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NHS Choices: Behind the headlines   + / -  
last updated: Tue, 27 Sep 2016 16:33:26 GMT

 Tue, 27 Sep 2016 14:00:00 GMT Could riding roller coasters help you pass kidney stones?

"Got kidney stones? Ride a roller coaster! Study shows it is the most pain-free cost-efficient way to pass them," says the Mail Online of a study carried out in the US which tested riding roller coasters as a way of passing kidney stones.

The study came about after a number of people with kidney stones claimed riding on Walt Disney World's Big Thunder Mountain Railroad ride had helped them pass their stones. In particular, one person with kidney stones reported passing a stone after each of three consecutive rides. This prompted a research team from Michigan State University, led by Dr David Wartinger, to investigate further.

The researchers rode the Big Thunder Mountain Railroad ride a total of 60 times carrying a 3D printed model kidney made from silicone. The kidney contained urine and kidney stones of three different sizes.

They found that the rides caused the kidney stones to be passed from the kidney, and that the position on the ride made a big difference to the number of stones passed. Sitting at the back of the ride produced the best results.

A key limitation of the study is that the research was carried out on a model kidney rather than on the kidneys of real people. This method can never truly replicate the behaviour of the stones in a real kidney. However, the findings may support the case for further research into what it is about the ride that might cause stones to pass.

Where did the story come from?

The study was carried out by researchers from Michigan State University, who reported no source of funding for the study. 

The report was published in the peer-reviewed Journal of the American Osteopathic Association.

The Mail Online and The Daily Telegraph presented the main findings of the study but fail to mention any of the limitations of the research.

What kind of research was this?

This was an experimental study which aimed to assess roller coaster rides as a method of passing kidney stones.

Kidney stones are formed when certain chemicals, usually calcium, or uric acid, build up in the body. Some medical conditions can contribute to high levels of these substances being in the body. They are more likely if you don't drink enough fluids.

This study is able to provide possible links for further investigation but can't provide any conclusive evidence that would be applicable to all. The study team appreciate this limitation and were reported in the Mail Online as saying: "The purpose of this initial study was to validate the effectiveness of the model and support the case for further research."

What did the research involve?

The researchers aimed to assess the effectiveness of roller coaster rides for passing kidney stones by creating an anatomical model of the kidney and taking this on a number of rides to test various scenarios of stone position within the kidney and different seating positions on the ride.

The roller coaster, Walt Disney World's Big Thunder Mountain Railroad ride, had a maximum speed of 35mph, took sharp turns and had quick drops. The ride did not go upside down and lasted for two and a half minutes.

The model itself was made of clear silicone to allow direct inspection of the stone location after each ride and was based on the kidney scan of the patient providing the kidney stones for the test.

The stones were suspended in urine within the model and were of three different volumes:

  • 4.5 mm3
  • 13.5 mm3
  • 64.6 mm3

The model was placed in a padded backpack that was positioned at kidney height at the back of the seat on the roller coaster, between the researchers. Data was gathered 20 times for each of the kidney chambers, eight rides in the front seating and 12 in the rear seating. 

What were the basic results?

Sixty roller coaster rides were taken and the effect on the kidney stones analysed.

When the model was carried in the front seating of the roller coaster fewer kidney stones were passed (16.7%) than when sat in the rear seating (63.9%).

The position of the stone also appears to make a difference to the rate of passage. If the stone is in the upper chambers (calyces) of the kidney it is passed more frequently than when it is in the middle or lower chambers. In fact, when the model was carried in the rear of the roller coaster, stones in the upper chamber were passed 100% of the time. 

The size of the stone did not appear to influence the proportion of stones passed.

How did the researchers interpret the results?

The researchers concluded that their model served as a functional patient surrogate to evaluate activities that facilitate the passing of kidney stones. In other words, they could expect the kidneys and kidney stones of real people to behave in the same way as the model. They state that the rear seating position on the roller coaster led to the most kidney stones being passed.

Conclusion

This experimental study assessed going on roller coasters as a means of passing kidney stones.

Prior to this study there had been a number of reports that riding on roller coasters had caused people to pass their kidney stones, with one person claiming to have passed three kidney stones after three consecutive rides on the Big Thunder Mountain Railroad roller coaster at Disney World in Florida.

The researchers found a similar effect using their model, and also saw that the seating position on the ride made a big difference, with almost four times the number of stones passing in the rear of the ride compared to the front.

