Nutrition researchers urge update to lab animal diets | Science

Reformulating the usual mouse weight loss plan might make animals more healthy and experiments extra dependable.

Pascal Goetgheluck/Science Source

The pile of beige meals pellets in a lab mouse’s cage won’t be probably the most thrilling a part of an experiment, however it’s a element researchers can’t afford to disregard. Nutrition scientists met final week to debate attainable revisions to the just about 30-year-old formulation of the weight loss plan consumed by laboratory rats and mice—probably the most generally used animals in biomedical analysis. At a session of the online American Society for Nutrition (ASN) meeting, researchers described how making rodent feed extra nutritious and constant would enhance the animals’ well being and restrict attainable confounding variables in experiments.

“Having animals at their healthiest after which modifying the weight loss plan” provides researchers “a greater base” to discover the results of particular vitamins—and to grasp how and when animals develop ailments, says Michael Pellizzon, a senior diet scientist on the lab animal weight loss plan producer Research Diets, Inc., and a panelist on the ASN session.

Last yr, Pellizzon co-authored a paper describing ways in which diet choice can influence the results of experiments. For instance, grain-based rodent diets usually comprise unspecified quantities of a category of hormonelike compounds known as phytoestrogens. These can have an effect on the onset of puberty in rodents and their threat of creating most cancers, probably obscuring the impacts of a drug, toxin, or nutrient being studied.

Prior to the Sixties, there was no customary formulation for rodent meals, and researchers had little details about their vitamin and mineral content material. In the Seventies, a committee of the American Institute of Nutrition developed AIN-76A, the primary broadly accepted, publicly accessible weight loss plan components for rats and mice. It described pellets comprised largely of sugar and milk protein, enriched with particular concentrations of nutritional vitamins, minerals, and amino acids to fulfill all of the rodent dietary necessities identified on the time. Since the early Nineties, researchers have used a barely modified components known as AIN-93.

But researchers have recognized shortcomings with the components. Purified, nonnatural diets comparable to AIN-93, which comprise refined, easy-to-digest substances, can result in numerous abnormalities in lab mice that might have an effect on experimental outcomes, together with a buildup of fats, a lack of regular intestinal micro organism, and a discount within the dimension of the intestines.

“It’s virtually 30 years later and AIN-93 hasn’t been revised. And in fact, right now we all know much more about diet now and the way vitamins work,” says Marta Fiorotto, a diet scientist at Baylor College of Medicine and a panelist on the ASN session. “There have been lots of [people] within the diet neighborhood saying, ‘Well sure, we see why we use this weight loss plan, however it’s acquired issues.’”

Fiorotto doesn’t assume the rodent weight loss plan wants a whole overhaul. She and different panelists urged diet researchers to share “well-documented, scientifically right” observations about how their animals’ weight loss plan influenced their examine outcomes. Several assembly attendees agreed that AIN-93 was due for an improve, and a few instructed potential enhancements, comparable to modifying the quantity of fiber, chromium, calcium, and protein within the pellet.

But updating rodent diets might be an uphill battle. The prospect of reformulation has been studied and mentioned earlier than, Fiorotto says, however “typically it’s very troublesome to get a bunch of individuals collectively to agree on one thing.” If diet scientists can attain a consensus that reformulation is critical, she says, the following step is to compile accessible analysis on the difficulty and establish a gaggle of consultants to make suggestions that feed producers might observe.

There’s one other problem: Even although these producers already provide fastidiously standardized rodent diets, many researchers nonetheless depend on inexpensive options constructed from nonpurified pure substances, comparable to floor corn, dried beef, pork, and fish. The quantities of particular substances on this chow are not often disclosed and may change from batch to batch, which makes it onerous to regulate particular person nutrient ranges in an experiment. It could be very troublesome for a researcher to conduct—or replicate—a examine on how totally different ranges of copper impacts the well being of lab rodents, for instance, as a result of this important nutrient can seem in chow at various concentrations with out being labeled.

Some scientists go for this much less clear weight loss plan as an alternative of the standardized one as a result of they doubt a cautious formulation issues a lot for the questions they’re learning, Fiorotto says. But, “In order to do good diet analysis with mice and rats,” she says, “it’s essential to make use of diets the place you understand precisely what’s in them.”

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