When I was growing up my mother had a single cutting board that she used for vegetables, meat, and the occasional finger. Although her cooking skills were limited, they were also quite conventional and her multi-purpose cutting board raised no eyebrows. These days, along with raised eyebrows such a practice could infect families with pathogenic Salmonella and E. coli bacteria. Not so many years back, chicken was not routinely overrun with unpleasant bacteria. What changed?
First the good news. Somewhere along our evolutionary path our bodies accepted and incorporated a host of bacterial colleagues now called the microbiome. The venture worked. Your biome houses as many tiny immigrants, weighing en masse between three and five pounds, as your body does cells. Accompanied by fungi, viruses, and certain microorganisms, this bacterial host is not hitching rides; it gives as well as gets, and over our shared trail has come to be essential for matters as apparently unrelated as digestion, immunity, and mood.
Despite the great 'weight' of the inhabitants of our biome, they respond flexibly--happily or not--to what gains entry. If you eat at that new Thai restaurant, the biome reacts to the unfamiliar input. Generally these changes are subtle and quickly return to whichever 'normal' you've established, but not always, and reasons for that are not well understood. The biome, which has been called a 'second brain', has major effects on digestion, weight, immunity--even your frame of mind. The role this plays in our mental and physical health is hard to overstate.
Bacteria are not created equal. We contain a mixture of 'good' and 'bad' bacteria and substances affect them differently. Bacteria compete for front-row seats and sustenance along the colon. When food is nutritious and adequate and no thumbs weight the scale, beneficial bacteria outnumber outlaws and order is maintained.
The bad news is that, over the planet but particularly in the US, a new venture has begun. For the most part it flies under the radar, but make no mistake it's pervasive. Every creature that lives, along with every square inch of land, air, and water, now accommodates a new partner. Unlike the one between us and our biomes, this partnership is not to the benefit of both.
Plants share the planet with us and require some of the same things we do--food and water come to mind. In addition, plants require three amino acids. Enzymes along what is known as the shikimate pathway produce the amino acids tryptophan, tyrosine, and phenylalanine, which bolster chlorophyll in plants for photosynthesis, without which most won't live.
Glyphosate, the star ingredient among a set of trade-secret so-called inert ingredients inhabiting the herbicide Roundup, kills by disrupting an enzyme known as EPSPS synthase (5-enolpyruvylshikimate 3-phosphate) along the plant's shikimate pathway. Glyphosate depletes these essential amino acids from plants not engineered (or resistant) to a state of "Roundup readiness". The EPSPS enzyme targeted by glyphosate resides in plants, not animals. Therefore, we are told, glyphosate has no effect on anything that is not a plant.
But the shikimate pathway is not confined solely to plants. The pathway occurs also in bacteria and fungi, including those that inhabit birds, mammals, aquatic life, insects, even soil. Of course our gut bacteria contain the shikimate pathway.
When our gut bacteria are functioning they provide from the food they help digest certain amino acids that our bodies can't produce. Coincidentally enough, those three amino acids are tryptophan, tyrosine, and phenylalanine. Here's some of what they do for us:
Tryptophan is a precursor to serotonin. Although you may associate serotonin with the brain and its lack with depression, the majority of serotonin--90% of it--is made in the digestive tract. As a gut neurotransmitter, serotonin affects nerves that power smooth-muscle function and blood flow; it's also involved in bone modeling and metabolic balance. When the gut is inflamed, serotonin is involved in immunity and angiogenesis. Low serotonin is associated with such gut disorders as inflammatory-bowel and celiac disease.
Made from phenylalanine, tyrosine is more or less a breeder of neurotransmitters that communicate within us. In addition to alertness, learning, and memory, tyrosine is necessary for thyroid function. Many people with autoimmune diseases also have thyroid problems.
Phenylalanine is used to produce proteins and other molecules, some of which enable signaling in the body. It comes in two slightly different molecular forms, one of which is used in the making of substances such as aspartame. More bad press arises from the inability of those who lack a certain enzyme to metabolize dietary phenylalanine.
When gut bacteria are exposed to glyphosate, they are unable to produce those amino acids.
It's been argued by industry proponents that bacteria in our biome are awash in tryptophan, tyrosine, and phenylalanine, presumably from our digestion of plants containing those substances (unless, of course, those plants had been desiccated prior to harvest with Roundup, as is increasingly the case). In other words, we are told that easy availability of those amino acids from digestion make it moot that our microbiome can no longer produce them. If that is so, that we don't need our gut bacteria to produce these three essential amino acids, then why do we house those bacteria? We would be providing them tenancy and getting nothing in return. While that may be a lofty sentiment, biology doesn't often work that way.
For the sake of argument consider that if Roundup's only fault was to deny us three amino acids, we might find ways (involving supplements) to live with that.
But despite the difficulty of looking into this with independent research, there are definite indications that the herbicide's effects are not so limited.
In the US today, cattle are increasingly afflicted by the disease of botulism. Researchers found that glyphosate and Roundup are more destructive to certain gut bacteria that hamper growth of the bacterium Clostridium botulinum, which unsurprisingly fosters botulism. In chickens, pathogenic bacteria are highly resistant to Roundup--in effect they're Roundup Ready--while most beneficial gut bacteria range from somewhat to highly susceptible. Very low concentrations of Roundup kill or incapacitate good bacteria, which fuels overgrowth of bad bacteria. As everyone knows, when outlaws gain the upper hand there's trouble.