Diet Quickly Alters Gut Bacteria

A New Diet Quickly Alters Gut Bacteria:

 

A New Diet Quickly Alters Gut Bacteria

A New Diet Quickly Alters Gut BacteriaGut clock regulates when we’re hungry

 

The types of bacteria in your gut today may be different tomorrow, depending on what kinds of food you eat, a new study suggests.

In the study, participants who switched from their normal diet to eating only animal products, including meat, cheese and eggs, saw their gut bacteria change rapidly — within one day.

While the participants were on the animal-based diet, there was an increase within their guts in the types of bacteria that can tolerate bile (a fluid produced by the liver that helps break down fat), and a decrease in bacteria called Firmicutes, which break down plant carbohydrates.

 

Gut bacteria also tended to express (or “turn on”) different genes during the animal-based diet, ones that would allow them to break down protein. In contrast, the gut bacteria of another group of participants who ate a plant-based diet expressed genes that would allow them to ferment carbohydrates.

The differences between the gut bacteria of the people on the plant-only and animal-only diets “mirrored the differences between herbivorous and carnivorous mammals,” the researchers wrote in the study published today (Dec. 11) in the journal Nature.

Researchers knew that a person’s diet affects his or her gut bacteria, but it wasn’t clear just how quickly this happens.

The researchers said they were surprised by their results. “We weren’t at all sure it was going to happen this quickly in humans,” said study researcher Lawrence David, an assistant professor at Duke University’s Institute for Genome Sciences and Policy.

The findings suggest “the choices that people make on relatively short time scales … could be affecting the massive bacterial communities that live inside of us,” David said.

The study also adds evidence to the idea that human diets — acting through the gut bacteria — influence the risk of certain diseases. People on the animal-based diet had higher levels of a bacterium called Bilophila wadsworthia, which grows in response to bile acids and has been linked with inflammatory bowel disease in mice, according to the study.

This finding supports a link between dietary fat (from animal fat), bile acids and an increase in growth of microbes that may affect the risk of inflammatory bowel disease, the researchers said.

People who ate the plant-based diet saw fewer changes in the abundance of bacterial species in their gut than people who ate the animal-based diet. This may have, in part, been due to the fact that humans produce bile acids in response to eating animal products, and bile acids, in turn, influence bacterial growth, according to the researchers.

The study included 10 people (six men and four women) ages 21 to 33. One of the participants was a lifelong vegetarian who switched to eating only animal products, such as eggs and cheese (but not meat), for the study. Participants stuck to their diet for five days, and gave stool samples each day for analysis.

While previous studies have looked at changes in gut bacteria in response to diet, most of these collected samples on a weekly or monthly basis, because it is difficult to recruit volunteers willing to give samples daily, David said.

Because the study was small, the researchers are cautious about generalizing their results to the population as a whole. But “the changes we saw appeared to be uniform across these subjects, suggesting that if we were to recruit more people, we would see similar results,” David said.

The study was a collaboration between researchers at Duke, Harvard University, Boston Children’s Hospital and the University of California, San Francisco.

Brain Parasite Alters Brain Chemistry

Brain Parasite Directly Alters Brain Chemistry – T gondii Affects Dopamine:

Toxoplasma gondii

Toxoplasma gondii

A research group from the University of Leeds has shown that infection by the brain parasite Toxoplasma gondii, found in 10-20 per cent of the UK’s population, directly affects the production of dopamine, a key chemical messenger in the brain. Their findings are the first to demonstrate that a parasite found in the brain of mammals can affect dopamine levels. Whilst the work has been carried out with rodents, lead investigator Dr Glenn McConkey of the University’s Faculty of Biological Sciences, believes that the findings could ultimately shed new light on treating human neurological disorders that are dopamine-related such as schizophrenia, attention deficit hyperactivity disorder, and Parkinson’s disease. This research may explain how these parasites, remarkably, manipulate rodents’ behaviour for their own advantage. Infected mice and rats lose their innate fear of cats, increasing the chances of being caught and eaten, which enables the parasite to return to its main host to complete its life cycle. In this study, funded by the Stanley Medical Research Institute and Dunhill Medical Trust, the research team found that the parasite causes production and release of many times the normal amount of dopamine in infected brain cells. Dopamine is a natural chemical which relays messages in the brain controlling aspects of movement, cognition and behaviour. It helps control the brain’s reward and pleasure centres and regulates emotional responses such as fear. The presence of a certain kind of dopamine receptor is also associated with sensation-seeking, whereas dopamine deficiency in humans results in Parkinson’s disease. These findings build on earlier studies in which Dr McConkey’s group found that the parasite actually encodes the enzyme for producing dopamine in its genome. “Based on these analyses, it was clear that T. gondii can orchestrate a significant increase in dopamine production in neural cells,” says Dr McConkey. “Humans are accidental hosts to T. gondii and the parasite could end up anywhere in the brain, so human symptoms of toxoplasmosis infection may depend on where parasite ends up. This may explain the observed statistical link between incidences of schizophrenia and toxoplasmosis infection.” Dr McConkey says his next experiments will investigate how the parasite enzyme triggers dopamine production and how this may change behaviour.