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The microbiota and our mental health



When we think about mental health biology, our minds usually go straight to the brain. After all, this is the organ responsible for our perception, memory and control over our body.

But as studies uncover the interactions between our biological systems and the colonizing microbes, research has also uncovered links to our mental health.

The gastrointestinal tract is home to trillions of microorganisms that we call our microbiota. Image: Getty Images

The gastrointestinal tract – which runs from the mouth to the colon – contains compounds with neuroactive potential, including neurotransmitters and hormones. It is also home to trillions of microorganisms we call our microbiota that interact with almost every aspect of our physiology.

A remarkably similar neural structure to that in the brain is also hidden in the gut.

While our mouth, stomach, and intestines don’t necessarily help us think, they may be more connected to our brain and mood than you might have thought.


As the entrance to the gastrointestinal tract, our mouth is rich in microscopic life that is linked to our mental health.

In a first study of its kind, our research team recently found that oral bacteria have been linked to depression and anxiety symptoms in adolescents. These relationships can be made through our endocrine and immune systems, as oral microbiota and mental symptoms have been linked to stress hormones and markers of inflammation in saliva.

Relationships between oral bacteria and schizophrenia, bipolar disorder, and autism spectrum disorder have also been found.

But these complex relationships between mental health and oral health likely work both ways.

Our research team found that oral bacteria are linked to depression and anxiety symptoms in teenagers. Image: Getty Images

Young people with depression and anxiety may experience poorer oral hygiene, as some people with a mental disorder have more difficulty maintaining their toothbrushing routines and making regular dental appointments.

Poor oral hygiene can also lead to changes in oral microbial communities and periodontal disease (such as gingivitis), which have been linked to the subsequent development of depression.

And since the mouth is the entrance for our food to travel into the body, could diet play a role in the relationship between mental health and the oral microbiota?


Symptoms of depression can lead to an over-consumption of sugary foods and beverages, which can negatively affect oral health, while regular consumption of fruits and vegetables is associated with fewer symptoms of depression.

Leafy green vegetables have also been suggested as potential prebiotics that increase levels of nitrate-reducing and oral health-related bacteria in the mouth, including Neisseria and Rothia. Interestingly, the levels of the Neisseria subflava bacteria are lower in people with schizophrenia and mania.

Stress-induced eating has also been linked to increased unhealthy food intake, which can harm not only our physical health and oral microbiota, but also our mental health.

Common symptoms of anxiety and depression – such as changes in appetite, low energy levels, and physical symptoms – can affect a person’s desire or motivation to cook healthily. And while the relationship between diagnosed anxiety and depression and nutritional quality is less clear, sticking to a healthy diet with minimally processed whole foods seems to protect against the risk of depressive symptoms over time.

Leafy green vegetables have also been suggested as possible prebiotics. Image: Getty Images

This knowledge is valuable given the overall poor nutritional quality in Australia and underscores the continuing need for educational programs that promote healthy cooking at home. Population-based interventions to address food insecurity are also vital and could improve access to healthy food for more vulnerable members of our community.

While most of our food is digested by the time it reaches the colon, the nutrients we cannot digest – like complex plant fibers – provide an important source of energy for the gut microbiota lower down in our gastrointestinal tract.

Healthier foods support different microbes and metabolic functions than unhealthy foods. For example, fermentation of complex carbohydrates by bacteria produces short-chain fatty acids, which while playing an important role in our systemic health, also lower the pH of the colon.


A more acidic environment can limit the growth of pH-sensitive pathogenic bacteria that may be linked to chronic inflammation (such as Enterobacteriaceae and Clostridia).

Our food intake therefore strongly influences the composition of the intestinal microbiota from top to bottom. Indeed, both our mental and general health.

We also know that anxiety and depression increase the risk of functional bowel disease and bowel disease, including irritable bowel syndrome (IBS), reflux, and inflammatory bowel disease, and vice versa. Stress can lead to noticeable nausea, gas, and abdominal discomfort.

Although more well-controlled studies are needed, the high rates of co-occurrence of mental health and gastrointestinal disease may be at least in part driven by our gut microbiota.