There are a number of limitations to this research:

  • The study used an anatomical model of the kidney rather than actual people. This will never truly replicate the behaviour of the stones in a real kidney.
  • The model was based on a single person with kidney stones. The anatomy of this person's kidney will not be the same as other peoples' because the anatomy of an individual's kidneys is unique, much like a fingerprint.
  • Only a single roller coaster was used. The same effect may not be seen on other rides with different characteristics.

However, as the research team told the media, this was an initial study to validate the effectiveness of the model and support the case for further research.

Some symptoms of kidney stones to be aware of are:

  • a persistent ache in the lower back
  • periods of intense pain in the back or side of your abdomen
  • feeling sick
  • needing to urinate more often than normal
  • pain when you urinate
  • blood in your urine 

To prevent kidney stones make sure you avoid becoming dehydrated. Drinks such as tea, coffee and fruit juice can count towards your fluid intake, but water is the healthiest option and is best for preventing kidney stones developing. Make sure you drink more when it is hot or when you are exercising, to replenish fluids lost through sweating.

Links To The Headlines

Got kidney stones? Ride a roller coaster! Study shows it is the most pain-free cost-efficient way to pass them Mail Online, September 26 2016

Roller coasters could be a cure for kidney stones The Telegraph, September 26  2016

 

Links To Science

Mitchell, Marc A, Wartinger, David D Validation of Functional Pyelocalyceal Renal Model for the Evaluation of Renal Calculi Passage While Riding a Roller Coaster. The Journal of the American Osteopathic Association. Published online September 2016

 Mon, 26 Sep 2016 00:00:00 GMT Gut bacteria may be linked to 'dangerous' body fat

The BBC reports that: "The make-up of the bacteria found in human faeces may influence levels of dangerous fat in our bodies."

The article is based on a UK study looking at faeces samples taken from twins, and various measures of obesity. The study showed that people who had fewer different types of bacteria in their faeces were more likely to be obese.

The link was strongest for visceral fat, which is stored around the internal organs inside the abdominal cavity. This type of fat is associated with a higher risk of metabolic diseases, such as type 2 diabetes, as well as cardiovascular disease.

The study also found that identical twins were more likely to have similar diversity of bacteria in their faeces than non-identical twins, suggesting it may be partly inherited. This could explain why obesity sometimes passes down through families.

While there's a clear link between bacteria in faeces and visceral fat, it's not yet known how the diversity and type of bacteria influences body fat. Further research is needed.

Eating a balanced diet and having an active lifestyle can help you maintain a healthy weight.

Where did the story come from?

The study was carried out by researchers from the Department of Twin Research and Genetic Epidemiology at King's College London in the UK, the Department of Microbiology and the Department of Molecular Biology and Genetics at Cornell University, and the University of Colorado in the US, and the Max Planck Institute for Developmental Biology in Germany. 

It was funded by the US National Institutes for Health (NIH), the Cornell Center for Comparative Population Genomics, the Wellcome Trust, the European Community's Seventh Framework Programme, the European Research Council, and the National Institute for Health Research (NIHR).

The authors declared no conflicts of interest.

The study was published in the peer-reviewed journal, Genome Biology. It is open access, so it's freely available to read online.

The media reported the story accurately, with the BBC acknowledging that, although there is a link between bacteria in human faeces and levels of obesity, there is no known explanation yet.

What kind of research was this?

This was a cross-sectional observational study carried out on healthy sets of twins.

It aimed to explore the association between the bacteria present in human faeces and obesity.

This type of study can't prove cause and effect, but is useful for looking at associations between risk factors and outcomes.

So while this study doesn't prove that bacteria found in human faeces cause visceral fat, it does show there is a relationship between the two.

What did the research involve?

Researchers studied healthy volunteers involved in the TwinsUK Adult Twin Registry. Data on body fat was collected from a sample of 3,666 twins.

They looked at the links between bacteria found in faeces and six different measures of body fat.

The sample was mostly of European descent, and the average age was 63.

Faeces samples were collected from 1,313 individuals, and the bacteria in these investigated. Almost all those sampled were female.

The information from study participants on the bacteria present in their faeces was compared with body fat levels.

The six body fat measures included three of visceral fat, two of body fat distribution, and one of body mass index (BMI).

Excess visceral fat in particular is a risk factor for cardiovascular disease and metabolic disease, such as type 2 diabetes.

