It’s arguably the most important health discovery in recent times — our gut bacteria are a barometer of our current and future wellbeing. When they’re not well, our health suffers too. Dietitian Katrina Pace explains.
What are gut bacteria?
It’s the bacteria, viruses, yeasts and fungi that live in our digestive system. Together, they are called the ‘gut microbiota’. They help to keep our intestine lining healthy and absorb nutrients from our food.
Gut bacteria make vitamins that support our body functions, and help our body make enzymes, neurotransmitters and hormones. Different types of gut bacteria do different things: some help to reduce inflammation, some help to digest and metabolise nutrients, while others help regulate the genes that trigger disease. No wonder they’re attracting so much attention!
Once it was thought we had no bacteria until we were born, but recent studies have shown that bacteria and viruses can be transferred during pregnancy. And by the age of about three years old, we have a fully developed range of gut bacteria.
Risk of disease
Emerging research shows the variety of gut bacteria we have can influence whether or not we develop eczema, hay fever, asthma or food allergies. And as we get older, the health of our gut bacteria could influence our risk of getting diabetes, heart disease, irritable bowel syndrome, liver disease or depression.
Can gut bacteria play a role in our mental health?
Yes, our body relies on gut bacteria to produce serotonin — a neurotransmitter that helps stabilise our mood and emotions. And some antidepressants work by keeping this serotonin in our body longer. The links between gut bacteria and mental health is a new and exciting area of research.
Can’t sleep? Are your tummy bugs to blame?
Hormones help keep our body clocks ticking. And it now looks as if our gut bacteria, in turn, keep these hormones regular. But beware that any changes to your body clock through jet lag, missing meals or going on fasting diets can change the composition of your gut bacteria.
The link between stress, gut bacteria and food intolerances
Irritable bowel syndrome (IBS) is a way that our gut bacteria tell us they’re not happy. One of the main symptoms of IBS is tummy pain. Stress, and particularly long-term stress, increases pain around the tummy area (called ‘visceral sensitivity’). Recent research shows that both short- and long-term stress can also damage the makeup of your gut.
Two of the most successful treatments for IBS are stress management and a low-FODMAP diet. FODMAP is an acronym for a group of carbohydrates: Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. FODMAPs are poorly digested by some people. Carbs are actually the main food source for gut bacteria, but FODMAP carbs feed the bacteria that are growing out of balance and causing problems. However, different bacteria eat different foods, so with a low-FODMAP diet, other gut bacteria are given a chance to grow back and flourish. This is why, over time, FODMAP foods can be gradually and successfully reintroduced.
Studies have found that around 75 per cent of IBS patients had fewer symptoms while on a low-FODMAP diet. One study showed evidence that the low-FODMAP diet increased the richness and diversity of one type of bacterium. Another study, which followed people over 18 months, found most had successfully reintroduced FODMAP foods.
Exercise gives gut bacteria a real workout
We all know that regular exercise is important for keeping us both physically and mentally well, but emerging research suggests that exercise can also affect our gut bacteria. In a study comparing members of a rugby team to a less active group of men, a wider range of gut bacteria (which is a good thing) was seen in the rugby players, even after dietary differences were accounted for.
Studies on active mice also showed a larger range of gut bacteria compared to a group of more sedentary animals. This connection between gut bacteria and exercise is so new that we are not exactly sure how it works.
It could be a combination of increased speed of movements through the gut, reduced stress and anxiety, and weight loss — all things that keep your gut healthy.
Gut health quiz
Q. How can fermented foods help me (and my gut) feel better?
A. Fermented foods like sauerkraut, kimchi, kombucha and yoghurt contain vast amounts of bacteria. Some are also been known to have healing properties. The bacteria in fermented foods can help good bacteria in our gut grow.
Q. Is eating whole grains bad for my gut (and my health)?
A. Whole grains contain fibre and carbs — the favourite food of good gut bacteria. Studies show that eating whole grains and other fibre helps us grow the best mix of gut bacteria. However, if you have a bad mix of gut bacteria and a lot of tummy problems such as bloating, try a low-FODMAP diet which temporarily restricts some grains such as wheat and bran. But before cutting out entire food groups, talk to a dietitian who specialises in IBS.
Q. Are windy foods like beans and lentils bad for my gut?
A. No — quite the opposite. Beans and lentils contain important fibres that are a great food source for healthy bacteria. But be careful. It’s best to introduce any new food for bacteria slowly. If you don’t normally include beans and lentils in your diet, start with 1–2 tablespoons every 2–3 days, and build up slowly from there. Got tummy problems already? Some beans and lentils may actually be the cause of your problems if you have an intolerance to certain FODMAP foods. But there are alternatives, such as canned or cooked lentils. Most of the offending FODMAPs leach from the lentils when cooked, so just drain and rinse off the liquid.
The three Ps to keeping your gut bacteria happy
Minimise the stress in your life. Stress and anxiety are bad for our gut bacteria.
Set aside time every day to do at least 30 minutes of moderate activity, like going on a brisk walk or swimming laps at the pool.
Be aware of what’s going on around you and accept it for what it is. Identify what are helpful thoughts and what are not.
Ask for a hand. Sometimes, having more peace needs the support and assistance of others. Don’t be afraid to ask for help.
Less PROCESSED food
A diet full of takeaway and packaged foods that are high in processed fats and sugars and low in fibre will lead to a lower diversity of gut bacteria and the overproduction of bad bacteria that can cause inflammation.
Enjoy high-fibre whole foods such as fruit, vegies, whole grains, beans and lentils.
Daily PROBIOTICS and PREBIOTICS
Probiotics are live bacteria that can help to increase both the number and types of good bacteria that live in our gut. Prebiotics are foods that feed our bacteria.
We can get our daily intake of probiotics by eating fermented foods, such as kimchi, sauerkraut, kombucha, or probiotic-rich plain yoghurt. Start off slowly and gradually increase the amount over 1–2 weeks.
Feed your gut bacteria with their favourite foods — prebiotic-rich carbohydrates, and include them in your diet every day. But we’re not talking carbs like white bread and cake. Think wholegrain and high-fibre carbs, such as lentils, grainy bread and firm bananas.
Here are some of the recent findings on gut bacteria’s effects on the body.
US researchers working with laboratory mice have found that gut bacteria could trigger metabolic changes that influence the development of cancer.
A UK study analysing over 1000 sets of twins has identified gut organisms that influence metabolism, and even food preferences. By studying twins, researchers are finding that these can be inherited through our genes.
Stress is also being linked to gut bacteria. Not only does stress make changes to our gut bacteria, but these bacteria also impact our behaviour and mood. In fact, the temperament of children as young as 18-months-old has been connected to the diversity and abundance of their gut bacteria.
Antibiotics, like amoxicillin (Amoxil), have been shown to reduce the variety of bacteria in the gut. And researchers found that people who ate white bread also have less diverse gut bacteria.
Ditch the hand sanitiser?
We know antibiotics damage both good and bad bacteria in our gut. Further, antibacterial products affect the bacteria in our mouths and on our skin.
Having the right bacteria in our mouths creates a ‘biofilm’ that acts to protect our teeth against the acid from the foods we eat. The wrong balance of bacteria, however, is damaging to our teeth.
Similarly, over-using antibacterial hand sanitisers can actually damage your skin and help bad bacteria to grow. It may explain the increase in resistant strains of bad bacteria.