Microbial Moods by Sophia Charuhas: installation view, MENTAL: Head Inside, Science Gallery Melbourne. Image: Alan Weedon

Anxiety and depression, co-occurring with irritable bowel syndrome, have been linked to decreased microbial diversity and increased incidence of potentially inflammatory bacteria, including proteobacteria and prevotella.

Unfortunately, current evidence suggests that just taking over-the-counter probiotics to transform our microbiota and improve our mental health isn’t that easy – at least not yet. “Designer probiotics” are touted for fighting infections, modulating the immune system and, in the future, even fighting the pathophysiology of diseases, although we are still a few years away from this reality.

Commercial diet supplements fail to take into account that our microbes can vary widely from person to person (including those we may be lacking).


If we can personalize future treatments, promising probiotics need to be carefully studied in the context of whole body health, including mental wellbeing, and we need to better understand their interactions with our non-bacterial microbes – such as viruses, fungi and archaea.

For now, a healthy diet and evidence-based psychological treatments remain the best interventions for our microbes and our minds.

But exciting things are also happening in technology.

Maybe soon we will be able to monitor our health every time we go to the bathroom. A prototype of an “intelligent toilet” developed by scientists at Stanford University monitors urine markers and our bowel movements.

A healthy diet and evidence-based psychological treatments remain the best interventions for our microbes and our minds. Image: Shutterstock

There may also soon be smart health mirrors and toothbrushes that incorporate mood and lifestyle monitoring through our smartphones.

While more research needs to be done, our “gut feeling” is not just metaphorical.

The Human Microbiome Project and other major epidemiological studies have made tremendous strides in documenting the relationships between our microbial communities and our health. Meanwhile, our studies, including the Bugs and Brains Study and the Victorian Oral Microbiome Study, are working to document the links between our microbiota and mental health here in Australia.

Understanding these complex interactions between our mood, our gut, and our microbiota will help us better understand the complexities of our mental health.

Part exhibition, part experiment – MENTAL is an inviting place to counter social prejudices and stereotypes about mental health. It features 21 works by local and international artists and research staff exploring different ways of being, surviving, and connecting with one another. Opening in July 2021, book your free tickets now.

Banner: Microbial Mood by Sophia Charuhas: installation view, MENTAL: Head Inside, Science Gallery Melbourne / Image: Alan Weedon

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Two-hour glucose tolerance test helps identify patients at heightened risk of cognitive decline



Diabetes is a risk factor for cognitive decline. In a study by the University of Turku and the Finnish Institute for Health and Welfare, researchers observed that even a higher two-hour glucose level in the glucose tolerance test predicts poorer performance in a test measuring episodic memory after ten years. Episodic memory decline is one of the first symptoms of Alzheimer’s disease.

Diabetes is known to be an independent risk factor for memory impairment. Previous studies have shown that risk factors for diabetes such as obesity, metabolic syndrome, and decreased insulin sensitivity are linked to a decrease in cognitive function and an increased risk of developing memory disorders. Fasting blood sugar is not as good a risk measurement tool as this, and according to an earlier report from the Finnish Health 2000 study, it did not predict a decline in memory functions.

The two-hour glucose test in a glucose tolerance test is a commonly used test in healthcare that assesses whether the person being tested has diabetes or impaired glucose tolerance. By definition, a person has impaired glucose tolerance when glucose levels are elevated on the two-hour glucose tolerance test but the diagnostic criteria for diabetes are not met.

In the new study, the researchers investigated whether the glucose levels of the two-hour glucose tolerance test after a ten-year follow-up period are related to cognitive functions. The surveys were carried out in the years 2000-2002 and 2011 with a total of 961 participants. Memory and other cognitive functions were measured using three tests commonly used in the diagnosis and follow-up of patients with memory impairment.

The study suggested that higher blood sugar levels measured in a glucose tolerance test in 2001-2002 was linked to weaker performance in a 2011 memory test, in which participants had a delay in retrieving a previously learned word list.

The glucose level measured in the two-hour glucose tolerance test was also associated with a greater decrease in test results during the follow-up period. The analyzes took into account the most important known risk factors for memory disorders such as age, educational background, elevated blood pressure, elevated cholesterol levels, obesity, type 2 diabetes and smoking. “

Sini Toppala, first author, Turku PhD University

The study is based on the population-based survey “Health 2000” of the Finnish Institute for Health and Social Affairs and its supplementary data, which were collected in 2001-2002, as well as on its follow-up study, the study “Health 2011”. In the first survey, the participants were 45-74 years old (mean 55.6 years).

