News and Opinions  –  2017

Food, microbes and health

Glossary

Microbiome: the ecosystem of bacteria hosted by humans in the gut, skin, mouth nose etc. The collection of different species living in the microbiome is referred to as microbiota.

Symbiotics: two organisms living in close proximity where both benefit from the association.

Commensals: two organisms living in close proximity where one benefits from the association without affecting the other.

Probiotics: Bacteria that promote health; generally refers to lactobacilli.

Prebiotics: Substances that favour growth of symbiotic or commensal bacteria, often sugars that are not taken up by the (human) host.

Synbiotics: Preparations (tablets, capsules or mixtures) that contain both probiotics and prebiotics.

2017-08-31

Infectious diseases and antibiotic resistance are related with nutrition through intricate connections, which are poorly understood. Several hypotheses have been proposed suggesting that our gut microbiome is instrumental for our health in many ways.

It is beyond doubt clear that our diet affects us in many ways. A varied diet with sufficient nutrients, prebiotics and probiotics are key to maintaining good health and reducing infections. By improving access to safe and nutritious food, antibiotic use could be decreased, thus reducing selection for antibiotic resistance.

There is probiotics in yoghurt.

Infectious diseases and antibiotic resistance are related with nutrition through intricate connections, which are poorly understood. It has long been known that access to sufficient and varied nutrients is essential for proper function of cells and tissues, including our immune system. As examples, deficiency of vitamin C causes scurvy, deficiency of vitamin A can cause blindness and iron deficiency causes fatigue.

More recently, it has become apparent that our own non-pathogenic microbes also affect our health, and that the foods we eat affect our microbial community.  Several hypotheses have been proposed suggesting that our gut microbiome is instrumental for our health in many ways. The advent of high throughput and whole genome sequencing have made it possible to understand the composition of this microbiome much better than older methods were ever capable of, sparking interest in the health effects of the microbiome. Other important aspects are that antibiotics can severely disrupt the microbiome and that antibiotics are often used in the treatment of severe malnutrition. Read more about these interlinkages in our factsheet on ABR and nutrition. [Link to Nutrition and ABR fact sheet]

Synbiotics preventing serious infections

A study performed in India studied the effect of a synbiotic preparation consisting of the probiotic Lactobacillus plantarum and prebiotic fructooligosaccharide in infants. Previous smaller studies with probiotics and synbiotics have provided some support for the hypothesis that probiotic bacteria may reduce sepsis in infants prior to maturation of the gut microbiome. Almost 2300 healthy infants received the synbiotic and a similar group served as a control. The children were followed for two months, looking for bloodstream infections, a common cause of death among infants. The study reports differences between the groups for several outcome markers: death and sepsis (5.5% vs 9.0%, primary outcome), sepsis (5.1% vs 8.9%), diarrhoea (0.5% vs 2.6%), local infections (0.7% vs 1.5%) and omphalitis (infection of the umbilical cord, 0.1% vs 0.6%). There was no significant difference in otitis and abscesses.

Probiotics, diet and microbiome

The exact pathways by which nutrition, symbiotic or commensal bacteria and antibiotic resistance are connected are still very much undefined. However, research data suggesting strong interdependencies, just like in all ecosystems, is accumulating. Among probiotic bacteria, the most studied species are probably lactobacilli such as L. plantarum used in the above study. Lactobacilli are found in many traditional fermented foods – yoghurt, kimchi, sauerkraut and sourdough bread to mention a few. The modern food industry has also created foods supplemented with some of these bacteria, and they are often vigorously marketed with strong claims of positive health effects, many of which still remain to be validated by research.

There are two important aspects of dietary supplements with bacteria. One is that the mature gut microbiome is relatively resilient to change. This means that while it is possible to modify the composition and balance of the microbiota, large and sustained changes are difficult to achieve. Such changes are perhaps not possible to achieve without making major changes in the diet to foods that promote a diverse microbiome. The second is that for any ecosystem, including our microbiome, diversity is key. However, studying the effects of diet on health and microbiome are by necessity limited to studying one or two factors or bacterial species at a time to limit confounding factors. This makes it difficult to draw conclusions from the interventions in the studies. At the same time, oversimplified research data may easily lead to misconceptions of the topic.

Food as medicine?

It is beyond doubt clear that our diet affects us in many ways. A varied diet with sufficient nutrients, prebiotics and probiotics are key to maintaining good health and reducing infections. By improving access to safe and nutritious food, antibiotic use could be significantly decreased and thus we are able to reduce the forces that select for antibiotic resistance. The role of probiotic and synbiotic preparations in health care is still to be determined. Some examples suggest a role in treating disease, and others, such as the study referenced above, provide evidence for the role of bacteria in preventing bacterial infections.

Glossary

Microbiome: the ecosystem of bacteria hosted by humans in the gut, skin, mouth nose etc. The collection of different species living in the microbiome is referred to as microbiota.

Symbiotics: two organisms living in close proximity where both benefit from the association.

Commensals: two organisms living in close proximity where one benefits from the association without affecting the other.

Probiotics: Bacteria that promote health; generally refers to lactobacilli.

Prebiotics: Substances that favour growth of symbiotic or commensal bacteria, often sugars that are not taken up by the (human) host.

Synbiotics: Preparations (tablets, capsules or mixtures) that contain both probiotics and prebiotics.

Links and further reading

Download ReAct’s factsheet on Antibiotic use, resistance and the link to nutrition.

Download ReAct’s factsheet on The human microbiome.

Article in Nature: A randomized synbiotic trial to prevent sepsis among infants in rural India.

ReAct educational material

Reimagining Resistance

ReAct Toolbox

Spread of resistant bacteria

What can I do as an individual to help limit antibiotic resistance development and spread of antibiotic resistant bacteria?