Latest News & Research: 9 July 2019

This week: Adding ‘elite athlete bacteria’ to sedentary people enhances performance • Young people engaging in ‘disordered eating’ to bulk up • Could coffee be an instrument for fighting obesity?

 

Adding ‘elite athlete bacteria’ to sedentary people enhances performance

New research has identified a type of bacteria found in the microbiomes of elite athletes that contributes to improved capacity for exercise. These bacteria, members of the genus Veillonella, are not found in the guts of sedentary people.

By taking a closer look at the bacteria, the researchers from Joslin Diabetes Center determined Veillonella metabolises lactic acid produced by exercise and converts it into propionate, a short chain fatty acid. The human body then utilises that propionate to improve exercise capacity. The results were reported in Nature Medicine.

‘Having increased exercise capacity is a strong predictor of overall health and protection against cardiovascular disease, diabetes, and overall longevity’ said Aleksandar Kostic PhD, Assistant Investigator in the Section on Pathophysiology and Molecular Pharmacology and a co-author of the paper; ‘What we envision is a probiotic supplement that people can take that will increase their ability to do meaningful exercise and therefore protect them against chronic diseases including diabetes.’

The work began in 2015 with fecal samples from Boston Marathon runners. Jonathan Scheiman, PhD, then a researcher in the lab of George Church, PhD, at Harvard Medical School, collected samples during a time span of one week before the marathon to one week after the marathon. He also collected samples from sedentary individuals. Scheiman then brought the samples to Kostic, who analysed them to determine the species of bacteria in both cohorts.

‘One of the things that immediately caught our attention was this single organism, Veillonella, that was clearly enriched in abundance immediately after the marathon in the runners. Veillonella is also at higher abundance in the marathon runners [in general] than it is in sedentary individuals’ said Kostic.

They confirmed the link to improved exercise capacity in mouse models, where they saw a marked increase in running ability after supplementation with Veillonella. Next, they wanted to figure out how it worked.

‘As we dug into the details of Veillonella, what we found was that it is relatively unique in the human microbiome in that it uses lactate or lactic acid as its sole carbon source’ he said.

Lactic acid is produced by the muscles during strenuous exercise. The Veillonella bacteria are able to use this exercise by-product as their main food source.

‘Our immediate hypothesis was that it worked as a metabolic sink to remove lactate from the system, the idea being that lactate build-up in the muscles creates fatigue’ he said; ‘But talking to people like Sarah Lessard, [a clinical researcher at Joslin] and other people in the exercise physiology field, apparently this idea that lactate build-up causes fatigue is not accepted to be true. So, it caused us to rethink the mechanism of how this is happening.’

Kostic and his team returned to the lab to figure out what could be causing the increase in exercise capacity. They ran a metagenomic analysis, meaning they tracked the genetics of all the organisms in the microbiome community, to determine what events were triggered by Veillonella’s metabolism of lactic acid. They noted that the enzymes associated with conversion of lactic acid into the short chain fatty acid propionate were at much higher abundance after exercise.

‘Then the question was maybe it's not removal of lactic acid, but the generation of propionate’ said Kostic; ‘We did some experiments to introduce propionate into mice [via enema] and test whether that was sufficient for this increased running ability phenotype. And it was.’

 Kostic and his team plan to investigate the mechanisms of how propionate affects exercise capacity in a collaboration with Lessard. Colonies of bacteria residing in our guts have a powerful impact on our health. Exercise is an important component of a healthy lifestyle meant to ward off diseases such as type 2 diabetes. Many people with metabolic disorders are not able to exercise at the level needed to see such benefits. Supplementing their microbiome using a probiotic capsule containing Veillonella could give them the boost they need for effective exercise. (Direct dosing with propionate pill would not work, as the short chain fatty acid would be broken down by digestive juices before it could take effect.) Scheiman has since spun this idea off into a company targeted at athletes.

‘The microbiome is such a powerful metabolic engine’ said Kostic. This is one of the first studies to directly show a strong example of symbiosis between microbes and their human host.

‘It's very clear. It creates this positive feedback loop. The host is producing something that this particular microbe favours. Then in return, the microbe is creating something that benefits the host’ he said; ‘This is a really important example of how the microbiome has evolved ways to become this symbiotic presence in the human host.’

Source: Joslin Diabetes Center



Young people engaging in ‘disordered eating’ to bulk up

Adolescents who see themselves as puny and who exercise to gain weight may be at risk of so-called muscularity-oriented disordered eating behaviours, according to research led by University of California San Francisco’s Benioff Children’s Hospitals.

