Although we have been taught in schools that our stomachs have certain acids to help us digest our food, evolutionary link between diet and stomach acidity was not completely clear. In fact, now team of scientists from the North Carolina State University, Washington University and the University of Colorado, Boulder have conducted a study, which shows that high levels of stomach acidity developed not to help animals break down food, but to defend animals against food poisoning.
This research raises questions about human digestive system as well and will seek to answer how modern lifestyle may affect our stomach acidity and the microbial communities that live in human guts.
This research was started because scientists wanted to better the understanding of the relationship between stomach acidity, diet and the microbes that live in the guts of birds and mammals. The ultimate goal of the research is to shed some new light on the role of the human stomach acidity in influencing gut microbes and how important are they for human health.
Scientists researched data on stomach acidity and diet in birds and mammals. They examined all of the existing literature on this topic and found data on 68 species. Then they collected data on the natural feeding habits of each species. Finally researchers ran an analysis to see how feeding behaviour was related to stomach acidity.
Analysis showed that scavengers (species that eat food with high risk of microbial contamination) have more acids in their stomachs. This allowed scientists to think that acidity in stomach is not so much to break down food, but to prevent food poisoning and control bacteria traveling through to the gut.
DeAnna Beasley, one of the authors of the study, said that such findings do confirm their hypothesis, which was needed in order to move on with this research. She explained that “the next step will be for scientists to examine the microbial ecosystems in the guts of these animals to see how these ecosystems have evolved. Do animals with high stomach acidity have smaller or less diverse populations of gut microbes? Or do they simply host microbes that can survive in acidic environments?”
However, research already provided surprises. The researchers classified humans as omnivores, but human stomachs have the high acidity levels normally associated with scavengers. Also, literature shows that acidity in human stomach can be altered significantly by medical treatments – from surgery to antacids. This raises questions about human evolution and possible changes in our digestive systems related to contemporary life style and diet.
Scientists are already addressing these questions, researching possible changes in our stomachs, our gut microbes and – ultimately – our health. We know that our modern lives are not entirely suitable to our biological systems. However, researches like this can help us understand better how our diet can influence evolutionary changes in our digestive systems and why our acidity levels are like ones of those species that eat rotting meat and pretty much everything.