Researchers have found that a common cold virus could be making people obese, several newspapers reported.
Many of the newspapers continued that the research could lead to a vaccine that could combat obesity. The Daily Telegraph led with a headline stating: ‘Vaccine for obesity could be ready within five years’.
Most of the reports quoted the researchers, who had tempered their announcement by saying that a “virus is not the only cause of obesity” and that “not all infected people will develop obesity”.
These stories are based on a press release describing a laboratory study. Little information about the methods, quality and results of the laboratory study were available for this appraisal. This study needs to be published in a scientific journal before any firm conclusions about its findings can be made.
However, as many of the news articles mentioned, the main causes of obesity and being overweight are known to be related to diet and exercise. These are still the main things to be considered when making lifestyle choices.
Where did the story come from?
Associate Professor Nikhil Dhurandar, Dr Magdalena Pasarica and colleagues of Louisiana State University, USA, conducted this research. It was not clear from the information provided in the press release who funded the research.
The study was presented at the 234th meeting of the American Chemical Society, and described in a press release from this conference. The study has not yet been published in a peer-reviewed journal.
What kind of scientific study was this?
The study was an experimental laboratory study.
Limited information about the study methods were available from the press release. The researchers took stem cells from fatty tissue taken from adults having liposuction, and grew these in the lab. They then exposed half the cells to a virus that is known to cause eye and respiratory infections (human adenovirus-36) and did not expose the other half. They then watched what happened to the cells over about a week.
What were the results of the study?
The press report stated that "most" of the stem cells exposed to the virus developed into fat cells, while the stems cells that were not exposed did not.
What interpretations did the researchers draw from these results?
The researchers concluded: “This study provides stronger evidence that some obesity cases may involve viral infections.”
What does the NHS Knowledge Service make of this study?
Only limited information was provided in the press release about this study, therefore it is very difficult to draw any conclusions about its quality. Full publication of this study in a peer-reviewed journal is needed before we come to any firm conclusions about the validity of this study’s findings. At this stage, there are several important factors to bear in mind:
- This was a laboratory study; therefore we cannot say for certain that this virus leads to production of fat cells naturally in the human body.
- We cannot conclude from this study that obesity can be "transmitted" from one person to another by this virus.
- Reporting, as some of the news articles have done, that obesity is linked to "the common cold" or "sore throats" is incorrect: this study has only examined adenovirus-36. There are multiple viral causes of such upper respiratory tract infections, including many other strains of adenovirus, rhinovirus and enterovirus.
- The authors themselves say, “We're not saying that a virus is the only cause of obesity.”
Until we know for certain whether this virus contributes to human obesity, the development of a vaccine is very unlikely. Even if this or other viruses are found to play a role in the development of human obesity, it seems improbable that a vaccine would play as important a role in reducing obesity as diet and exercise.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Guardian, 21 August 2007
The Independent, 21 August 2007
The Daily Telegraph, 21 August 2007
The Sun, 21 August 2007
Daily Mail, 21 August 2007