Pushing back dinner time when we work late doesn't just disrupt our bodies, but the millions of bugs that live within us and help make us who we are.

New Zealand scientists have explored how our gut microbiota – which play a role in everything from immunity and obesity to mental health – are also affected when we eat out of step with our natural internal clock.

This clock, also known as our circadian rhythm, is designed to regulate sleep and wakefulness, and can be influenced by cues such as when we eat.

When we change these cues – by eating later, or badly – we disturb the rhythms of our gut microbes, along with their functions in breaking down food and generating energy.

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This upset might also partly contribute to increased risks of obesity, diabetes and metabolic syndrome.

The researchers found that, by eating fibre-rich foods at the right time, we could control the harmful effects of poor sleep.

"Delays in evening meals or bedtime are increasingly common due to lifestyle choices, long work hours, shift work, or frequent travel in different time zones," Plant & Food Research scientist Dr Shanthi said.

"Manipulating the microbiota is a promising strategy to restore our body's circadian rhythm and state of equilibrium."

Thinking about what and when we eat might provide natural strategies to modulate our microbiota, said Shanthi, who carried out the study with colleagues from the University of Auckland and the University of Amsterdam.

"Plant foods such as wholegrains, fruits and vegetables are a rich source of fibre and polyphenols that are important sources of nutrients for our gut microbiota."

Plant & Food Research scientists work with a range of foods - including berries, cherries, kiwifruit, leafy greens and cereals - that support the growth of favourable bacteria in the gut.

These foods not only played a role in maintaining gut health and protecting against pathogens, but also resynchronising our body clocks.

Parkar's work was investigating the impact of consuming these nutritious foods during the day and limiting food intake before bedtime, as restricted feeding had been shown to help restore circadian rhythms.

Another new study co-authored by Plant and Food Research scientists discovered the first gut bacterium specialising in breaking down a hard-to-digest substance found in plants.

Remarkably, their findings suggest that the human gut microbiome was evolving to accommodate Kiwis' consumption of fibre-rich foods.

The presence of the bacterium, called M. pectinilyticus, positively correlated to the participants' consumption of pectin, a dietary fibre that makes up 40 per cent of the plant cell wall in common fruits and vegetables such as kiwifruit and tomato.

The more fibre one eats, the study found, the more likely it was that this beneficial microorganism was present.

Conversely, other recent research co-authored by Kiwi scientists found a diet high in fat was linked to unfavourable changes in the type and numbers of gut bacteria, along with a rise in inflammatory triggers in the body.

Five ways to love your bugs

• Eat plenty of high-fibre foods such as legumes, beans, peas, oats, bananas, berries, asparagus and leeks.
• Eat a diversity of healthy foods. A wider range of foods nurtures bacterial diversity.
• Avoid fatty foods and artificial sweeteners.
• Probiotics, prebiotics and fermented foods can have limited benefits, a better, healthier diet is key.
• Improve your lifestyle: more sleep, more activity, lower stress helps your microbiome as well.