The study shows that the glucose tolerance test helps identify patients with impaired glucose tolerance who are at increased risk of cognitive decline. This is important for targeted interventions, explains Toppala.

The research article was published as an online ahead-of-print version on August 15, 2021. The study will be published in a future issue of Diabetes Care.


Journal reference:

Toppala, S., et al. (2021) Oral Glucose Tolerance Test Predicts Episodic Memory Loss: A 10-Year Population-Based Follow-Up Study. Diabetes treatment.

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John Whaite health: Bake Off star’s eating disorder has been ‘very difficult to overcome’



The star baker, who became the 2012 Bake Off Champion, stunned Paul Hollywood and then judged Mary Berry on his culinary skills, but behind closed doors the star has struggled with his body image since he was a teenager. The star previously discussed his “serious” mental battle with depression, but when he appeared on Steph’s Packed Lunch on Channel 4, he wanted to raise awareness about eating disorders too.

The 32-year-old spoke openly about his struggles with bulimia in the hope that others would also speak out.

He said, “My body image growing up was very difficult … I was so aware that I was fat. But one thing that I was aware of as problematic for 12, 14 years was overeating and then cleaning. The painful pressing down on food and then the immediate need to get that out of me.

“If I bake a lot of muffins and something went wrong that day or time in my life, I would sit and eat all 12 muffins and then run to the bathroom and I would get sick.”

It is estimated that around one million people in the UK have an eating disorder, one in four of whom are men.

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Bulimia nervosa is an eating disorder that is characterized by binge eating followed by purification, which may include vomiting, taking laxatives, fasting, or excessive exercise.

The chef, who is still struggling with his condition, said, “One of the things that I find myself very embarrassed about is that … my food every now and then makes me feel very guilty. But it’s not something that I can control.

“I’ve only really accepted it as an eating disorder for the past 18 months, two years, and it has been very, very raw.”

The feelings of guilt that the cook feels unnecessarily about his condition are underlined by his chosen career path.


“It was very, very difficult to overcome and I think that’s because of the stigma of an eating disorder,” added John.

“Especially as a chef, I didn’t really want to talk about it because I felt like it undermined my entire career.

“How can a chef who writes recipe books and cooks on TV, how can he realistically have bulimia?”

When John first noticed the symptoms, he didn’t realize it was a major problem. Instead, I thought it was a way to deal with overeating. However, if people have the condition for a long time, it can become life-threatening.

The NHS lists several health risks that can arise from persistent vomiting or excessive laxative use.

Possible complications are:

  • feeling tired and weak
  • Dental problems – caused by stomach acid when vomiting persists, can damage tooth enamel
  • Bad breath, sore throat or even tears in the lining of the throat – also caused by stomach acid
  • Irregular or absent periods
  • Dry skin and hair
  • Brittle fingernails
  • Swollen glands
  • Seizures and muscle cramps
  • Heart, kidney, or bowel problems, including permanent constipation
  • Bone Problems – You are more likely to develop problems like osteoporosis, especially if you’ve had symptoms of both bulimia and anorexia.

Before an eating disorder turns into a life-threatening condition, there are general warning signs to look out for in yourself, as well as close friends and relatives.

These can be emotional and behavioral as well as physical in nature.

Emotional and behavioral warning signs include things like unusual swelling of the cheeks or jaw area, hiding or stealing food, excessive use of mouthwash, mints, or chewing gum, extreme mood swings.

Physical symptoms include fainting, muscle weakness, noticeable fluctuations in weight, and difficulty concentrating.

Treatment of the condition is often offered in the form of a guided self-help program. It involves working with a healthcare professional such as a therapist who will enable you to overcome the condition and understand why you are having this behavior.

You can trust an eating disorders charity advisor by calling the adult hotline 0808 801 0677 or the youth hotline 0808 801 0711.

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University of Utah study examines link between suicide risk, genetics | News, Sports, Jobs



KERA WILLIAMS, special about the standard examiner

A candle is held during the candlelight vigil for World Suicide Prevention Day at Mount Ogden Park in Ogden on Thursday, September 10, 2015.