What were the basic results?

All but one measure of obesity were significantly associated with a lack of diversity of bacteria in the faeces.

However, the association was strongest for visceral fat, which is found around the internal organs and is a bigger risk factor for cardiovascular and metabolic diseases.

Researchers found the higher the diversity of bacteria in faeces, the lower the level of visceral fat.

The reverse was also shown: the less diverse the bacteria, the more likely participants were to have more visceral fat.

Visceral fat was found to be highly heritable (relative risk [RR] = 0.70, 95% confidence interval [CI] = 0.58 to 0.74). This was true even when adjustments for body mass index (BMI) were made.

How did the researchers interpret the results?

Dr Michelle Beaumont, lead author of the study from the Department of Twin Research and Genetic Epidemiology at King's, said: "This study has shown a clear link between bacterial diversity in faeces and markers of obesity and cardiovascular risk, particularly for visceral fat.

"However, as this was an observational study we cannot say precisely how communities of bacteria in the gut might influence the storage of fat in the body, or whether a different mechanism is involved in weight gain."

Senior author, Dr Jordana Bell, also from the Department of Twin Research and Genetic Epidemiology, said: "There is a growing body of evidence to suggest that gut bacteria may play a role in obesity, and a number of studies are now exploring this in more detail.

"Further scientific investigation is needed to understand how precisely our gut microbes can influence human health, and if interventions such as faecal transplants can have safe, beneficial, and effective impacts on this process."

Conclusion

This cross-sectional study found a strong association between visceral fat and bacteria diversity in faeces.

The use of measures other than BMI was one of this study's strengths, as BMI doesn't reveal whether weight is from fat tissue or muscle.

The findings suggest that body fat levels may be passed down through families.

However, this is early research and there are a number of things to consider:

  • We don't know how the bacteria in our gut and faeces influence levels of fat in the body.
  • The study doesn't prove that having less diverse bacteria in our faeces causes visceral fat around the organs.
  • Participants' diets weren't taken into consideration.
  • Participants were mainly female and from the UK, so the findings can't be applied across genders or globally.

It's important to eat a balanced diet and have an active lifestyle to maintain a healthy weight.

Links To The Headlines

Body fat link to bacteria in faeces. BBC News, September 26 2016

How gut bacteria may predict belly fat. Time, September 25 2016

Links To Science

Beaumont M, Goodrich J, Jackson M. Heritable components of the human fecal microbiome are associated with visceral fat. Genome Biology. Published 26 September 2016

 Fri, 23 Sep 2016 16:28:00 GMT Fitness trackers 'don't help you lose weight'

"Fitness trackers may not help weight loss," reports Sky News on a new trial which investigated whether using wearable technology helped people lose more weight compared to standard weight-loss programmes.

Researchers tracked 470 overweight or obese people aged 18 to 35, for 24 months. Everyone in the study was put on a low-calorie diet, given an exercise plan and invited to regular group counselling sessions.

After six months, half the group was given a wearable device to track activity and feed it into a computer programme that also allows people to record their diet.

The other half were simply told to continue the weight loss programme and monitor their exercise and diet by themselves.

The group using the Fit Core tracker lost an average of 3.5kg over two years, compared with an average 5.9kg in the self-monitored group.

The spread of obesity across the globe has been increasing rapidly in recent years and public health bodies continue to struggle with tackling the issue.

Along with the usual weight-loss diets, the use of wearable technologies promoting fitness, such as FitBit and Jawbone, is also on the rise.

The study authors say there are many possible explanations for their surprising finding but, as yet, no proof.

BBC News quotes lead researcher Dr John Jakicic saying: "People have a tendency to use gadgets like these for a while and then lose interest with time as the novelty wears off.

"And we did see a drop off in the usage data as the study went on."

Although the study's findings are interesting, it may be the case that the use of fitness trackers and other devices may be more effective for some people than others.

Until more conclusive research is available, the best advice for losing weight is to follow a calorie-controlled diet combined with regular exercise.

Where did the story come from?

The study was carried out by researchers from the University of Pittsburgh in the US. It was funded by a grant from the National Institutes of Health and the National Heart, Lung and Blood Institute.

Interestingly, the researchers were affiliated with Weight Watchers International.

The findings from the trial were published in the peer-reviewed medical journal JAMA. It is free to read online.

Generally, media coverage around this topic was accurate.

What kind of research was this?

