Tag: food

Is It Folly to Take Folic Acid?

  • Venue: Science Magazine

For mothers-to-be, doctors worldwide advise taking a folic acid supplement. That’s because pregnant women with a deficiency of this vitamin have an increased chance of giving birth to a baby with serious birth defects, such as spina bifida and anencephaly. Yet a new mouse study shows that folic acid supplementation can itself sometimes increase the risk of birth defects or even cause the death of embryos. Experts caution, however, that the unexpected rodent results are too preliminary to require an immediate change in medical practices until more is known about how the vitamin influences development.

People typically obtain folic acid, or folate, from consuming leafy vegetables, but not everyone gets enough from their diet, particularly pregnant women. The vitamin plays a key role in the development of the neural tube, the embryonic region that gives rise to the spinal cord and brain.

Evidence from randomized clinical trials has shown that babies born to women who double their recommended daily dose of folic acid are between 40% and 50% less likely to have birth defects of the spine, skull, and brain. As a result, the United States has fortified most of its grains with this vitamin since 1998, and a handful of other countries have followed suit.

To the surprise of the researchers, in three of the five strains, the extra folic acid seemed to worsen the severity of birth defects rather than remedy them. In one of the mutant lines, dubbed L3P, eating the higher folic acid diet long term increased the chance that young were born with neural tube defects from 20% to 60%, the group reports in the 15 September issue of Human Molecular Genetics. And for another strain, Shroom3, many of whose embryos don’t naturally survive until birth due to their genetic problems, eating the higher folic acid food significantly increased the percentage of lost embryos.

Niswander says it is clear that folic acid is good for human fetuses, but the new study makes her wonder whether high levels of the vitamin may be harmful in some circumstances. Still, she stresses that more data are needed before any serious reconsideration of how much folic acid to recommend for impending mothers.

Roy Pitkin, a retired University of California, Los Angeles, researcher who specialized in pregnant women’s nutrition and chaired an Institute of Medicine panel that in 2000 reviewed folic acid’s health effects also cautions against a rush to judgment: “It would really be throwing the baby out with the bath water to say that because of this one mouse study, we are going to question the food fortification.”

Especially, he says, because we know that species differ considerably from each other when it comes to birth defects. He offers the example of thalidomide—a drug given to pregnant women in the 1950s to cure morning sickness—that causes severe human birth defects but that is perfectly safe in rats.

Neuroscientist Elizabeth Grove of the University of Chicago studies how the mammalian brain develops and echoes this concern. She warns that researchers have found hundreds of mutations that cause birth defects in mice but that so far don’t seem to produce the same problems in humans. The effects of folic acid may also be species specific, she says.

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Lager-brewing yeast identified in Argentina

  • Venue: BBC

Scientists have identified a yeast that led to the discovery of lager.

The researchers isolated the new species in the frozen forests of Patagonia in South America.

Their discovery suggests that this yeast crossed the Atlantic hundreds of years ago and combined with one traditionally used in Europe to make ale.

The discovery is described in the Proceedings of the National Academy of Sciences.

A lucky find

The workhorse of brewing, the yeast Saccharomyces cerevisiae, is used worldwide to ferment fruit and grains to make wine, cider and ale.

Lager, which is fermented more slowly and at lower temperatures than ale, is presumed to be a later invention, and was likely stumbled upon when Bavarian monks moved their beer barrels into caves for storage.

In those caves, Saccharomyces cerevisiae, which prefers to grow just above room temperature, is presumed to have been outcompeted in the fermenting beer by a species that thrived at cooler climes.

The modern-day lager-brewing yeast, Saccharomyces pastorianus, which is a fully domesticated species, is probably a hybrid of this cool-loving strain and the ale-brewing species, and survives because brewers keep back a little of the lager each time to seed the next batch with the same yeast.

Lager’s cradle

“The hybrid almost definitely formed accidentally and people adopted it because the beer came out differently,” said evolutionary biologist Chris Hittinger from the University of Wisconsin in Madison, US, who was one of the team behind the discovery.

But researchers have long wondered where the original cool-loving yeast species came from.

That is until Dr Hittinger and his colleagues isolated it from a beech tree in the forests of Patagonia this year.

These forests, where daily lows average around -2C, are the perfect cradle for modern-day lager-brewing yeast. The species has been designated Saccharomyces eubayanus.

“I personally prefer lagers to ales, and I am very grateful that these two distant cousins met up in a Bavarian cellar hundreds of years ago,” Dr Hittinger told BBC News.

Knowing the ancestral strain to the modern day lager-brewing yeast will help scientists pinpoint the effects of domestication in the genome of brewing yeasts.

And there is also the possibility that there are other undiscovered species of yeast in those Patagonia forests that could become the next best brew.

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Climate to wreak havoc on food supply, predicts report

  • Venue: BBC

Areas where food supplies could be worst hit by climate change have been identified in a report.

Some areas in the tropics face famine because of failing food production, an international research group says.

The Climate Change, Agriculture and Food Security (CCAFS) predicts large parts of South Asia and sub-Saharan Africa will be worst affected.