SALT LAKE CITY – People who suffer from bipolar disorder and are genetically predisposed to post-traumatic stress disorder may have a higher risk of dying of suicide, according to a study conducted by researchers at the University of Utah.

The study looked at risk factors for completing suicide, not just attempting suicide, said Dr. Eric Monson, lead study author and co-chief physician in the Department of Psychiatry at the University of Utah, who suggested the results could lead to better screening measures to identify and identify those with previous trauma in people diagnosed with bipolar disorder the highest risk of suicide.

“Death rates from suicide are 10 to 30 times higher in people with bipolar disorder than in the general population. The suicide rate in Utah is about 22 per 100,000, or about 660 a year, “Monson said. “We found in this study that a combination of previous trauma, a genetic predisposition to PTSD, and a diagnosis of bipolar disorder can increase a higher risk of death from suicide.”

Monson said the results showed that 50% of those studied with bipolar disorder died of suicide without ever trying.

“The focus group was bipolar, but within that disorder we wanted to see if there were other factors like PTSD and severe anxiety,” said Monson. “Those with past trauma and great anxiety were much more likely to die of suicide than the other groups we studied. This is not entirely surprising, as anxiety is pretty closely linked to PTSD. “

The research team, which included Monson, U of U psychiatry professor Hilary Coon, and Virginia Willour, a University of Iowa psychiatry professor, used several thousand DNA samples from Utahners who died from suicide, along with electronic medical records. They also used data from the National Institute of Mental Health Genetics Initiative. Hundreds of people who died were diagnosed with bipolar disorder and had a higher rate of PTSD diagnoses.

According to, PTSD is a mental illness that some people develop after experiencing or experiencing a traumatic event such as an accident, sexual assault, fight, or natural disaster. These events can cause flashbacks, nightmares, or triggers. Anyone can develop PTSD, but a number of factors play a role, such as whether the traumatic event was long-lasting. In the United States, it is estimated that about seven or eight in 100 people will develop PTSD at some point in their life. Approximately 8 million adults have PTSD during any given year. About 10% of women and 4% of men develop the disorder.

“People with PTSD tend to have more severe illnesses than other people and are harder to treat with medication,” said Monson.

The study showed some promising results, Monson said, but the problem still exists of helping people who are suicidal. His own sister took her own life when she was 15 and Monson was only 7. He also lost three coworkers to suicide.

“That was an important aspect of my life that drove me to keep digging. Suicide is very complex and there are undoubtedly other characteristics such as environmental factors, toxins and chronic stress, ”he said. “There’s also decent evidence that altitude can play a role. If you look at a map, you can see that the suicide belt is in the Rocky Mountains. These include Utah, Nevada, Wyoming, Colorado, and Idaho. When you are at a higher altitude, your oxygen levels are lower and this can affect the neurotransmitters in the brain. “

Monson also said that while the study is important, it doesn’t mean that a person will definitely commit suicide – and he added that suicide is preventable.

“We have limited mental health resources, but suicide is inherently preventable and we should take all measures to help those at risk,” Monson said. “I think it’s important now that we in the medical field ask people more about serious traumatic experiences in their lives, but it’s also important that people be direct when they suspect someone might be trying to commit suicide . There is a difference between saying, “Do you feel like you might be hurt” and “Do you have the thought of killing yourself”. Please be as straightforward as possible. “

But when all you’re doing to help someone fails, the important thing is not to blame yourself, Monson said.

“It’s not your fault. It’s never so easy to think that you said something or couldn’t have said something,” he said. “Please don’t get caught up in self-blame.”

What to look out for

September is Suicide Awareness Month. Here are the warning signs when someone thinks of suicide:

  • Increased isolation from the world.
  • Bringing matters in order.
  • Give things away.
  • Anxious, tired, or depressed behavior.
  • Talk about being a burden on others.
  • Feeling hopeless or feeling like they are no use.
  • Speaking of wanting to die.
  • Display of extreme mood swings.
  • Increase in the consumption of alcohol or drugs.
  • Anger or recklessness.

Other resources:

  • National Lifeline for Suicide Prevention, 1-800-273-8255


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