward off infection, enabling us to enjoy more illness-free days. You can start by eating more fresh vegies and grains every day.
Microbes can even influence our weight. The right balance of microbes in the colon can make them more efficient at extracting and utilising kilojoules from food there, so we may also start being able to eat more food.
When infants suffering from colic are treated with probiotics, they spend less time crying.
Experts have conducted much research into giving probiotics to breastfeeding mums and pregnant women. They’ve even looked at adding probiotics to infant formula to see whether they can treat babies’ eczema. Results have been inconsistent; however, it seems that specific strains, such as Lactobacillus rhamnosus GG, could prevent eczema in some infants. (The supplements Ethical Nutrients Eczema Shield and Clinicians Multiflora Digest contain this particular strain.)
Gastrointestinal infections and diarrhoea
Probiotics can be effective at preventing diarrhoea in people who are taking a course of antibiotics or travelling. Doctors also give them to infants admitted to hospital. Probiotics can also help ease the severe diarrhoea that results from acute infection, such as rotavirus or norovirus. If you’re taking antibiotics, try Ethical Nutrients Gastro Relief; if you have traveller’s diarrhoea, try Ethical Nutrients Travel Bug; and if you need to relieve severe infection-related diarrhoea, try Ethical Nutrients Gastro Relief or Ethical Nutrients Eczema Shield.
A change in the microbiota can have the unwelcome effect of slowing the bowel. Happily, certain strains of probiotics, such as Lactobacillus casei shirota (available in the fermented milk drink Yakult) can help relieve constipation.
Irritable bowel syndrome (IBS)
About 20 per cent of Australians have IBS, which can also develop after a bout of gastroenteritis or a ‘tummy bug’. The main symptoms of IBS are bloating and excessive (or smelly) wind. In many IBS sufferers, the microbiome is out of balance, so restoring the microbiota can help relieve uncomfortable symptoms. The probiotic strain Lactobacillus plantarum 299v (which you can find in the supplement Ethical Nutrients IBS Support) can help reduce wind and bloating.
Inflammatory bowel disease
An imbalance of microbes can worsen bowel inflammation, including chronic conditions such as Crohn’s disease and ulcerative colitis. (This finding continues to provoke much scientific debate.) In some cases, the unwanted bacteria move higher up the intestinal tract — where they shouldn’t be — and colonise the small bowel. Doctors use antibiotic and dietary treatments to ‘starve’ the bacteria, followed by a course of probiotics to reestablish healthy microbiota; however, this treatment can be expensive.
Our healthy microbiota appear to do much to protect us from the development of cancers. In a four-year Japanese study, researchers gave people a daily drink containing Lactobacillus casei shirota (the strain in the fermented milk drink Yakult). This simple treatment reduced the recurrence of atypical colonic polyps, which are often a precursor of colon cancer.
Thrush and recurring urinary tract infections
Many women are troubled by repeated thrush or urinary-tract infections. Doctors often prescribe antifungal creams or antibiotics, but these problems can sometimes become chronic and hence a major source of discomfort. It’s heartening to hear that improving microbiota without using antibiotics can reduce and eliminate these infections. Two probiotic strains that can be helpful are Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 (both of which are available in Blackmores Women’s Bio Balance).
As we discover more about the impact of our food and lifestyle choices on our gut, we’ll be able to manage our health in new and far-reaching ways. For now, it seems we could be enjoying the health benefits on the horizon sooner than we think.
The microbiome vs obesity (and other chronic conditions)
Scientific evidence now shows that obese people tend to have fewer and less diverse gut bacteria, in other words, a poor-quality microbiome. Studies suggest that having an ‘obese’ microbiome sends the body signals that encourage the storage of extra fat. Health professionals have always believed that obesity itself leads to chronic health conditions such as heart disease and diabetes — but they’re now wondering whether this lack of rich gut bacteria could be to blame. This is because researchers have also observed that even a slim person with a poor-quality microbiome can show the same warning signs of these diseases.
Establishing this link would have a massive impact on the way we treat and prevent these conditions. So a major international enterprise, the Flemish Gut Flora Project, is now underway to try to unlock this link. “We’re not there yet; now we need studies in which we can monitor people for a longer period,” says lead scientist Jeroen Raes, who is working on the project.
Faecal transplants: The next frontier
A course of antibiotics can cause the nasty and sometimes fatal bacterium Clostridium difficile to take up residence in the gut and trigger recurrent diarrhoea. One novel treatment is successfully fighting this bug with healthy faeces, which is rich in ‘good’ bacteria. Faecal transplantation involves moving a healthy person’s poo into a sick person’s gut, where it can kill the ‘bad’ bacteria. Patients can swallow gel-coated capsules or, in some instances, receive a transplant through a very fine tube that slides into the nasal passage and down to the small intestine. And this new probiotic therapy has a success rate of 90 per cent!