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   Changing gut bacteria through diet affects brain function, UCLA study shows   
      
   05.29.2013 · Posted in COPD - Anxiety and Depression, copd nutrition   
      
   UCLA newsroom   
      
   UCLA researchers now have the first evidence that bacteria ingested in food   
   can affect brain function in humans. In an early proof-of-concept study of   
   healthy women, they found that women who regularly consumed beneficial   
   bacteria known as probiotics    
   through yogurt showed altered brain function, both while in a resting state   
   and in response to an emotion-recognition task.   
      
   The study, conducted by scientists with UCLA's Gail and Gerald Oppenheimer   
   Family Center for Neurobiology of Stress and the Ahmanson-Lovelace Brain   
   Mapping Center at UCLA, appears in the current online edition of the   
   peer-reviewed journal    
   Gastroenterology.   
      
   The discovery that changing the bacterial environment, or microbiota, in the   
   gut can affect the brain carries significant implications for future research   
   that could point the way toward dietary or drug interventions to improve brain   
   function, the    
   researchers said.   
      
   "Many of us have a container of yogurt in our refrigerator that we may eat for   
   enjoyment, for calcium or because we think it might help our health in other   
   ways," said Dr. Kirsten Tillisch, an associate professor of medicine at UCLA's   
   David Geffen School    
   of Medicine and lead author of the study. "Our findings indicate that some of   
   the contents of yogurt may actually change the way our brain responds to the   
   environment. When we consider the implications of this work, the old sayings   
   'you are what you eat'    
   and 'gut feelings' take on new meaning."   
      
   Researchers have known that the brain sends signals to the gut, which is why   
   stress and other emotions can contribute to gastrointestinal symptoms. This   
   study shows what has been suspected but until now had been proved only in   
   animal studies: that    
   signals travel the opposite way as well.   
      
   "Time and time again, we hear from patients that they never felt depressed or   
   anxious until they started experiencing problems with their gut," Tillisch   
   said. "Our study shows that the gut-brain connection is a two-way street."   
      
   The small study involved 36 women between the ages of 18 and 55. Researchers   
   divided the women into three groups: one group ate a specific yogurt   
   containing a mix of several probiotics -- bacteria thought to have a positive   
   effect on the intestines --    
   twice a day for four weeks; another group consumed a dairy product that looked   
   and tasted like the yogurt but contained no probiotics; and a third group ate   
   no product at all.   
      
   Functional magnetic resonance imaging (fMRI) scans conducted both before and   
   after the four-week study period looked at the women's brains in a state of   
   rest and in response to an emotion-recognition task in which they viewed a   
   series of pictures of    
   people with angry or frightened faces and matched them to other faces showing   
   the same emotions. This task, designed to measure the engagement of affective   
   and cognitive brain regions in response to a visual stimulus, was chosen   
   because previous research    
   in animals had linked changes in gut flora to changes in affective behaviors.   
      
   The researchers found that, compared with the women who didn't consume the   
   probiotic yogurt, those who did showed a decrease in activity in both the   
   insula -- which processes and integrates internal body sensations, like those   
   form the gut -- and the    
   somatosensory cortex during the emotional reactivity task.   
      
   Further, in response to the task, these women had a decrease in the engagement   
   of a widespread network in the brain that includes emotion-, cognition- and   
   sensory-related areas. The women in the other two groups showed a stable or   
   increased activity in    
   this network.   
      
   During the resting brain scan, the women consuming probiotics showed greater   
   connectivity between a key brainstem region known as the periaqueductal grey   
   and cognition-associated areas of the prefrontal cortex. The women who ate no   
   product at all, on the    
   other hand, showed greater connectivity of the periaqueductal grey to emotion-   
   and sensation-related regions, while the group consuming the non-probiotic   
   dairy product showed results in between.   
      
   The researchers were surprised to find that the brain effects could be seen in   
   many areas, including those involved in sensory processing and not merely   
   those associated with emotion, Tillisch said.   
      
   The knowledge that signals are sent from the intestine to the brain and that   
   they can be modulated by a dietary change is likely to lead to an expansion of   
   research aimed at finding new strategies to prevent or treat digestive, mental   
   and neurological    
   disorders, said Dr. Emeran Mayer, a professor of medicine, physiology and   
   psychiatry at the David Geffen School of Medicine at UCLA and the study's   
   senior author.   
      
   "There are studies showing that what we eat can alter the composition and   
   products of the gut flora -- in particular, that people with high-vegetable,   
   fiber-based diets have a different composition of their microbiota, or gut   
   environment, than people who    
   eat the more typical Western diet that is high in fat and carbohydrates,"   
   Mayer said. "Now we know that this has an effect not only on the metabolism   
   but also affects brain function."   
      
   The UCLA researchers are seeking to pinpoint particular chemicals produced by   
   gut bacteria that may be triggering the signals to the brain. They also plan   
   to study whether people with gastrointestinal symptoms such as bloating,   
   abdominal pain and altered    
   bowel movements have improvements in their digestive symptoms which correlate   
   with changes in brain response.   
      
   Meanwhile, Mayer notes that other researchers are studying the potential   
   benefits of certain probiotics in yogurts on mood symptoms such as anxiety. He   
   said that other nutritional strategies may also be found to be beneficial.   
      
   By demonstrating the brain effects of probiotics, the study also raises the   
   question of whether repeated courses of antibiotics can affect the brain, as   
   some have speculated. Antibiotics are used extensively in neonatal intensive   
   care units and in    
   childhood respiratory tract infections, and such suppression of the normal   
   microbiota may have long-term consequences on brain development.   
      
      
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