In the 1980s, in the United States, two teams of researchers asked themselves a seemingly simple question: can animals live longer if they eat less? A team from the National Institutes of Health (NIH) in Bethesda, Maryland, and one from the University of Wisconsin at Madison gave a group of rhesus macaques (Macaque mulatto) 30% fewer calories than a control group. According to the results from Wisconsin, calorie restriction allows monkeys to live longer and healthier lives; but according to those at the NIH, it has no such effect.
To understand the reason for this difference, the researchers looked at the conditions of the two experiments. Thus they realized that the observed discrepancies were perhaps due to the particularities of the food provided to the animals, even though the caloric restriction levels were similar. “Diet is one variable among others”, explains Kristin Gribble, a molecular biologist at the Marine Biological Laboratory in Woods Hole, Massachusetts.
“If it is not identical in two experiments, it constitutes an additional variable to be taken into consideration in the analysis of the results.”
In the past, researchers often overlooked the importance of animal nutrition when designing their experiments, points out Stephen Watts, an aquatic organism nutrition specialist at the University of Alabama at Birmingham. “As long as the animals looked happy and healthy, the researchers were satisfied,” he summarizes.
Standardized pellets
The tide began to turn in 1977, when a report from the American Institute for Nutrition in Rockville, Maryland offered guidelines for eliminating dietary confounders in medical research. Since then, scientists have developed multiple standardized diets for farms and laboratories; a variety of standardized pellets have been produced for laboratory rats and mice. “We realized that nutrition was a key element to improve the rigor and reproducibility of experiments”note Stephen Watts.
However, these standardized diets still have many variations and are not available for many commonly used animals. When they were developed, the aim was often to limit their cost and maximize their practicality, rather than to imitate the habits of animals in nature.
It is therefore crucial to carefully document the experimental conditions to improve the replicability of the experiments, points out David Allison, a biostatistician at the University of Indiana at Bloomington who works on the divergences of r
The rest is reserved for subscribers…
- Access all subscribed content
- Support independent writing
- Receive the Mail Alarm Clock every morning
Source of the article
Nature (London)Since 1869, this well-deserved scientific journal has received – after several months of checks – reports on major innovations in all fields: from biology to physics and including astronomy. His age does not prevent him from remaining surprisingly dynamic. In addition to articles intended for researchers and scientists, the journal also offers pages of news, debates and files accessible to the general public.
Like other newspapers, Nature offers archives dating back to 1987. But their pooling with all the more specialized publications of its press group, Nature Publishing Group, allows the visitor to access a very substantial mass of information. The very simple classification by scientific fields – chemistry, pharmacy, oncology, biotechnology, immunology – greatly facilitates research. Another very practical point, all the articles are dotted with numbered bibliographical notes, which refer directly to another online article. In the paper version, a summary of the articles accessible on the Net is proposed.
Read more
Nos services