Improving gut bacteria could help curb anxiety, according to a review of medical studies.
Probiotics and sticking to a balanced diet have both been found to have a positive effect on symptoms.
Eating more fruit and vegetables appears to be the most beneficial intervention for boosting ‘good bacteria’, scientists said.
The Chinese research is the latest in a long line of studies to link mental health to microorganisms found in the gut.
Improving gut bacteria, especially with a varied diet, could help curb anxiety, according to a review of medical studies by researchers in Shanghai
Researchers from the Shanghai Jiao Tong University School of Medicine reviewed 21 studies that looked at 1,503 people all together.
Around two thirds of them, 14, had chosen probiotics as interventions and seven chose non-probiotic ways, such as adjusting daily diets.
Probiotics are found in foods, such as kefir, yoghurt, sauerkraut, miso and pickles, and are also made into supplements with various strains.
Overall, more than half (52 per cent) of the studies, 11, showed regulating intestinal microbiota had a positive effect on anxiety symptoms.
Of the 14 studies that had used probiotics as the intervention, more than a third (36 per cent) found them to be effective in reducing anxiety symptoms.
Six of the seven studies that had used non-probiotics as interventions found those to be effective – an 86 per cent rate of effectiveness.
Some of the 21 studies had tried to improve gut bacteria while also allowing treatment as usual, such as anti-anxiety medication. But there were only reductions in anxiety symptoms with non-probiotic studies, compared with probiotic ones.
WHAT CAN YOU DO TO IMPROVE GUT BACTERIA?
- Eat a diverse range of foods that contribute to the growth of different types of bacteria. The more species of bacteria you have, the greater number of health benefits they may be able to contribute to.
- Fibrous foods are believed to improve the gut bacteria. Fruits, vegetables, beans and legumes are high in fibre. Choose wholewheat foods such as brown pasta and rice over white to get more fibre.
- Sugar, alcohol and artificial sweeteners are often advised to be cut down on to improve gut bacteria.
- Probiotics, which are live microorganisms, may benefit your health by changing the overall composition of the microbiota. They are found in a range of natural food sources, particularly fermented foods.
- Prebiotics are foods that ‘fertilise’ and feed the probiotics. They include leeks, onions, garlic, chicory, beans and cold potatoes.
The researchers believe interventions to improve gut bacteria without probiotics, ensuring a diverse range of foods, is more successful at bacteria growth.
Writing in the journal General Psychiatry, they said further trials are needed to confirm the findings.
They added: ‘There are two kinds of interventions (probiotic and non-probiotic interventions) to regulate intestinal microbiota.
‘It should be highlighted that the non-probiotic interventions were more effective than the probiotic interventions.
Within the 14 studies that use probiotics, between one and five types of probiotic were used.
The researchers said this could lead the probiotics to fight against each other to work effectively.
It may take a long time – more than the length of the studies – to significantly increase the abundance desired bacteria.
The authors acknowledge some limitations, such as differences in study design, subjects, interventions and measurements.
But they said the quality of the studies was high, and they suggest consideration of regulating gut bacteria to alleviate anxiety symptoms.
There is evidence trillions of bacteria in the gut influence parts of the brain involved in emotion by a communication path known as the ‘brain-gut axis’.
Physical and chemical connections between your gut and brain, including millions of nerves and neurons, influence the role of either ‘organ’.
The close interaction between the two can explain how digestive juices start being produced when our brain sees food or begins eating, or why we feel sick when nervous or anxious.
Most people have feelings of anxiety at points, but it is considered a mental health problem if it impacts a person’s ability to live their life.
Physically, people who suffer with anxiety regularly cope with panic attacks, sweating, teeth grinding, nausea, or dizziness.
Anxiety disorders are the most common mental illness in the US, affecting 40million adults, with a further 8.2million cases in the UK, according to charities
Does diet affect mental health?
Much scientific research into mental health focuses on the brain but some scientists believe our gut can also play an important role.
The gut microbiome, an ecosystem of organisms such as bacteria, yeasts, fungi, viruses and protozoans that live in our digestive pipes, has been linked by various studies to lots of mental health disorders, including autism, anxiety, depression and schizophrenia.
Dr Ayesha Akbar, of St Mark’s Hospital, London, explained how the microbiome ‘may well be key’ to treating mental health disorders in the future.
While this strand of treatment is currently theoretical, there are certain foods that can improve the health of the microbiome, and therefore potentially your mental well-being.
Foods that are rich in prebiotics like bananas, raw onion and Jerusalem artichokes are favourable. Meanwhile ones that are high in emulsifiers, like processed food, are best avoided as they can hinder gut health.