This was a randomised controlled trial (RCT) which aimed to compare the effectiveness of a wearable technology weight loss intervention (fitness tracker) with standard weight loss strategies to see which would result in greater weight loss.

RCTs such as this are one of the best ways to investigate the effectiveness of public health interventions.

In such trials there is the possibility that the individuals' knowledge of being monitored by the wearable technology could influence their diet, activity and weight loss. This is known as being non-blinded to the intervention group, which can normally be a potential source of study bias. However, in this case it's probably just part of the way the intervention was intended to work.

What did the research involve?

The 24-month Innovative Approaches to Diet, Exercise and Activity (IDEA) randomised controlled trial at the University of Pittsburgh recruited 471 participants (aged 18-35) with a body mass index (BMI) between 25.0 and 40.0.

Participants were randomised to one of two treatment groups: a standard behavioural weight loss intervention and a weight loss intervention enhanced by using wearable technology.

For the first six months both groups received the same behavioural weight loss intervention and were instructed to self-monitor dietary intake and their physical activity in diaries. This information was given to the study staff who offered feedback.

At six months, the standard behavioural weight loss group started self-monitoring their diet and physical activity via an website designed for the trial. No feedback was given. At this time, the enhanced intervention group were given their wearable technology device which had access to education materials via a web-based interface (BodyMedia FIT Core). This monitored their diet and physical activity.

During months 7-24, both groups also received telephone counselling sessions, text message prompts and access to online study materials.

The main outcome of the study was to assess weight change at 24 months. Participants were also assessed at months 0, 6, 12 and 18, and received monetary compensation for completing each assessment. The researchers analysed the findings between both treatment groups.

What were the basic results?

Overall, there was significant weight change over time in both treatment groups. However, there was greater weight loss in the standard behavioural intervention group compared with the technology-enhanced intervention.

  • The average weight loss between baseline and 24 months in the standard behavioural intervention group was 5.9kg (95% confidence interval (CI): 5.0 to 6.8).
  • In the technology-enhanced intervention group, the average weight loss over the same time was 3.5kg (95% CI: 2.7 to 4.5).
  • The difference between the two groups was 2.4kg (95% CI: 1.0 to 3.7).

Additionally, there was a greater decrease in body fat (%) in the standard behavioural intervention group compared with the technology-enhanced intervention.

  • The average loss of body fat (%) between baseline and 24 months in the standard intervention was 3.5% (95% CI: -4.0 to –3.0).
  • The enhanced intervention group lost on average 2.4% body fat (95% CI: -3.0 to -1.9).
  • The difference between the two groups was -1.1% in body fat (95% CI: -1.9 to -0.3).

How did the researchers interpret the results?

Researchers concluded: "Among young adults with a BMI between 25 and less than 40, the addition of a wearable technology device to a standard behavioural intervention resulted in less weight loss over 24 months. Devices that monitor and provide feedback on physical activity may not offer an advantage over standard behavioural weight loss approaches."

Conclusion

This trial aimed to compare the effectiveness of a wearable technology weight loss intervention (fitness tracker) with standard weight loss strategies to see which would result in greater weight loss at the end of 24 months.

It found the addition of a wearable technology device did not aid weight loss, and participants in the standard behavioural intervention group lost more weight when compared to the technology group.

This was an interesting study with a reliable study design. However there are a few things to note:

  • As the authors mention, the participants were all young adults (mean age 30) and 77.2% were women so these findings are not representative of the general population.
  • Although this trial showed weight loss over a 24 month period, the greatest weight loss was achieved in the first six months and this was not fully sustained over the long-term. Therefore, the challenges of maintaining weight loss continue to exist.
  • The adoption of the wearable technology device was started six months into the intervention so the findings may have been different had the participants started using them at baseline.

Links To The Headlines

Fitness trackers offer no weight-loss benefit and can make users fatter, says study. The Daily Telegraph, September 21 2016

'No proof' fitness trackers promote weight loss. BBC News, September 20 2016

Fitness trackers may not help weight loss. Sky News, September 21 2016

Fitness trackers may not aid weight loss, study finds. The Guardian, September 21 2016

Study finds fitness trackers don't pull their weight. The Daily Mail, September 21 2016

Links To Science

Jakicic JM, Davis KK, Rogers RJ et al. Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight Loss: The IDEA Randomized Clinical Trial. Published September 21 2016


 

 
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