With the slightest advantage often making all the difference in elite sport, the Kangaroos and Jillaroos have undergone revolutionary gut testing in a bid to find an edge.

The teams worked with Brisbane-based specialists Microba before the recent end-of-year Tests to evaluate their gastrointestinal health and see whether improving gut microbiome can boost performance.

The majority of the Australian players provided stool samples for analysis. They later received a group presentation and individual reports from Microba which included dietary suggestions based on how their gut absorbs nutrients.

Kangaroos elite performance manager Troy Thomson had been looking at gut testing for around 18 months after discussing its benefits with colleagues here and overseas.

The innovative Thomson told NRL.com the national system - encompassing the Kangaroos, Jillaroos and men's under-23s - aims to become a "research and development arm of the game".

"It's a vision that [Kangaroos coach] Mal [Meninga] has always tried to instil in all of his staff," said Thomson, who has previously incorporated other left-field training elements including virtual reality and cognitive testing.

"We try to expose the players to different experiences, modalities and methods of training and preparing that they're not necessarily used to getting in their clubs.

"The NRL clubs look after their players so well these days that trying to find something a little bit different that might help them becomes harder and harder each year."

Microba's testing showed the Kangaroos collectively lacked fibre in their diets and Thomson was able to give the information to hotel and restaurant chefs during their two-week camp to fix the issue.

The gut's effect on general physical wellbeing and mental health is established but research using mice has suggested it could increase athletic stamina.

A study from Harvard Medical School discovered the mice could run 13 percent further on average when given the Veillonella gut bacteria, which converts lactic acid into fuel for the body.

The same performance-enhancing link hasn't been proven in humans but marathon runners and endurance rowers have been found to boast significantly higher levels of Veillonella.

"There's still a lot to learn here about the gut and its impact on performance," said Dr Ken McGrath, Microba's technology liaison manager.

"They've found one [organism to improve] endurance – there might be one for strength, there might be one for recovery.

"More research is still needed to get to the point where you might be able to have a sports probiotic matched to your sport of choice to give you the performance edge."

The Kangaroos and Jillaroos' short campaigns meant the benefits of altering their diets are yet to be seen. It takes four-to-six weeks of strictly eating gut-healthy foods to notice a difference, according to Microba.

"The next part of it is to discuss with each of the players' [NRL or NRLW] clubs and their performance staff the individual results that they were able to receive," said Thomson.

"Hopefully, some of those players will make some of those changes and they will be regular ways that they prepare their meals going forward.

"So if we get [the players] again next year, hopefully they're in a better space."

A buffet lunch planned by Thomson and Microba nutritionist Christine Stewart was given to the players before the presentation to show examples of meals that are optimal for gut health.

The menu included:

Mexican beef lasagne

Baked vietnamese meatballs with rolls

Orange cranberry salmon

Nasi goreng

Roasted cauliflower, chickpeas, white bean and spiced tahini salad

Fennel, asparagus, pasta salad

Fruit salad bowls

Assorted low-fat yoghurt

Whole fruits

"We were still really conscious that it hit all the requirements from a performance perspective – so the carbs and the protein components of the meals were still there," said Thomson.

"There were just some additional grains and a few other different bits and pieces of ingredients that really helped with the fibre content of the meal."

Thomson said it was a case of adapt or fall for the Kangaroos as rival countries close the gap, evidenced by Tonga's historic win over them last Saturday.

"As soon as we stop searching for that [extra] one percent, we're going to be overtaken because the other nations are all advancing really quickly," he said.