For example, in the case of ultra-processed foods (UPF) which are factory-made ‘products’ high in fat, salt and sugar (HFSS) rather than kitchen-made wholesome meals, there are three key linkages.
First, the ‘low fibre’ connection. These foods lack a ‘real food’ matrix, they are pre-digested and lack fibre content on which beneficial gut bacteria thrive. Starved of fibre, the good bacteria may die off or even begin to consume the gut’s protective mucus lining, leading to dysbiosis and reduced production of short-chain fatty acids (SCFA) that are anti-inflammatory, help in maintaining intestinal wall lining thereby preventing leaky gut. They also help in preventing cancer of the colon.
Second is the ‘high chemical’ connection. Chemicals in these ‘junk foods’ act as hidden disruptors. For instance, emulsifiers through their detergent effect can wash off the gut lining; artificial sweeteners can trick bacteria and promote glucose intolerance. Preservatives meant to prevent microbial growth in packages can even kill beneficial microbes, and food colours can trigger immune system and allergic responses.
Third and most concerning is the ‘high sugar’ connection. Sugar acts as a readily available ‘fast fuel’ for opportunistic pathogens like E coli and Candida sp, which can outgrow beneficial Bifidobacteria sp, Lactobacilli sp, leading to non-alcoholic fatty liver disease, through dysbiosis, leaky gut, drop in SCFA levels, rise in ethanol and acetaldehyde levels. Studies also point to the ability of opportunistic bacteria to biologically ‘hack’ the brain to crave for more sugar, making UPFs addictive, which explains the aggressive marketing and misleading labelling of these bad foods.
The intensive rearing of animals for food involves antibiotic use which is a big concern. Indiscriminate antibiotic use in poultry, dairy, and aquaculture can lead to residues of antibiotics in fish, meat, milk, and eggs. This chronic, low-level exposure on one hand kills beneficial gut bacteria (yielding into dysbiosis, reduced bacteria diversity), and on the other, allows for selection pressure to dominate making bacteria resistant — contributing to the ‘no-longer silent pandemic’ of antimicrobial resistance (AMR).
In the case of agriculture, pesticide residues on crops are known to be linked to gut imbalances and endocrine disruption. Certain pesticides are known to interfere with the estrobolome, the specific collection of gut bacteria that regulates estrogen metabolism, leading to hormonal imbalances.
There are also reports of increased cortisol, decreased thyroid (T3), insulin resistance through pathways of low-grade inflammation. Combination of food and water with pathogens (such as Salmonella sp, Campylobacter sp) can significantly disturb the gut microbiome leading to dysbiosis.
Fixing food systems
Health of the gut microbiome is known to be directly linked with the health of the people. Fixing the food systems to make them more sustainable will go a long-way in not just providing food with less chemicals but more diversity and nutrition.
Diversity in food becomes important, because only then different bacteria within our gut microbiome, that perform different and important functions for the body, will be able to feed on different food sources and thrive. It is therefore often said that we must eat to feed the gut, and not ourselves.
Making our food systems sustainable will also help with co-benefits like improving livelihoods, improving soil health, and preventing damage to environment and climate.
This needs rethinking and transition as sustainability in food systems is linked to who grows our food. Is it made in factories, comes to us from far-off distances or is grown locally. It is about how we grow our food such as in a chemical-intensive way characterised by monocropping, excessive water uses and soil degradation.
It is also about what we grow — rich in diversity or otherwise — and, most importantly, what we eat — ultra-processed and packaged or fresh and colorful plate filled with nutrition. Such a transition needs a reform and systems-based long-term approach.