For years, scientists have thought cooked foods are easier to digest, and thus, are more nutritious than non-cooked eats.
Before now, though, they lacked the evidence needed to confirm these claims for meat. But a recent experiment suggests that cooked meat packs more nutritional value than its raw counterpart. The findings could give clues to how early humans gained more energy from cooking meats as well as provide insight on ways to maximize nutrition today.
The researchers tested foods in the ways that they're actually digested in organisms, rather than analyzed outside of the body.
The experiment involved feeding groups of mice variations of organic beef or sweet potatoes over a 40-day period. Different diets included raw/intact, raw/pounded, cooked/intact and cooked/pounded foods (either the beef or the sweet potato). Mice could eat food freely, and researchers monitored the rodents' activity levels and body mass.
While activity didn't differ across groups, body mass did. All mice lost weight on the diets, but those consuming cooked foods lost less than others eating raw foods. This means that the mice were getting more energy from the cooked foods, especially the meat.
The paper's authors think a few mechanisms might be at play. First, cooking seems to unwind proteins in meat, which could make it easier to digest in the small intestine before gut bacteria take their share of the pie. In addition, cooking meat seems to loosen muscle fiber connections, making the foods easier to chew.
The way foods are prepared — whether they're pounded, crushed, sliced, and so on — also matters. Pounded foods appeared to provide more energy, but not as much as cooking. Yet while pounding breaks down the structure of food fibers, it doesn't have as much of an effect on cells at the molecular level. This is where cooking has the advantage. Incorporating both cooking and pounding produced the best results.
Anthropologists think early humans began using fire to cook foods some 1.8 million years ago. Though the archaeological evidence is sparse, some scientists adopt this time frame and support that cooking may have lifted the energetic constraints that allowed humans to develop larger brains.
Cooking meats may have allowed people to preserve food longer as well as save the immune system the trouble of fighting off certain foodborne pathogens that are killed by the cooking process.
Still, more research is needed to find out what's at the root of these findings. Also, the small study relies on the underlying assumption that mice and humans have similar digestive systems (which they do, for the most part). Mice and humans share omnivorous diets, but have different teeth and overall energy budgets. It's unclear whether other factors make mice's meat consumption that much different from humans'.
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