Food makes the difference

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 in Madison gave a group of rhesus macaques (macaca mulatta) 30% fewer calories than a control group. According to the results from Wisconsin, calorie restriction allows monkeys to live longer and healthier; 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 discrepancies observed might be due to the special conditions of the food given to the animals, even though the calorie restriction levels were similar. “Diet is a 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 account 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, a nutritionist for aquatic organisms at the University of Alabama in Birmingham. “As long as the animals looked happy and healthy, the researchers were satisfied.” he sums up.

Standardized pills

The tide began to turn in 1977, when a report from the American Institute for Nutrition in Rockville, Maryland offered guidelines for eliminating dietary confusion in medical research. Since then, scientists have developed several standardized diets for farms and laboratories; a number of standardized pellets have been produced for laboratory rats and mice. “We realized that nutrition was a key element in improving the rigor and reproducibility of experiments”notes Stephen Watts.

However, these standardized diets still have many variations and are not available to many commonly used animals. When they were developed, the goal was often to limit their cost and maximize their practical function rather than to mimic the animals’ habits in the wild.

Therefore, it is 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 in Bloomington who works with the divergences of r.

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Source of the article

Nature (London)

Since 1869, this well-deserved scientific journal has received – after months of scrutiny – reports on major innovations in all areas: 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 that are available to the public.

Like other newspapers, Nature offers archives dating back to 1987. But their aggregation with all the more specialized publications from its press group, Nature Publishing Group, gives the visitor access to a very large amount of information. The very simple classification by scientific fields – chemistry, pharmacy, oncology, biotechnology, immunology – greatly facilitates research. Another very practical point, all articles are dotted with numbered bibliographic notes, which refer directly to another online article. The paper version suggests a summary of the articles available online.

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