LOOK CLOSER AT YOUR MICROBES: We Are Part of a Single, Yet Damaged «Superorganism»
Photo by Free Nomad on Unsplash
You are what you eat. At least when it comes to the microbiome. Recent studies have shown that your body contains the same bacteria and fungi found in fermented foods. However, the state of your microbiome depends not only on your diet, but also on the people you interact with and the environment you live in. It can either improve or deteriorate, significantly impacting your health.
CIVILIZATION KILLS MICROBES
H
umans and microbes have lived in symbiosis for millions of years. It’s not surprising — nearly all living organisms on our planet are designed this way. Survival is easier together. So, humans and microbes didn’t reinvent the wheel and also joined forces for a common interest: food. Some organisms excel at obtaining it, while others excel at processing it. Everything was going well until humans decided to improve what nature had already perfected radically. Problems began with the Neolithic Revolution. The transition from hunter-gatherers to urban civilization negatively affected the bacterial environment in human guts.
Stanford University researchers compared the microbiomes of indigenous people in Tanzania, California, and Nepal. They found that industrialization and urbanization have altered human lifestyles, reducing bacterial diversity. Today’s microbiome is significantly different from that of our ancestors — many bacteria have simply vanished.
While the average member of the Hadza tribe in Africa hosts 730 microbes, a Californian has only 277, and a Nepali, depending on their occupation, has between 317 and 416. «Civilized» people not only have fewer bacteria, but these microbes are also much more damaged by oxidative processes linked to chronic gut inflammation.
DAMAGED «SUPERORGANISM»
Changes in the microbiome are closely linked to lifestyle and diet and disease incidence and patterns. Cancer treatment, for instance, considers this. Scientists have observed that gut bacteria influence the effectiveness of anti-cancer drugs.
Therefore, studying the balance of microbial communities in the gut could aid in developing next-generation drugs. However, current probiotics and other supplements aimed at improving the microbiota have not yet proven effective in preventing obesity or cancer.
The composition of the microbiota is influenced by everything: climate, diet, and lifestyle. Much depends on the region where a person resides. The soil and our gut contain roughly the same number of active microorganisms. However, the current diversity in our bodies is only 10% of the soil’s biodiversity. It is likely that an evolutionary link formed between soil and human microbiomes, which was later disrupted.
Today, the diversity of microorganisms within human communities is much lower than between different communities — urban areas have the most differentiated individual microbiomes. Compared to the pre-industrial era, the microbial cycle in urban environments is clearly disrupted.
Urban dwellers rarely come into contact with soil and use antibiotics, hygiene products, and processed foods. On the other hand, agricultural practices contribute to soil degradation and reduced crop biodiversity. It appears that civilization has damaged the unified microbiome of the symbiotic «superorganism».
LOOK CLOSER AT YOUR NEIGHBOR’S MICROBIOME!
The human microbiome begins to form even before birth and continues to develop between 3 and 46 months of age, influenced by a range of factors — many of which are entirely unexpected. The ratio of bacteria in your body is also affected by the social contacts you maintain throughout your life.
A team led by Professor Nicola Segata from the University of Trento in Italy collected nearly 10,000 samples from residents of 20 countries across five continents. Among their findings were the following:
34% of gut bacteria strains are shared between mothers and their children up to 3 years old, dropping to 19% by 18 years old and just 15% by 30. The microbial set of neighboring villages always differs, with more distance leading to more differences. Even twins living apart have vastly different microbiomes. Interestingly, spouses’ microbiomes become «one flesh», almost in the biblical sense. After divorce, their microbiomes diverge as well. Typically, family members, friends, and colleagues share similar microbes.
Researchers suspect that some non-infectious diseases could spread through «malfunctions» in microbiomes, potentially linked to obesity, diabetes, and even cancer. However, the impact of this exchange can also be positive.
Strangely, scientists still don’t fully understand how microbiota exchange occurs. Kissing, breathing, touching, and sharing food and household items are the most common theories. However, these don’t clarify how long contact must last for sufficient microbiota transfer and colonization in another body.
There is another hypothesis: the similarity in the microbiomes of people living together may be more about shared diets than bacteria exchange.
YOU ARE WHAT YOU EAT?
Under Nicola Segata’s guidance, researchers compiled a catalog of microbes from over 2,500 cheeses, meats, and other food products, comparing them with 600 known food microbiomes. Fermented foods were primarily considered — from salami to sauerkraut, kimchi to kefir — as well as fresh meat, fish, fruits, and vegetables.
The study brought unexpected results. Seemingly similar foods contained different microbes. For instance, the composition of lactic acid bacteria varied across dairy products. Dutch blue cheese contained Lactobacillus species different from Italian fontina and mozzarella.
Meanwhile, microbes from coffee, kombucha, and Chinese pu-erh tea were similar to those found in alcoholic beverages. Pulque — a sour Mexican agave wine — African palm wine and cheese brine revealed up to 50% previously unknown microorganisms.
Biologists found a certain degree of overlap between the types of microorganisms in food and the human body. In adults’ guts, the overlap was 3%, in children 8%, and more than 50% in newborns, who acquire them from breast milk. According to Segata, it’s not necessarily true that all these microbes came from food.
They might have settled in human guts and begun circulating among people much earlier. However, scientists hope that further research will shed light on this question as well.
Original research:
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