MEN are from Mars, women are from Venus - and their gut bacteria is just as different.
New research from Victoria University shows gut bacteria play different roles in men and women.
The study has possible implications for the current "one size fits all" approach usually used to treat digestive disorders.
"We can no longer assume that a certain type of bacteria is going to do the same job in males and females, and now need to consider that each gender may respond differently to the same treatment," said lead researcher Amy Wallis.
The study looked at gut bacteria, such as streptococcus, lactobacillus and clostridium, in chronic fatigue sufferers.
The results showed certain bacteria can behave differently in males and females, even in cases where the balance of gut bacteria looked the same between the sexes.
Ms Wallis said men with high levels of streptococcus in their gut experienced more problems, while females experienced less problems.
"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," she said.