It is a practice favoured by Lena Dunham, Tom Hanks and Lady Gaga to boost their focus and bring about calmness in an often busy, distracted world.

Now researchers have found evidence that frequent meditation over several years may help alter the human gut – boosting the body’s immune system and reducing the risk of anxiety, depression and heart disease.

In a small study of Buddhist monks, researchers found deep meditation could help regulate the gut microbiome, and lower the risk of physical and mental ill health. The findings feature in the journal General Psychiatry, which is published by the British Medical Journal.

“The microbiota enriched in monks was associated with a reduced risk of anxiety, depression and cardiovascular disease and could enhance immune function,” the researchers wrote. “Overall, these results suggest that meditation plays a positive role in psychosomatic conditions and wellbeing.”

Meditation is increasingly used to help treat substance abuse, traumatic stress, eating disorders and chronic pain. But until now it has not been clear whether it could also be able to alter the composition of the gut microbiome.

In an effort to find out, researchers led by the Shanghai Mental Health Centre at the Shanghai Jiao Tong University school of medicine analysed the stool and blood samples of 37 Tibetan Buddhist monks from three temples and 19 secular residents in the neighbouring areas.

Tibetan Buddhist meditation originates from the ancient Indian medical system known as Ayurveda, and is a form of psychological training, the researchers said. The monks in the study had practised it for at least two hours a day for between three and 30 years.

None of them had used agents that can alter the volume and diversity of gut microbes – antibiotics, probiotics, prebiotics or antifungal drugs – in the previous three months. Both groups were matched for age, blood pressure, heart rate and diet.

Stool sample analysis revealed significant differences in the diversity and volume of microbes between the monks and their neighbours.

“Bacteria enriched in the meditation group at the genus level had a positive effect on human physical and mental health,” the researchers wrote. “This altered intestinal microbiota composition could reduce the risk of anxiety and depression and improve immune function in the body.

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“Collectively, several bacteria enriched in the meditation group [have been] associated with the alleviation of mental illness, suggesting that meditation can influence certain bacteria that may have a role in mental health.”

The researchers applied an advanced analytical technique to predict which chemical processes the microbes might be influencing. This indicated that several protective anti-inflammatory pathways, in addition to metabolism were enhanced in the monks practising meditation.

The findings also indicate meditation may reduce the risk of cardiovascular disease, the researchers said.

Blood sample analysis revealed levels of agents associated with a heightened risk of cardiovascular disease were significantly lower in the monks than in their secular neighbours.

The researchers cautioned that the study was observational and the number participating was small, all male and living at high altitude, making it difficult to draw any firm or general conclusions. The potential health implications could only be inferred from previously published research, they added.

However, based on their findings, the researchers said the role of meditation in helping to prevent or treat mental and physical illness merited further research.

“These results suggest that long-term deep meditation may have a beneficial effect on gut microbiota, enabling the body to maintain an optimal state of health,” the team concluded.

Earlier this month, Hanks, 66, revealed how he had the comedian Jerry Seinfeld to thank for his love of meditation. The two-time Academy award-winning actor told NBC’s Today show how Seinfeld, 68, had first recommended the practice to him.

“I said, ‘Oh, I’ve been working. I’m taking a year off [because] I’m just really tired. I’ve been working like six years,’” Hanks recalled before Seinfeld, 68, suggested meditation.

“He goes, ‘No, you’ve got to. I’ve been doing it since college. He put me together with his teacher, and it’s an odd, easy, life-changing thing.

“And should everybody do it [meditate]? Sure, why not?” Hanks added.