The link between gut bacteria, asthma and anorexia

Healthy gut flora - iStock
Healthy gut flora - iStock

What on earth do asthma and anorexia nervosa have in common?

The unifying factor is healthy gut bacteria or healthy microorganisms (also called “flora” or “microbiota”) that live in the colon.

Two recent articles in MedicalBrief highlighted the importance of healthy colonic flora.

Anorexia nervosa

The article Gut microbiota difference in anorexia nervosa reports that researchers at the University of North Carolina School of Medicine found that the microbial communities in people suffering from anorexia nervosa differed a great deal from those found in individuals without this eating disorder. In addition, there was a link between the bacterial imbalance and some of the psychological symptoms of anorexia nervosa.

The results of this study indicate that the millions and trillions of microorganisms that live in the human gut possibly influence what is known as the “gut-brain axis”.

The idea that there is a link between gut microbiota and depression is also being investigated. Dinan & Cryan suggested that there is a need to study the association between our gut flora and mood and to consider therapeutic strategies to develop psychobiotic-based therapies.

Read: Probiotics and antibiotics

Considering that up to 3 million people suffer from anorexia nervosa in the USA and that this eating disorder is increasing in most western countries, including South Africa, this new link may not only explain some of the symptoms but also provide a treatment option to alleviate the anxiety and depression associated with anorexia.

In the current American study, the researchers found that 16 female anorexia patients had a much smaller diversity of beneficial microbiological species in the gut when they were admitted to the UNC Centre of Excellence for Eating Disorders, than when they were discharged and their weight had stabilised.

The results of this study suggest that the use of beneficial microorganisms could be a treatment option to prevent anorexia nervosa or to alleviate some of the negative symptoms of patients when they have an eating disorder.

Childhood asthma

The second article Gut bacteria protect kids against asthma, deals with research conducted at the University of British Columbia (BC) and the BC Children’s Hospital with 319 children. The investigators found that children can be protected against developing asthma if they acquire 4 types of gut microorganisms by the time they reach the age of 3 months. 

Childhood asthma affects up to 20% of children in western countries and is also on the rise in South Africa as our rural population becomes increasingly westernised and urbanised. The “hygiene hypothesis”, was suggested in 1989 by David Strachan.

The hygiene hypothesis states that we are too clean and protect our children so efficiently against normal exposure to microorganisms and other agents (both beneficial and pathogenic) that the children do not develop natural immunity and succumb to diseases such as asthma at an alarming rate.

In 2014, West pointed out that early environmental conditions, such as a Caesarean delivery, can disturb colonisation of the gut with the microorganisms required for a healthy flora and lead to a rise in allergic conditions.

Read: Good hygiene bad for bowels?

The Canadian study found that there is a ‘critical window’ early in life where a disturbance of the gut microbiota influences the development of future asthma. Four types of bacteria, namely Faecalibacterium, Lachnospira, Veillonella and Rothia, were significantly decreased in the children who were at risk of asthma at the age of 3 months.

These bacteria have been nicknamed FLVR and they appear to be critical for reducing a child’s chances of developing asthma, a disease that can be fatal in young children.

The next step will be to determine how to ensure that infants do acquire FLVR and develop a healthy gut microbiota to protect them against childhood asthma.

An experiment where pregnant women used probiotics (“beneficial microorganisms”) during pregnancy in a large population-based, cohort study, showed a decrease in the risk of eczema and nasal congestion, sneezing, cough, and inflamed eyes (rhinoconjunctivitis), but not in asthma. Despite the conclusion reached in 2014 by West that the use of probiotics did not influence childhood asthma, the latest study indicates that exposure to the right kind of microorganisms during the critical window of opportunity very early in a child’s life may well protect the child against asthma.

The future

Further research is obviously required in both the fields of anorexia nervosa and childhood asthma to determine how an ideal gut flora can be created and maintained to prevent or perhaps even to alleviate these conditions.

In the meanwhile it is a good idea to take probiotics after a course of antibiotics, and to ensure that infants do receive a probiotic, particularly if they have been born by Caesarean section or if they are not breastfed.

And keep in mind that exposure to the normal atmosphere and the environment during infancy and childhood is also important. The more we disinfect our environment the more sensitive we will become.

Read more:

Food allergy-preventing gut bacteria discovered

Diet shifts change gut bacteria

Gut bacteria may protect against obesity


- Arrieta MC et al (2015). Early infancy microbial and metabolic alterations affect the risk of childhood asthma. Sci Transl Med, 7(307):307ra152.

- Dinan TG, Cryan JF (2013). Melancholic microbes: a link between gut microbiota and depression? Neurogastroenterol Motil, 25(9):713-9. 

- Kleiman SC et al (2015). The intestinal microbiota in acute anorexia nervosa and during renourishment: relationship to depression, anxiety and eating disorder psychopathology. Psychosom Med, 2015 Oct 1.

- MedicalBrief (2015A). Gut microbiota difference in anorexia nervosa. Published 7 Oct 2015.

- MedicalBrief (2015B). Gut bacteria protect kids against asthma. Published 6 Oct 2015.

- Strachan DP (2000). Family size, infection and atopy: the first decade of the “hygiene hypothesis”/ Thorax, 55, Suppl 1: S2-10; West CE (2014). Gut microbiota and allergic disease: new findings. Curr Opin Clin Nutr Metab Care, 17(3):261-6.

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