Monday July 9 2012
A vaccine for obesity is still the stuff of fantasy
A “flab jab” that gets our immune systems to fight weight gain could let us “stay slim on a junk food diet”, the Daily Mail has reported, along with much of the rest of the national press. The Mail added that “mice given a single injection lost 10 per cent of body weight after four days”.
Sadly for people seeking a weight-loss quick fix, on closer inspection the Mail’s claims are a little hard to swallow. The jabs described are designed to block the effects of a hormone called somatostatin, which has many different functions in the body. The news is based on a recent study that looked at the effect of two new anti-somatostatin vaccinations on mice fed a high-fat diet.
What the news stories do not make clear is that:
- Mice who were given the vaccines experienced an initial drastic loss of weight but then gained weight over the course of six weeks – just not as quickly as the mice in the control group.
- The weight loss after the first dose of vaccine was so drastic that the dose used in the second injection in the study was reduced out of concern for the mice’s health.
- If the volume of vaccine given to the mice was scaled up it would be equivalent to over a litre for an average sized adult – a much greater volume than is usually used in a vaccination.
Overall, these results are not hugely encouraging, and the misleading nature of the news reporting is cause for dismay. These vaccinations are not ready for human testing. A treatment that allows people to continue to eat whatever they like and not gain weight is nothing more than fantasy. Furthermore, the suggestion that people can have a jab and then eat as much junk food as they like is dangerous. A poor diet can contribute to a host of diseases, including cancer.
Where did the story come from?
The study was carried out by one researcher who is also the president and chief scientific officer of a company called Braasch Biotech LLC. Braasch Biotech LLC specialises in the development of human and animal vaccines. It is therefore necessary to view the findings with caution, because as a general rule there can be a conflict of interest when reporting findings that might be of personal financial benefit. See How to read the health news for more on this.
The researcher reported that the study was not supported by public funds or other grants. The study was published in the peer-reviewed Journal of Animal Science and Biotechnology.
The media coverage of this story made the results sound much more promising than they are and failed to point out the less positive findings or the flaws in this “flab jab” research.
What kind of research was this?
This was animal research looking at the effects of novel vaccines on weight gain and loss in mice. These vaccines targeted the hormone somatostatin, which inhibits the release of growth hormone. The researcher reported that the growth hormone has been found to have “positive effects on obesity” in animal models of obesity and human studies. Therefore the researcher was interested in finding out if blocking somatostatin could reduce obesity in mice.
Animal research such as this is an important early step in developing treatments for human disease. However, due to differences between the species, not all treatments that show promise in animal studies go on to be successful in human studies.
Somatostatin also has other inhibitory actions throughout the body, including the brain (where it inhibits thyroid hormones) and the gut (where it supresses several gut and pancreatic hormones, slowing stomach emptying). Reducing the level of this essential hormone will no doubt have widespread consequences and careful analysis of the intended and unintended effects would be needed before any human trials happen.
What did the research involve?
The researcher tested two new somatostatin vaccines, called “JH17” and “JH18”, in male mice with “diet-induced obesity” (in other words, they were fed a high-fat diet). He looked at whether body weight and food consumption changed in the six weeks after vaccination.
The mice used in the study had been fed a diet where 60% of the calories came from fat for the eight weeks before the study and the mice continued on this diet during the study. They had free access to the food at all times. The mice were separated into three groups of ten, and injected on days one and 22 of the study with one of the two vaccines, or an inactive control solution. The mice were weighed twice a week, and their food intake was measured weekly.
What were the basic results?
The researcher found that the vaccinated mice produced antibodies against somatostatin, but the control mice did not. In the two days after the first vaccination, the vaccinated mice showed a reduction in food consumption compared with control mice, and had lost 12%-13% of their body weight by four days after the first vaccination. This large weight loss and concern for the mice’s health led the researcher to reduce the amount of the vaccine given in the second dose at 22 days. After the second dose there was an initial weight loss of about 2% of body weight, but soon the mice began to gain weight again.
While all the mice ate similar amounts of food, the vaccinated mice gained significantly less weight than the control mice. Compared with their body weight at the start of the study, at the end of the six-week study:
- Mice vaccinated with the JH17 vaccine had a 4% increase in their body weight.
- Mice vaccinated with the JH18 vaccine had a 7% increase in their body weight.
- Control mice had a 15% increase in their body weight.
How did the researchers interpret the results?
The researcher concluded that the somatostatin vaccines were “effective in reducing weight gain and reducing final body weight percentage versus baseline weights”. He suggested that further study is warranted in other animal models.
This very early stage research has found some effect of a novel vaccination on weight gain in obese male mice fed a high-fat diet. This research has several limitations.
Issues with the ‘control’ vaccination
The main limitation with this study is that the control injection did not include the same basic solution as the vaccines. Therefore it is unclear whether the effects of the vaccine injections were in fact caused by the solution used for the vaccine, rather than the vaccine itself. However, further experiments using the solution as a control are planned.
Safety of the dose of vaccine given
The results suggested that most of the weight loss occurred shortly after the first vaccination, when mice stopped eating normally. These drastic results prompted the researcher to reduce the dose used for the second vaccination out of concern for the mice’s health. After the initial weight loss, the vaccinated mice gained weight, although they did not catch up with the control mice by the end of the six-week study period.
Overall weight gain
The researcher noted that the effect of the vaccination was short-lived (a food intake reduction for two days after the initial vaccination), which means that repeated doses of the vaccination would be needed to prolong the results.
Unrealistic volume of vaccine required
The researcher noted that the volume of vaccine given to the mice would be the equivalent of giving a 1.6 litre vaccination to a 100kg human – a much greater volume than is used in normal human vaccinations. However, the researcher went on to say that results in pigs suggest that such a large volume may not be needed to produce an immune response.
Overall, these results are not hugely encouraging but have been awarded significant hype in the media. The results in fact illustrate that these vaccinations are not ready for human testing. The idea of a treatment that allows people to continue to eat whatever they like and not gain weight is still fantasy.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.