Category: Nutrition (page 7 of 7)

how camels survive in the desert

An Arabian Camel

Genomic studies are helping researchers determine what is unique about these dessert dwelling mammals. It turns out it is mostly their metabolism. From Scientific American:

Camels, as ruminants like cattle and sheep, digest food by chewing the cud. But many of the Bactrian genome’s rapidly evolving genes regulate the metabolic pathway, suggesting that what camels do with the nutrients after digestion is a whole different ball game. “It was surprising to me that they had significant difference in the metabolism,” says Kim Worley, a molecular geneticist at Baylor College of Medicine in Houston, Texas. The differences could point to how Bactrians produce and store energy in the desert.

The work shows that camels can withstand massive blood glucose levels owing in part to changes in genes that are linked to type II diabetes in humans. The Bactrians’ rapidly evolving genes include some that regulate insulin signaling pathways, the authors explain. A closer study of how camels respond to insulin may help to unravel how insulin regulation and diabetes work in humans. “I’m very interested in the glucose story,” says Brian Dalrymple, a computational biologist at the Queensland Bioscience Precinct in Brisbane, Australia.

The researchers also identified sections of the genome that could begin to explain why Bactrian camels are much better than humans at tolerating high levels of salt in their bloodstreams. In humans, the gene CYP2J controls hypertension: suppressing it leads to high blood pressure. However, camels have multiple copies of the gene, which could keep their blood pressure low even when they consume a lot of salt, suggest the authors of the latest work.

The study appears in Nature Communications.

how much meat did cavemen eat?

It turns out that cavemen might not have chomped away on gigantic bison burgers as we often think.  It had been estimated that protein intake made up 60-80 percent of the caveman’s diet.  A new study suggests that this is wrong as only about 45 percent of the modern diet consists of protein. And that is protein of any type, not just from meat.  From Scientific American:

 [M]any studies estimate that between 60 and 80 percent of the prehistoric human diet came from proteins, with most of that from animal sources.

That was surprising because no more than 45 percent of modern diets come from protein of any type.

That contradiction led O’Connell to wonder if the offset was wrong because it relied on animal estimates, not humans.

To find out, her team took human blood samples from a study where scientists meticulously re-created people’s usual diets, measured exactly how much they ate over a week, and took precise samples of each meal. By comparing the nitrogen isotope ratios in the food and human blood samples, they were able to estimate how much heavy nitrogen the human body stores. (They then extrapolated their estimate for blood samples to human hair and to bone.)

Previous estimates based on animal studies were too small and thus inflated how much animal protein our ancient ancestors ate, she said.

Instea
“We are suggesting that animal proteins would be less important overall and that’s particularly true for interpretations of Neolithic farmers,” she said. “What that would mean is that they are having more of a balance of animal and plant proteins in their diet, suggestive of a mixed existence strategy.”d, the first farmers, who lived around 12,000 years ago, likely ate no more than 40  to 50 percent of their protein from animal sources. Those people ate a diet more similar to subsistence farmers in modern-day India or China, O’Connell said. Hunter-gatherers from the Paleolithic period also ate less meat, she added.

today’s no duh headline

“Fruit and Veggies Linked to Lower Obesity Rates…” Isn’t this nutrition 101? Read the story at NPR’s the salt blog.

//ourtoonoolr.net/4/4535925