When we speak about the relationship between food and health, we tend to think about what are the most suitable diet, the most wholesome ingredients, the recipes that are not too stodgy due to their high fat and sugar content, and the right balance of proteins, carbohydrates and other nutrients. The huge number of microscopic bacteria that populate our intestine is not exactly the first thing that comes to mind. Yet so-called gut microbiota are the litmus test of our health.
To explore the connection between food and health as thoroughly as possible, Slow Food has published a position paper entitled Our Food, Our Health: Nourishing biodiversity to heal ourselves and the planet, much of which is devoted to the thousand billion and more bacteria, viruses, fungi and protozoa–weighing a total of about one and a half kilos–which by communicating with each other act as if they are a single organism. Given its complexity and importance in its interaction with the rest of our organism, scientists regard the latter almost as a second brain.
Why and how is microbiota important?
Gut microbiota constitute an ecosystem and contain a number of genes at least a hundredfold that of the human genome. Any alterations to its balance may give rise to a variety of gastrointestinal complaints but also to pathologies such as obesity, metabolic syndrome, arteriosclerosis and other cardiovascular, neurological and psychiatric diseases.
In February 2018, Eran Segal, a researcher at the Weizmann Institute of Science in Israel, and a team of colleagues published an article entitled Environment dominates over host genetics in shaping human gut microbiota in the scientific journal Nature. Their study highlights the way in which the factors that determine gut microbiota are not only genetic but also non-genetic, and are associated, for example, with diet and lifestyle.
The gut microbiota community is, in fact, exceptionally dynamic and microorganisms may be absorbed by food, water and the surrounding environment.
If the health of microbiota and human health are connected, then it is important to understand how to maintain that of the microbiota themselves.
A fundamental factor to bear in mind is the soil.
Everything that constitutes food comes, directly and indirectly, from the soil. In 2019, Blum, Zechmeister-Boltenstern and Keiblinger of the Institute of Soil Research of the University of Natural Resources and Life Sciences in Vienna published a study on the relationship, writing that, “The increasing use of agrochemicals, low plant biodiversity and rigorous soil management practices have a negative effect on the biodiversity of crop epiphytes and endophytes [that is, of microorganisms, editor’s note]. They go on to explain that “These developments concur with an increase in lifestyle diseases related to the human intestinal microbiome”.*
*Microbiota and microbiome are not synonyms: the microbiome is the genetic material of microbiota, namely the genes that microbiota are capable of expressing. The meanings of the two concepts are in certain respects similar but not perfectly identical.
This is why the connection between microbiota and agriculture is important: the soil is not only where edible crops grow: it is also home to billions of insects, fungi, bacteria, yeasts and other useful microorganisms, indispensable for making it fertile and productive and–as we have seen–capable of having positive effects on microbiota. It contains an invisible biodiversity that is destroyed and cancelled by the use of pesticides and herbicides such as glyphosate.
Livestock farming works the same way. Animals at pasture can feed on grass and vegetation that grows spontaneously and is rich in biodiversity. Hence a diet beneficial not only for the animals but also, consequently, for anyone who drinks their milk and eats their meat. None of this occurs with animals kept in barns, as is the case on factory farms, which means bidding farewell to the benefits of contact with the land.
Soil and microbiota are not only connected by the food that originates from the substratum itself. Contact alone is enough to favour exposure to beneficial gut microorganisms. In the course of the last century, the dramatic growth in urbanisation induced a significant decrease in the natural biodiversity of the environment in towns and cities, thus reducing exposure to environmental microbes too. According to a group of Finnish researchers, “reduced contact of people with natural environmental features and biodiversity may adversely affect the human commensal microbiota and its immunomodulatory capacity”. The consequences? Not only allergies, say, but also a variety of gastrointestinal complaints, pathologies such as obesity, metabolic syndrome, arteriosclerosis and other non-communicable diseases, as pointed out in another study by researchers at the University of Fribourg.
The way in which foodstuffs are processed may influence the health of microbiota: the effect of high-calorie packaged industrial foods, rich in sugar, fat and salt–increasingly common in the diets of western countries–is to alter intestinal microbiota as a result of the treatments ingredients undergo before and after being gathered, as shown in the study entitled Influence of diet on the gut microbiome and implications for human health published in the April 2017 issue of the Journal of Translational Medicine.
The importance of adopting a “One Health” approach
Let us return for a moment to Blum, Zechmeister-Boltenstern and Keiblinger’s study: the authors write that, “it may be useful to adopt a different perspective and to consider the human intestinal microbiome as well as the soil/root microbiome as ‘superorganisms’ which, by close contact, replenish each other with inoculants, genes and growth-sustaining molecules”. Soil, animals and microbiota, planet, natural environment and humans–it is wrong (and unadvisable) to think in straight lines. The so-called “One Health” approach, whereby health is connected with everything and for all, recognises the existence of an indissoluble link between the health of human beings and that of animals, forms of plant life and the environment: the problems that afflict each of the categories of the living have to be addressed within the framework of an integrated approach.
Defending food biodiversity means fighting the excessive power of the chemical industry, intensive agriculture, industrial livestock farming and indiscriminate fishing. But promoting the production of good, clean and fair food has effects in other ambits too: on the health of the environment, on the safety of ecosystems, the economic survival of small-scale producers, the conservation of local traditions and cultures, and, of course and above all, on human health.
Blum WEH, Zechmeister-Boltenstern S, Keiblinger KM, Does Soil Contribute to the Human Gut Microbiome? Microorganisms 2019
149 Wikoff WR, Anfora AT, Liu J, et al., Metabolomics analysis reveals large effects of gut microflora on mammalian blood metabolites. Proceedings of the National Academy of Sciences. 2009
150 Microbiome, in ‘Nature News’, February 15 2022
151 Blum HE. The microbiome: A key player in human health and disease. Journal of Healthcare Communications, 2017
152 Rothschild D, Weissbrod O, Barkan E, et al,. Environment dominates over host genetics in shaping human gut microbiota, in ‘Nature’, 2018