EXPLORINg KNOWLEDgE
FOLLOW YOuR GuT
The battle of the bulge may be won and lost by the microbes in your digestive system .
BY HEATHER BuSCHMAN , PH . D . ’ 08
EVER nOTiCE HOW SOmE PEOPlE diet and exercise like crazy but can ’ t seem to slim down , yet your best friend eats whatever she wants without gaining a pound ? You may blame it on genetics , but you ’ d be only half right . Because the genes to blame may not be yours .
“ Some of the things you think are influenced by your own genes are actually controlled by microbial DNA ,” says Rob Knight , professor in the UC San Diego School of Medicine and Jacobs School of Engineering . Knight is an expert in the human microbiome — the genetic makeup of all the microbes that live in and on us . He and other researchers have discovered that microbes in our guts play a big part in our health , especially body weight .
In fact , Knight can tell if you are lean or obese with 90 percent accuracy just by looking at the microbe populations living in your intestines . A look at your genome could yield only 60 percent accuracy .
Surprising ? Consider this : our bodies contain about 300 times more microbial genes than human genes . And while 99.99 percent of those human genes are the same from person to person , our microbiomes are radically diverse — we share only 10 percent in common with each other .
Researchers have found that an organism ’ s weight can be altered by differing gut microbes . Mice that received a microbial transplant from an obese person gained weight , while mice receiving transplants from lean people did not . Turns out those “ lean ” microbes help the mice digest food more efficiently , while the “ obese ” microbes appeared to influence behavior — the mice that received them ate more .
What ’ s next ? Knight and colleagues are creating a special facility at UC San Diego to design microbial communities that prevent or reverse weight gain . Knight also dreams of a day when — wait for it — a “ smart toilet ” sends a microbiome readout to your phone and your electronic medical record every time you flush . Such information could determine if you ’ re getting healthier or unhealthier , and also come with advice on how to stay in good shape .
KEEP yOuR guT HAPPy Rob Knight ’ s tips for a mighty microbiome .
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Avoid taking unnecessary antibiotics .
Eat lots of leafy green and brightly colored vegetables , fermented foods and fiber . Intestinal bacteria turn fiber into butyrate , a metabolite that reduces inflammation and feeds the cells that line the gut .
Limit fried foods , artificial sweeteners and other highly processed foods , which can decrease microbial diversity .
14 TRITON | FALL 2015