It’s common knowledge today that fiber, which comes from vegetables or whole-grain products, is a healthful and important part of our daily meals. But what is fiber, and why is it good for you?
Fiber—cellulose, the stringy stuff that leaves, stems, roots, stalks, and tree trunks are made of—helps keep our intestinal flora (bacteria known to scientists as the gut microbiome) happy and balanced.
Fiber is the starting point of a natural food chain, beginning with bacteria that can digest cellulose, thus providing the rest of our microbiome with a balanced diet. However, the eating habits in industrialized societies are far removed from those of ancient humans and impact our intestinal flora; newly discovered cellulose-degrading bacteria are being lost from the human gut microbiome, especially in developed countries.
Mammals, including humans, rely on their gut’s microbial community to break down plant cell wall components, notably cellulose and associated polysaccharides. But there is limited evidence for cellulose fermentation in the human gut, despite the benefits of cellulose-containing dietary fiber for gut-microbiome health and overall human wellbeing.
Urban societies are losing healthful gut microbes
According to a study just published in the prestigious journal Science entitled, “Cryptic diversity of cellulose-degrading gut bacteria in industrialized humans,” people living in urban societies are losing healthful gut microbes that turn fiber into food for a healthy digestive tract.
Prof. Itzhak Mizrahi at Ben-Gurion University (BGU) of the Negev in Beersheba, with support from the Weizmann Institute of Science in Rehovot and international collaborators in the US and Europe, conducted the research. “Throughout human evolution, fiber has always been a mainstay of the human diet,” explains lead investigator Sarah Moraïs from BGU. “It is also a main component in the diet of our primate ancestors. Fiber keeps our intestinal flora healthy.”
Moraïs and her colleagues identified important new members of the human gut microbiome – cellulose-degrading bacteria named Ruminococcus. These bacteria degrade cellulose by producing large, highly specialized extracellular protein complexes called cellulosomes.