Mental Health 5 MIN READ

Decoding New Research: Your Gut Can Tell How Lonely You Are

The gut is usually associated with eating and digestion. We’ve all heard of the phrase ‘feeling gutted’, but new research suggests that there may be more than just metaphorical truth to this.

Written by Alina Gufran

Jan 05, 2022
decoding new cover


The gut is usually associated with eating and digestion. We’ve all heard of the phrase ‘feeling gutted’, but new research suggests that there may be more than just metaphorical truth to this. In recent studies, scientists have found evidence that the gut microbiome is not just important for physical and digestive functioning but also has an important link with loneliness, ‘wisdom’ and mental health. In particular, one study carried out by researchers at the University of California, San Diego, has found evidence to show that both loneliness and wisdom (or compassion), are related to gut microbial diversity and composition (1).

Gut health and loneliness

The gut microbiome or gut flora refers to the many millions of bacteria, fungi and other microbes that live in our digestive tracts. Most of what we know about how the gut influences a person comes from animal studies. Earlier research has demonstrated that gut microbes can create cues that are used in social interactions and are linked to particular personality traits or behaviours (2).

The complex interplay between the gut and brain has been speculated about for a while. Some early reports associate gastrointestinal functioning with mental health and go back all the way to the late 18th or early 19th century. But over the past few years, there has been a resurgence in research about the link between the gut and brain, thanks to recent technological advances in sequencing microorganisms. The authors of the UC San Diego study that examined loneliness and the gut wanted to examine how ‘even seemingly “fuzzy” concepts, like loneliness and wisdom, can be related to and perhaps even influenced by “hard” biological entities’ (2).

Loneliness has become a serious public health problem linked with increased morbidity and mortality. The gut microbiome may play an important role in this correlation. Over the years, the capacity of gut microbes to communicate with the brain and modulate behavior has emerged as a novel concept in health and disease. The ‘microbiota-gut-brain-axis’ involves two-way signalling between the gastrointestinal and central nervous systems, and it is regulated at the neural, hormonal and immunological levels (3). In previous studies, gut microbial diversity has been shown to be associated with greater emotional well-being as well as larger social networks (1).

In the UC San Diego study, 184 people between the ages of 21 and 97 were asked questions in order to assess their feelings of wisdom, compassion, loneliness, social support and social engagement. Using their responses in conjunction with a study of their gut microbes (through fecal samples), the study analysed the microbiome of these participants and sequenced it to look for alpha and beta diversity in the microbiome (1). Alpha diversity is the ecological diversity (i.e. the richness and compositional complexity) of a single sample, while beta diversity measures the similarity or difference of microbial community composition between different samples.

As the researchers hypothesized, increased loneliness and decreased compassion, social support, wisdom, social engagement and social support were found to be associated with decreased diversity of the gut microbiome and vice versa. After adjusting for multiple comparisons and other factors, compassion and wisdom remained significant predictors of the diversity of the gut microbiome. A diverse microbiome is a healthy one. The effects were also studied to ensure that there was no interaction with age or gender for these results. (1, 3).

What the findings mean

The way by which compassion, wisdom and loneliness may be tied to gut microbial diversity is unknown. It is believed, based on previous studies, that reduced alpha-diversity (diversity in the gut microbiome) may reflect poor mental and physical health. Low microbial diversity also translates into diseases like inflammatory bowel disease, major depressive disorder and obesity.

The results of the UC San Diego study demonstrated that the gut microbiome is agreeably influenced by subjective loneliness or perceived social support and isolation, beyond objective social network size. It also indicates that a pro-social attitude, signified by social engagement compassion may positively impact gut microbiome diversity and vice versa.

This question, however, requires further examination. Simply put, does a less diverse gut microbiome lead to behaviours that can increase loneliness? Or does loneliness and lesser social interaction lead to a less diverse gut microbiome? Further research following this study can help provide more actionable interventions. Increased levels of compassion, social support, engagement and wisdom were associated with more diverse gut microbiomes. Meanwhile, loneliness was associated with dampened microbial diversity, especially amongst the older adult population. (6)

Research also discovered that not only do married couples have more similar gut microbiota but they also harbour microbial communities of greater diversity and richness in comparison to those living alone (3).

These findings have potential clinical implications for developing interventions to reduce loneliness and its results. Working on increasing perceived social support and participation in social activities may serve as an antidote to loneliness.

Prior research has also shown that behavioural and psychosocial interventions can reduce the pro-inflammatory gene expressions associated with loneliness (5). Thus, it can be concluded that loneliness may result in decreased stability of the gut microbiome and reduced resistance to stress-inducing events, leading to adverse physiological outcomes like inflammation. Bacterial communities with low alpha-diversity may not result in disease, but they may not be conducive for preventing disease.


Gut health refers to the balance of microorganisms that inhabit the gastrointestinal tract. A healthy gut is a diverse gut. Research suggests that gut health has a profound effect on both physical and mental health. A new study suggests that the diversity of the gut microbiome could both mould or be moulded by loneliness. So which one comes first? “We cannot know for sure at this point, but my guess is that it is likely a bit of both,” says Nguyen the head researcher of the study.

The study suggests that lonely people ‘may be more susceptible to developing different diseases while having a supportive social circle as well as a deeper sense of wisdom and compassion may protect against the instability of the gut microbiome, particularly at an older age.

Disclaimer: The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns and before undertaking a new healthcare regimen including making any dietary or lifestyle changes.



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