How to keep your gut healthy
Based on the latest research, scientists have discovered that your gut has a big role to play in everything from your immune system to how hungry you are - and keeping it in good shape might even help you achieve long-term weight loss.
You’ve probably heard that your weight is determined by your genes but did you know it can also be determined by your gut? We’re talking about the system of bacteria, fungi and microbes that live within your intestines. It might seem odd that these tiny specks, invisible to the naked eye, could have anything to do with your weight, but fascinating new research has linked good gut health with lasting weight loss.
To function properly, your gut needs lots of fresh fruit, vegies and wholegrains and good bacteria
What is gut health?
Your gut is made up of your small and large intestines. Within your intestines live more than 100 trillion microbes, or bacteria, called microbiome. Our microbiomes are unique to each of us – even more personal than DNA! Humans share around 99 per cent of our DNA, but less than 10 per cent of our microbiome. To function properly, your gut needs a bit of dirt (from patting dogs or gardening, say), lots of fibre (fresh fruit, vegies and wholegrains) and good bacteria from prebiotics and probiotics.
Probiotics or prebiotics?
Probiotics are live bacteria found in foods like yoghurt, tempeh, miso and kimchi. Probiotics use prebiotics (usually types of fibre, not alive) as food sources – the more prebiotics you eat, the more your gut’s natural probiotics will flourish and thrive. While many of us think of probiotics as the pills we buy from the chemist, it’s actually best to get your fix from food (we’ll explain why a little later).
Dr Robynne Chutkan, author of The Microbiome Solution, likens microbes (bacteria) to worker bees – they perform the job of an entire ecosystem. They live within the walls of our intestines, working away to keep us healthy. They help us digest food, train our immune system to figure out threats, extract vitamins from food and aid in detoxification. When you have good gut health – a variety of diverse thriving microbes able to chew through fibre and break down nutrients – your body is better able to digest food, fight infection, absorb nutrients and eliminate waste.
Good gut health might also be the key to real, sustainable weight loss. Here’s how: those 100 trillion microbes all have jobs to do. Some of them can alter the way we store fat, how we balance glucose levels in the blood and how we respond to hormones that help us feel hungry or full. Unfortunately, our overly clean lifestyles, coupled with a highly processed diet, has stripped diversity from our microbiome and threatened our gut health. When we have the wrong mix of microbes, we’re more susceptible to weight gain, even accounting for what we eat and how much we move. Some scientists now believe that it’s our changed gut health that’s making us sick and could be causing us to gain weight.
People today are about 10% heavier than in the 80's, even if they followed the same diet and fitness plan.
Are we bigger today?
Yep, you read that right. You’ve probably heard that your genes can influence your weight, but you might not know that how healthy your gut is - or isn't - can also affect it. A 2015 study out of Toronto showed that it’s harder for adults today to maintain the same weight as adults did 20-30 years ago, even with the same levels of exercise and calorie intake. The possible reason? Poor gut health. The study found that people today are about 10 per cent heavier than in the 1980s, even if they followed the same diet and fitness plan. The authors believe that one of the factors involved is our changed microbiome. Reliance on antibacterial cleaners and hand sanitisers, increased consumption of antibiotics (both personally and through the meat we eat) and a diet low in fibre have changed our gut bacteria and made us more prone to weight gain.
Researchers at New York University have also found that microbes linked to ghrelin (a hormone that helps us tell when we are full), were once abundant in our microbiome, but now they’re rare. Martin Blaser, the head researcher, believes that our over-reliance on antibacterial cleaners has contributed.
“Antibiotics are like deforestation, they knock out everything, good and bad”
Lifestyle and Gut Health
Dr Phil Hugenholtz, a microbiologist at the University of Queensland and head of The Australian Gut Project, says we need to cut back on antibiotics and antibacterial agents. “Antibiotics are like deforestation – they knock out everything, good and bad,” he says. “Don’t get me wrong, antibiotics have saved a lot of lives, but we should only use them when we really need them – we have to be judicious. There’s a lot of evidence to show that giving kids antibiotics when they don’t really need them harms their gut bacteria for good.” And of course, he adds, there are antibiotics in much of the meat we consume, which can also wipe out good bacteria. Does he think that our clean lifestyles have made us all sick? “It’s complicated; it certainly doesn’t mean you can sit on the couch and eat chips and you won’t gain weight as long as you have a bit of dirt in your life.” But, he adds, the hygiene hypothesis – the idea that autoimmune diseases like Crohn’s, ulcerative colitis, MS, lupus and rheumatoid arthritis are far more common in developed countries, where we’re less exposed to bacteria – suggests that we have seriously compromised our gut health.
There’s certainly evidence that gut microbes differ between slim and obese populations. Studies have found slim people tend to have more diverse microbiota and more bacteroidete. While obese people have more firmicutes. This is important because they help control how many calories we absorb – more bacteroidetes means you’ll absorb fewer calories, more firmicutes leads to storing more calories. What’s more, some microbes can actually make you crave foods high in sugar, fat and salt. Researchers at UC San Francisco, Arizona State and the University of New Mexico found that microbiota that travels from the gut to the brain along the vagus nerve can influence eating. Gut flora are competitive and, in order to survive, they manipulate us into eating foods that allow particular microbes to thrive. Obese people, for example, are more likely to have gut flora that isn’t very diverse, meaning that certain bacteria have competed to take dominance.
Exercising and reducing stress are both great for your health. “Exercise releases endorphins and we believe that these can positively affect gut flora,” says Dr Muir. Stress works similarly. “Stress is a chemical reaction,” says Dr Hugenholtz. “Your brain emits cortisol when you’re stressed, which then streams through your blood to reach the gut. Your gut then reacts to the hormone and becomes stressed, too. It’s all a network.”
And of course, ditch the hand sanitiser and get comfortable with a little dirt. Dr Chutkan recommends using natural cleaners made with white vinegar and bicarb soda as household cleaners, and says one of the best things we can do is to grow a garden and eat from it.
Eating for a happy tum
The good news is that, unlike your genes, you can change your gut health. The first thing to do is eat plenty of fibre. “Look for prebiotic fibres,” says Dr Jane Muir, Head of Translational Nutrition Science at Monash University. “They contain inulin, a type of carbohydrate we can’t break down, that acts as friendly ‘food’ for our good gut bacteria. The more inulin our bacteria can feed on, the more it will flourish and multiply.” Good sources include legumes, artichokes, pulses, rye, barley, kemut, amaranth (gluten free), cashews, pistachios, watermelon, persimmons, lupin (a type of flour), onions, garlic, leeks and grapefruit. You probably know that fibre helps keep you full and helps with weight loss, but the link between gut health, fibre and weight loss isn’t as well known. A study at the University of Illinois showed that adults who ate a fibre-enriched snack bar once a day for three weeks increased their bacteroidetes and decreased their levels of fermicutes, a ratio that’s linked to having a lower BMI.
The next step in good gut health is to introduce fermented foods, which are high in probioticsthat help boost our gut flora. “Kefir, yoghurt and fermented vegetables like sauerkraut and kimchi are good sources,” says Dr Muir. Try adding kimchi to salads, or sauerkraut to a sandwich (on rye bread). When it comes to taking supplements, the jury is still out on whether or not they’re actually effective. Probiotic pills contain live bacteria, but many of the strains don’t actually make it to your gut intact (stomach acid often eats away at them, or they don’t get the oxygen they need to survive). Also, if they’re not stored properly, the bacteria can die pretty quickly (make sure yours go in the fridge immediately). Dr Hugenholtz says we’re probably better off getting our pre- and probiotic fix from a variety of foods, rather than potentially wasting money on expensive supplements.