A person who eats the typical Western diet consumes half the fiber recommended in many dietary guidelines. A recent commentary piece by researchers from the University of Alberta suggests this fiber gap presents a major problem, as dietary fiber is the primary source of nutrition accessible to gut bacteria in humans. They believe that increasing dietary fiber intake may be the best way to replenish the microbial gut biodiversity that has been damaged by the western diet.
The researchers proposed that the western diet, which is low in many essential nutrients, including fiber, has resulted in a loss of species that rely on fiber as an energy source as well as a reduction of fermentation end-products that are essential for a range of physiological and immunological functions. In other words, the western diet does not provide enough nutrients for us to develop healthy gut microbiota.
They link the depletion of the human gut microbiome to an increase in non-communicable disease (NCDs) such as obesity, cardiovascular disease, colon cancer, allergies, other atopic diseases (including asthma), autism, and autoimmune diseases that has taken place in recent decades.
“The role of the gut microbiome in NCDs is difficult to test in humans, but disease risk is epidemiologically linked to practices that disrupt the establishment of the gut microbiota early in life (such as cesarean sections, antibiotics, formula feeding), and pathologies are often associated with an aberrant microbiome,” the researchers said. “ In fact, comparisons of the gut microbiota in unindustrialized rural human communities from South America, Africa, and Papua New Guinea (which generally have a low prevalence of NCDs) with that of communities in the USA and Europe provide compelling evidence for a substantial decline of gut microbiome diversity through industrialization.”
The researchers suggest that a high-fiber diet may start to reverse the negative effects of the current low-fiber western diet. However they also pointed out that the costs could be prohibitive, as low-fiber, processed foods tend to be cheaper than high-fiber foods. They recommend government subsidies of foods with “established health benefits” and point out that spending money on improved diet is actually cheaper than the healthcare costs of continuing to follow a poor diet, both for the individual and society.
The commentary was published online on April 11, 2016, in Trends in Endocrinology & Metabolism.
Previous studies have linked fiber consumption with lowering total and LDL cholesterol, and regulating blood sugar for people with diabetes.
There are two type of fiber: soluble and insoluble. Soluble fiber can be found naturally in oats, peas, beans, apples, citrus fruits, carrots, barley and psyllium. Insoluble fiber can be found in whole wheat and grains, brown rice, fruit, broccoli, cabbage and dark leafy vegetables.