Like everyone, we here at The Glow had a lot of questions about how this part of the body works and how we should be looking after it. Instead of relying on our gut feelings (ha, ha) we consulted Dr Vincent Ho, clinical academic gastroenterologist to the University of Western Sydney‘s School of Medicine.
1. What is the difference between prebiotics and probiotics?
The words prebiotic and probiotic might be enough to make your eyes glaze over, but knowing the difference between the two is an important part of understanding how your gut works.
“Prebiotics are selectively fermented ingredients that allow specific changes to the gastrointestinal microbial ecosystem that confer health benefits,” Dr Ho explains. They occur naturally in leeks, asparagus, wheat, oats and soybeans, among other foods.
Probiotics, found in foods like live-cultured yoghurt (more on that in a moment) are living microorganisms.
The main difference lies in how they behave when ingested. Dr Ho says prebiotics reach the colon, or large intestine, unaffected by digestion, while probiotics reach it in an active state and are able to “exert health effects.”
Watch gastroentologist Dr Frank Jackson discussing the difference between probiotics and prebiotics here. Post continues below.
2. So, yoghurt. What does it actually do?
Ah, yoghurt: the great equaliser. As those cutesy animated ads love to tell us, yoghurt is rich in probiotics and prompts the growth of ‘healthy bacteria’ in the gut.
“Yoghurt is a coagulated milk product that results from the fermentation of lactic acid in milk by bacteria such as Lactobacillus. Yoghurt contains large quantities of live bacteria at the time of manufacture,” Dr Ho explains.
As you might have guessed, this has some benefits. Dietician Harriet Nobbs told The Glow the healthy bacteria prompted by probiotics “helps with immune function, digestion and in the production of some essential vitamins.”
Dr Ho says the gastrointestinal benefits of yoghurt are believed to work in a few ways. “One mechanism involves the bacteria in yoghurt latching onto the delicate lining of the gut, thereby preventing harmful microbes from accessing the gut. This good bacterium in yoghurt can also interact with the mucosal lymphoid tissue in the gut and enhance its immune function,” he says.
“Finally, depending upon the type of bacterial strain, yoghurt can shorten transit time through the gut.”
Don’t feel the need to hoof down huge amounts of the stuff, though. As ABC News reports, although yoghurt has plenty of benefits you should make sure you have less than 15g of sugar in your serving, as sugar will actually feed the bad bugs in your gut. (Post continues after gallery.)
3. How does gut health affect your overall health?
First things first: while ‘gut health’ is a common term, Dr Ho says it’s an imprecise one that lacks a clear scientific definition.
Borrowing from the World Health Organisation’s definition of health, he suggests ‘gut health’ is a condition of: “physical and mental well-being in the absence of gastrointestinal complaints that require the consultation of a doctor, in the absence of any specific indications or risks for bowel disease and in the absence of any demonstrated bowel disease.”
Now we’ve covered that, how does this play into general health?
Dr Ho says disturbances to the gastrointestinal barrier — which allows nutrients to cross from the gut into the bloodstream, while preventing harmful molecules and organisms from doing so — have been shown to lead to disease. This is particularly true for gut diseases like coeliac disease and IBS.
“Changes to the gastrointestinal barrier which increase the exposure of harmful microbes and environmental toxins to the bloodstream is believed to play a strong role in the development of many autoimmune and allergic diseases,” he adds.
Another component that aids gut function is the gut microbiome — i.e. the intestinal microbial ecosystem, which contains “tens of trillions” of gut bacteria. “There is emerging evidence to link the altered gut microbiome to conditions such as irritable bowel syndrome and obesity,” Dr Ho says.
To maintain healthy gut function, we should be avoiding situations that could alter the microbiome and the mucosal immune system — these include stress and an unbalanced diet.
Watch: A green smoothie recipe that’ll help you up your leafy green count. (Post continues after video.)
4. How often are you supposed to, um, go to the toilet?
You know you’re getting comfortable with someone when you’re prepared to talk about bowel movements. We’re all friends here, so let’s get down to business.
Like many things, the ‘usual’ frequency of bowel movements varies widely from one person to the next. This is largely influenced dietary factors — Nobbs says if you have a healthy gut with lots of healthy bacteria, your digestion will be more efficient — but age also plays a role.
“For adults, anything in the range of three times a day to once every three days would be considered normal by most gastroenterologists, as long as the faeces is neither too hard nor too loose,” Dr Ho explains. That said, some people who are perfectly healthy fall outside this range and if this has been a longstanding pattern there’s no need for concern.
“Distinct changes in the frequency of bowel movements may be quite important particularly as people get older (over the age of 50) or in the background of certain risk factors, such as a strong family history of bowel cancer. In such cases further investigation is likely to be required,” he adds.
5. Does your gut have any impact on your skin?
If you are what you eat, then is the secret to a flawless complexion stored in your tummy? Well, potentially - but it's complicated.
"The gut-skin connection is best recognised through the association of many skin disorders with abnormal gut function," Dr Ho explains. There's research to illustrate this. A 2013 study found the prevalence of small intestinal bacterial overgrowth was greater among patients with rosacea; almost half of whom found it cleared or improved when they were treated with a gut-selective antibiotic.
Dr Ho adds that a number of studies indicate probiotic supplements can improve atopic dermatitis. However, he says, the mechanisms for how the gut and skin communicate are not well understood.
"While we know that probiotics can improve atopic dermatitis, no one really knows for certain whether this is due to increasing or decreasing inflammation affecting the entire body (systemic inflammation)," he explains.
What would you like to know about gut function?