Reduced microbiotic richness in the human gut due to decreased dietary diversity is associated with common diseases, including Type-2 diabetes, obesity and inflammatory bowel disease, scientists say.

Changes in farming practices over the last 50 years have resulted in decreased agro-diversity which, in turn, has resulted in decreased dietary diversity, researchers said.

Mark Heiman from biotechnology company MicroBiome Therapeutics and Frank Greenway of the Pennington Biomedical Research Centre in US evaluated the significant impact of this change in dietary richness on human health. They described how the reduction in dietary diversity has changed the richness of human gut microbiota, the community of microorganisms living in the gut.

The researchers point out that healthy individuals have diverse gut microbiota and many of the common pathologies of the 21st century, including Type-2 diabetes, obesity and inflammatory bowel disease, are associated with reduced microbiotic richness.

Gut microbiota function as an endocrine organ, metabolising specific nutrients from the diet and producing specific substances that act as metabolic signals in the host.

It follows then that highly specialised diets will change the landscape of the gut microbiome over time. In fact, it takes only a few days of changing diet to alter the micro biotic makeup of the human gut. If the dietary change involves elimination of one or more macronutrients, humans are essentially selecting for some micro biotic species over others, researchers said. The importance of microbiota diversity cannot be overstated. They produce an abundance of important molecules for the host and with increased variation comes increased adaptability and an increased range of physiological responses. “The greater the repertoire of signals, the more likely is the ability to maintain homeostasis when dietary intake is perturbed,” researchers said.