We all know that eating vegetables and fruits are good for
us. Then we learned that the “goodness”
comes from the dietary fibers in these foods.
According to the American Association of
Cereal Chemists, dietary fiber is the edible parts of plants or analogous
carbohydrates that are resistant to digestion and absorption in the human small
intestine with complete or partial fermentation in the large intestine. Dietary fiber incudes polysaccharides, oligosaccharides,
lignin and associated plant substances. Dietary fibers promote beneficial
physiological effects including laxation, and/or blood cholesterol attenuation,
and/or blood glucose attenuation. According
to this definition, dietary fibers are resistant to digestion—so how does it
benefit us? It turns out that dietary
fibers are good for us by feeding good microbes in our gut.
Trillions of bacteria live in our gut -- there are about ten
times more bacterial cells in the average person's body than human ones. Past researches have shown that these
bacteria are central to human metabolism and general well-being.
In a recent issue of Nature, a group of researchers reported that a particular gene
sequence in one group of gut bacteria, Bacteroidetes, allows these microbes to digest
complex sugars known as xyloglucans, which make up to 25 per cent of the dry
weight of dietary fruit and vegetables including lettuce, onion, eggplant and
tomatoes. The study further shows that
about 92 per cent of the population harbors bacteria with a variant of the gene
sequence, according to a survey of public genome data from 250 adult
humans.
Because Bacteroidetes are families of the "good
bacteria" we want to cultivate in our guts, having enough “dietary fibers”
to feed them is essential to maintain a healthy and balanced gut microbiota
population, which researches have shown to have implications in metabolic syndromes
such as obesity, diabetes, and cardiovascular conditions.
Journal
Reference: Johan Larsbrink, Theresa E. Rogers, Glyn R. Hemsworth, Lauren S.
McKee, Alexandra S. Tauzin, Oliver Spadiut, Stefan Klinter, Nicholas A. Pudlo,
Karthik Urs, Nicole M. Koropatkin, A. Louise Creagh, Charles A. Haynes, Amelia
G. Kelly, Stefan Nilsson Cederholm, Gideon J. Davies, Eric C. Martens, Harry
Brumer. A discrete genetic locus confers xyloglucan metabolism in select human
gut Bacteroidetes. Nature, 2014; DOI: 10.1038/nature12907
Thanks for reading.
Connie
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