Gut bacteria rule our world.
The importance of having a healthy microbiota (the community of 10 to 100 trillion microorganisms in our bodies, primarily in our guts) has become a focal point for everyone from researchers to nutritionists to anyone interested in their health and wellbeing. It explains the exponential rise in popularity of probiotic (healthy bacteria) foods and supplements globally.
Does that mean you should stock up on probiotics? No.
Yes, healthy gut bacteria are incredibly important on many levels. Yes, plenty of research indicates that eating natural probiotics like kim chi or yoghurt is really good for us.
But, buying strains of probiotics because a study has suggested it has health benefits is misguided.
Researchers are still trying to understand what constitutes healthy microbiota. This is because it varies from person to person and, as a new study has found, between men and women also.
"It's a balance of bacteria and it's all about achieving that balance," says PhD student and lead researcher on a new paper Amy Wallis, of Victoria University. "But, people have a balance that is healthy for them."
Taking certain probiotics will improve one person's balance, but not necessarily the next. In fact, for this reason probiotics could cause problems.
Wallis' co author on the paper, Dr Michelle Ball adds: "We now know that a good balance of bacteria for one person may not be good for the next person, so taking a probiotic without knowing what your individual system looks like may actually do more harm than good."
In their new paper, published in the journal Scientific Reports, they found that the same balance of certain bacteria could have vastly different effects between men and women.
Taking a probiotic without knowing what your individual system looks like may actually do more harm than good.Dr Michelle Ball
High levels of Streptococcus bacteria in the gut related to more symptoms in men with Chronic Fatigue Syndrome, but less for the women.
"This and other results with Lactobacillus bacteria show that caution is needed when using probiotics as, in some cases, it could do more harm than good," Wallis added.
She suspects that the differences between the men and women result from the connection between the immune system, the hormone system and microbiota.
"Some research has shown that testosterone can increase an immune response in male rats ... can make the immune response stronger," Wallis says. "We're not sure which way it works but the hormones and bacteria affect the immune system somehow."
Where does that leave us with probiotics?
"Probiotics can be extremely beneficial," she says, noting that research into understanding the microbiota is still in "early days".
"I think we really have to be cautious about over-generalising specific research. You can't take the results of a study – that looks at males or a certain group – and then generalise to everyone.
"We don't know who exactly probiotics are benefiting."
She suggests seeking medical advice and having an assessment of your gut bacteria before assuming it's appropriate to take probiotics.
While probiotics may require a more personalised approach, there are ways we can all get to the guts of a healthy microbiota.
Far from a fart joke, excess flatulence can be a sign of a bacterial overgrowth in the small intestine from conditions such as diabetes.
A trip to the doctor may be on the cards, but a diet clean-up is a necessity for many.
Eating a poor diet, even three days a week, can change the sensitive balance of bacteria and lead to weight gain and ill health, according to a new study by the University of NSW.
"Intermittent exposure to junk food three days a week is sufficient to extensively shift the gut microbiota towards the pattern seen in obese rats consuming the diet continuously," said co-author Professor Margaret Morris.
"A reduction in the diversity of the gut's microbiota and a loss of some of the beneficial biota is clearly not a good thing for health.
"While these findings are yet to be replicated in humans, those who are strict with their diet during the week may be undoing all their good work by hitting the junk food over the weekend."
Gut health tip
Lee Holmes, author of Heal Your Gut suggests we EAT LESS CRAP: Carbonated drinks, Refined and processed sugars, Additives, artificial colours, flavours and sweeteners, Processed and packaged foods and EAT MORE REAL FOOD: Fermented food, low-fructose fruits and vegetables, Organic and unprocessed foods, Omega-3 fatty acids, Drinks such as herbal teas and filtered water.