The researchers found that 22% of males and 5% of females ages 18-to-24 exhibit these disordered eating behaviors, which are defined as including at least one of the following: Eating more or differently to gain weight or bulk up, and use of dietary supplements or anabolic steroids to achieve the same goal.
Left unchecked, these behaviours may escalate to muscle dysmorphia, characterised by rigid diet, obsessive over-exercising and extreme preoccupation with physique, say the researchers in their study published in the International Journal of Eating Disorders on June 20, 2019.

‘Some eating disorders can be challenging to diagnose’ said first author Jason Nagata, MD, of the UCSF Division of Adolescent and Young Adult Medicine; ‘Unlike anorexia nervosa, which may be easily identified by parents or pediatricians, disordered eating to increase bulk may masquerade as healthy habits and because of this, it tends to go unnoticed.’

At its most extreme, it can lead to heart failure due to insufficient calories and overexertion, as well as muscle dysmorphia, which is associated with social withdrawal and depression, Nagata said.

The 14,891 young adults in the study, from throughout the US, had been followed for seven years. The researchers wanted to see if the early data, when the participants’ average age was 15, revealed something about their perceptions and habits that may serve as warning signs.

They found that boys who exercised specifically to gain weight had 142% higher odds of this type of disordered eating; among girls, the odds were increased by 248%. Boys who perceived themselves as being underweight had 56% higher odds; in girls the odds were 271% higher. Smoking and alcohol use in boys, and smoking in girls, increased odds moderately.

Additionally, being of black race bolstered odds by 66% in boys and 181% in girls.

Non-heterosexual identity, which the participants had been asked about when they reached adulthood, was not found to be a risk factor, the researchers said.

In young adulthood, 6.9% of males reported supplement use to gain weight or build muscle and 2.8% said they used anabolic steroids. Use by young women was significantly lower at 0.7% and 0.4% respectively.

‘Supplements are a black box, since they are not regulated’ noted Nagata; ‘In extreme cases, supplements can cause liver and kidney damage. Anabolic steroids can cause both long-term and short-term health issues, including shrunken testicles, stunted growth and heart disease.’

Nagata said that clues that indicate behaviours may approach muscle dysmorphia include a highly restrictive diet that omits fats and carbohydrates, compulsive weighing and checking of appearance, and extensive time dedicated to exercise that may cut into social activities.

Source: University of California San Francisco



Could coffee be an instrument for fighting obesity?

Scientists from the University of Nottingham have discovered that drinking a cup of coffee can stimulate ‘brown fat’, the body’s own fat-fighting defences, which could be the key to tackling obesity and diabetes.

The study, published in the journal Scientific Reports, is one of the first to be carried out in humans to find components which could have a direct effect on ‘brown fat’ functions, an important part of the human body which plays a key role in how quickly we can burn calories as energy.

Brown adipose tissue (BAT), also known as brown fat, is one of two types of fat found in humans and other mammals. Its main function is to generate body heat by burning calories (as opposed to white fat, which is a result of storing excess calories).

People with a lower body mass index (BMI) therefore have a higher amount of brown fat.
Professor Michael Symonds, from the School of Medicine at the University of Nottingham who co-directed the study, said; ‘Brown fat works in a different way to other fat in your body and produces heat by burning sugar and fat, often in response to cold. Increasing its activity improves blood sugar control as well as improving blood lipid levels and the extra calories burnt help with weight loss. However, until now, no one has found an acceptable way to stimulate its activity in humans.

‘This is the first study in humans to show that something like a cup of coffee can have a direct effect on our brown fat functions. The potential implications of our results are pretty big, as obesity is a major health concern for society and we also have a growing diabetes epidemic and brown fat could potentially be part of the solution in tackling them.’

The team started with a series of stem cell studies to see if caffeine would stimulate brown fat. Once they had found the right dose, they then moved on to humans to see if the results were similar. The team used a thermal imaging technique, which they’d previously pioneered, to trace the body’s brown fat reserves. The non-invasive technique helps the team to locate brown fat and assess its capacity to produce heat.

‘From our previous work, we knew that brown fat is mainly located in the neck region, so we were able to image someone straight after they had a drink to see if the brown fat got hotter’ said Symonds; ‘The results were positive and we now need to ascertain that caffeine as one of the ingredients in the coffee is acting as the stimulus or if there’s another component helping with the activation of brown fat. We are currently looking at caffeine supplements to test whether the effect is similar. Once we have confirmed which component is responsible for this, it could potentially be used as part of a weight management regime or as part of glucose regulation program to help prevent diabetes.’

Source: The University of Nottingham