obesity

Sewage Bacteria Reveal Cities’ Obesity Rates

Urban ‘microbiome’ can offer glimpses into disease trends.

Sampling the waste in a city’s sewage system can be a good way to study the microbes that live in the population’s guts – and could even offer a way to monitor public health issues such as obesity, according to new research.

The community of microbes that live in a person’s gut, known as the microbiome, is intricately tied to that person’s health. The microbiome can influence, and be influenced by, a range of characteristics such as weight, disease, diet, exercise, mood and much more. But it can be difficult to draw large-scale conclusions about what constitutes a “healthy gut” because of the financial and privacy implications of sampling large enough numbers of people.

So a team of researchers led by Sandra McLellan at the University of Wisconsin-Milwaukee and Mitchell Sogin at the Marine Biological Laboratory in Woods Hole, Massachusetts, set out to test whether they would be able to spot human microbes lurking in the soupy mix of municipal sewage systems, and thus sample entire cities at once. Read more at Inside Science.

Exercise prescriptions endorsed

IMG_6714Doctors in two Canadian provinces are using exercise prescription pads to encourage patients to lead healthier, more active lifestyles. Doctors of BC (British Columbia) and the New Brunswick Medical Society (NBMS) offer free pads to their members so they can give patients a physical reminder of the exercise advice they’ve been given by their physicians.

Dr. Lynn Hansen, president of NBMS, said the pads are intended to help patients stick to their exercise regimes. “If they have something in writing, it provides a more permanent reminder of the conversation they had with their doctor,” she said. “We know not everything that is said in the doctor’s office is retained.” Read more in CMAJ.

Dietary fibre acts on brain to suppress appetite

Mouse study suggests that brain activity, not gut hormones, accounts for fibre’s weight-control action.

People have long been told that a diet high in fibre can help to fight obesity, but how it does so has been unclear. A study of mouse metabolism now suggests that a product of fibre fermentation may be directly affecting the hypothalamus, a region of the brain involved in regulating appetite. Read more in Nature.

The changing colour of fat

The different functions of white, brown and beige fat might yield new targets in the fight against obesity and metabolic disease.

When you think of fat in the human body, you might picture a homogenous, white substance, much like a block of lard. But researchers are learning that the role of fat in metabolism changes depending on where it is in the body, and even on the type of fat cell. Soon these differences could be harnessed to fight metabolic disorders such as diabetes and obesity. Read more in Nature.

New contender for ‘fat gene’ found

Researchers may have been focusing on the wrong gene.

Scientists studying what they thought was a ‘fat gene’ seem to have been looking in the wrong place, according to research published today in Nature. It suggests instead that the real culprit is another gene that the suspected obesity gene interacts with.

In 2007, several genome studies identified mutations in a gene called FTO that were strongly associated with an increased risk of obesity and type 2 diabetes in humans. Subsequent studies in mice showed a link between the gene and body mass. So researchers, including Marcelo Nóbrega, a geneticist at the University of Chicago, thought that they had found a promising candidate for a gene that helped cause obesity. Read more in Nature.

Storm brewing over WHO sugar proposal

Industry backlash expected over suggested cut in intake.

Scientists are gearing up for a battle with the food industry after the World Health Organization (WHO) moved to halve its recommendation on sugar intake.

Nutrition researchers fear a backlash similar to that seen in 2003, when the WHO released its current guidelines stating that no more than 10% of an adult’s daily calories should come from ‘free’ sugars. That covers those added to food, as well as natural sugars in honey, syrups and fruit juice. In 2003, the US Sugar Association, a powerful food-industry lobby group based in Washington DC, pressed the US government to withdraw funding for the WHO if the organization did not modify its recommendations. The WHO did not back down, and has now mooted cutting the level to 5%. Read more in Nature.

Bacteria from lean mice prevents obesity in peers

But microbes are only part of the story — the effect also depends on a healthy diet.

Gut bacteria from lean mice can invade the guts of obesity-prone cage-mates and help their new hosts to fight weight gain.

Researchers led by Jeffrey Gordon, a biologist at Washington University in St. Louis, Missouri, set out to find direct evidence that gut bacteria have a role in obesity.

The team took gut bacteria from four sets of human twins in which one of each pair was lean and one was obese, and introduced the microbes into mice bred to be germ-free. Mice given bacteria from a lean twin stayed slim, whereas those given bacteria from an obese twin quickly gained weight, even though all the mice ate about the same amount of food. Read more in Nature.

Heavy sleepers

A growing body of evidence shows that getting a good night’s sleep plays an important role in regulating the body’s metabolism.

Burning the midnight oil can leave you tired and grumpy the next day, dulling your mind and slowing your reaction times. But lack of sleep has consequences beyond the brain as well, with long-term sleep disturbances leading to metabolic problems.

Matthew Brady, a biologist at the University of Chicago in Illinois who studies the links between sleep and metabolism, puts it simply: “Fat cells need their sleep as well.” Read more in Nature.

Gut microbe may fight obesity and diabetes

Bacterium helps to regulate metabolism in mice.

The gut is home to innumerable different bacteria — a complex ecosystem that has an active role in a variety of bodily functions. In a study published this week in Proceedings of the National Academy of Sciences, a team of researchers finds that in mice, just one of those bacterial species plays a major part in controlling obesity and metabolic disorders such as type 2 diabetes.

The bacterium, Akkermansia muciniphila, digests mucus and makes up 3–5% of the microbes in a healthy mammalian gut. But the intestines of obese humans and mice, and those with type 2 diabetes, have much lower levels. A team led by Patrice Cani, who studies the interaction between gut bacteria and metabolism at the Catholic University of Louvain in Belgium, decided to investigate the link. Read more in Nature.