Nutrition – Page 3

07.18.2014

truvia is toxic to fruit flies

Dead fruit fly. Picture from wikipedia

C&EN describes how a sixth grade science project lead to the discovery that Truvia, a sweetner from the stevia plant, is toxic to fruit flies:

The discovery wouldn’t have been possible without Simon D. Kaschock-Marenda, who went to his dad three years ago to pitch an idea. Knowing that his father was a neurobiologist at Drexel with access to a supply of fruit flies, the sixth-grader proposed a science fair project: He wanted to feed a variety of sugars and sweeteners to flies and see how the insects fared.

One of the sweeteners father and son purchased from the supermarket for testing was Truvia, made by Minneapolis-basedCargill. The pair mixed that sweetener and a number of others with Drosophila food, put each in a container with adult fruit flies, and waited.

Almost a week later, Marenda’s son pointed out that the flies in the Truvia container had died, while the ones feeding off the other sweeteners were still alive. Thinking the result might be a fluke, the youngster and his father repeated the experiment, only to obtain the same result. Flies raised on the Truvia-laced food survived for about six days, and flies fed table sugar lived around 40 to 50 days.

The research was moved into the father’s lab where he discovered that erythritol is responsible for toxicity:

[F]ruit flies given food laced with Pure Via, another sweetener derived from the stevia plant, didn’t react as they had to Truvia. Their life span was unaltered.

So O’Donnell sent Truvia off to be analyzed with high-performance liquid chromatography and got interesting results. “More than 90% of the Truvia was erythritol,” Marenda says.

[…]

To determine whether erythritol was indeed their culprit, Marenda, O’Donnell, and their team placed fruit flies in containers with increasing doses of erythritol. At the highest concentration the researchers tested—2 M erythritol—all the flies died after a day or two of feeding.

07.03.2014

the science of drunk food

Over at Science of Us, Julia Reinstein at tries to explain why we crave junk food after imbibing:

Plenty of sober people crave junk food, of course, but booze ratchets up these cravings by messing with your blood-sugar levels. When your liver is all tied up processing excessive alcohol levels, it can interfere with normal blood-sugar production, resulting in a dip in your blood-sugar level (kind of ironic, considering how sugar-packed your cranberry-vodka is) that causes you to crave foods that will bring it back up. Doing so with an apple rather than buffalo wings is challenging under the best of circumstances, but when your inhibitions are lowered, you’re even more likely to choose whatever’s quick and satisfying in that moment.

Researchers at Northwestern University demonstrated this in one particularly deliciousexperiment. They left two groups of subjects, one drunk and one sober, with unlimited ice cream and told them they could eat as much as they wanted. The drunk group ate a lot more of the ice cream, and this held true even when the subjects ingested the alcohol unknowingly (quite an experiment …), suggesting it wasn’t simply about social or cultural norms pertaining to alcohol and food. Rather, the researchers argued, alcohol simply makes people more relaxed, and when people are relaxed, they’re more likely to indulge. The blood-sugar thing and the lowered-inhibitions thing, then, are a potent one-two punch straight to the face of healthy eating.

07.01.2014

getting rid of e. coli

A tube of human serum albumin and poly-arginine can be made just the right size to filter harmful E. coli from drinking water

E. coli bacteria are common and most are not harmful to humans. Some strains, however, can pose severe threats to human health. Every once in a while you hear of food recalls due to harmful strains of E. coli contaminating food or drinking supplies. This is especially a problem in developing nations, where food may be washed in contaminated water and cause food poisoning.

A group of Japanese researchers have developed a way to remove E. coli bacteria from water supplies using tubes made from human serum albumin and poly-arginine peptides. Scientific American describes the process:

The elegant method, devised by Teruyuki Komatsu and co-workers at Chuo University, Tokyo, begins by depositing microtubes made from alternating layers of human serum albumin (HSA) and poly-L-arginine onto a polycarbonate template. The template is then dissolved away to leave a hollow tube, which is just the right size to fit the E. coli bacterium. Key to removing E. coli from a solution is its strong binding affinity for HSA, which attracts the bacteria into the tube. So effective is this binding, that just 1.5μg of microtubes, added to a liter of contaminated water containing 100,000 bacteria were able to remove the bacteria with almost 100% efficiency. The final touch is the incorporation of a layer of magnetite (iron (II) oxide) nanoparticles into the microtubes to allow their easy removal from the solution using a magnetic field.

GOLLYGEE!

Category: Nutrition (page 3 of 7)

truvia is toxic to fruit flies

the science of drunk food

getting rid of e. coli