Its report points out that hundreds of millions of people in these regions are already experiencing a food crisis.

“We are starting to see much more clearly where the effects of climate change on agriculture could intensify hunger and poverty,” said Patti Kristjanson, an agricultural economist with the CCAFS initiative that produced the report.

A leading climatologist told BBC News that agriculturalists had been slow to use global climate models to pinpoint regions most affected by rising temperatures.

This report is the first foray into the field by the CCAFS initiative. To assess how climate change will affect the world’s ability to feed itself, CCAFS set about finding hotspots of climate change and food insecurity.

Focusing their search on the tropics, the researchers identified regions where populations are chronically malnourished and highly dependent on local food supplies.

Then, basing their analysis on the climate data amassed by the United Nations Intergovernmental Panel on Climate Change (IPCC), the team predicted which of these food-insecure regions are likely to experience the greatest shifts in temperature and precipitation over the next 40 years.

Mapping hunger

By overlaying the maps, the team was able to pinpoint which hungry regions of the tropics would suffer most.

With many areas in Africa predicted to become drier, countries such as South Africa which predominately farm maize have the option to shift to more drought resistant crops.

But for countries such as Niger, in western Africa, which already supports itself on very drought resistant crop varieties, like sorghum and millet, there is little room for manoeuvre, explains Bruce Campbell, the director of CCAFS.

“West Africa really stands out as problematic. Burkina Faso, Niger, Mali. They are already dependent on sorghum and millet.

“In many places in Africa you are really going to need [a] revolution in farming systems,” he says.

“We need everything we can lay our hands on,” said Sir Gordon Conway, professor of international development at Imperial College London.

Governments are aiming to limit the average increase in temperature to 2C by the end of the century, he explained. But if temperatures continue to follow their current trajectories “we are on for a 3-4C increase”, Sir Gordon explained.

If this was correct “things get very alarming”, the professor said.

Professor Martin Parry, a visiting professor at the Centre for Environmental Policy at Imperial College London, who co-chaired one of the working groups in the IPCC’s last climate assessment, responded to the report by saying he thought that CGIAR, the parent body to the CCAFS, had been slow to move into the field of climate change as a key area of research. But he added that this step was very welcome.

But he cautioned: “This gives us a better local picture of where the most vulnerable areas might be… but it doesn’t make strong enough connections between the changes in the weather and its impacts on yields.”

This made it difficult to plan for adaptations, Professor Parry told BBC News.

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Monkeys Chew the Cud

  • Venue: Science Magazine

Eating your greens can be grueling, especially if you are a monkey who dines on a high fiber diet. Some primates overcome their digestive dilemma by hosting microbes in their guts that help them breakdown the tougher leaves, much like cows do. Cows and other ruminants also maximize this symbiotic relationship by regurgitating and rechewing their stomach contents to get the most out of each meal. This behavior was considered unique to four-legged herbivores. Now researchers have witnessed proboscis monkeys that live in the mangroves and swamps of Borneo doing the same (see the video). This is the first evidence that primates ruminate, too, reports the team online today in Biology Letters, and gives us all something to chew over.

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Whistling Caterpillars Shake Off Predators

  • Venue: Science Magazine

When in danger, whistle. It works for the walnut sphinx caterpillar (Amorpha juglandis). The fat, juicy larvae of butterflies and moths tend to be experts at predator avoidance, using camouflage, rolling themselves in leaves, and even flicking their own poop to discourage birds, frogs, and small mammals from eating them. Whistling is just another string in their bow, researchers report online this week in The Journal of Experimental Biology. When the team used forceps to simulate the peck of a bird’s beak, the caterpillars forced air through the small holes on either side of their body—normally used for breathing—to produce a high-pitched whistle. When yellow warblers heard the noise, these natural enemies of the caterpillars hesitated, jumped back, or flew off. The sound may have startled them, or perhaps they found the tune indigestible.

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How to Feed a 180-Ton Whale

  • Venue: Science Magazine

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For the blue whale, feeding is an Olympic event. The largest animal on Earth dives 500 meters at speeds of up to 3 meters per second, U-turns toward the surface, and then opens its colossal mouth to scoop up clouds of krill and filter them from the water with its brushlike teeth. A new study reveals that this massive energy expenditure is worth it. Although the whales are feasting on some of the smallest creatures on the planet, the dive fills them with enough sustenance to survive.

To understand the energetics of the blue whale’s feeding behavior, Robert Shadwick, a biomechanic at the University of British Columbia in Canada, and colleagues analyzed data collected from digital tags suctioned-cupped to the whales’ back. The tags, which travel with the animal on its descent to the clouds of shrimplike krill, measure the animal’s speed, depth, orientation and the number of times it beats its tail; they then pop off and float to the surface, ready to be retrieved by pursuing biologists. Combining data from these tags with measurements of whale jaws from museum specimens, the team modeled the drag experienced by the whale as it performs its complex underwater acrobatics.

The whales use about 63,000 kilojoules of energy on each dive, the researchers report online today in The Journal of Experimental Biology. But they also eat about 1260 kilograms of krill, as calculated from the average number of krill present in the 80 metric tons of water they gulp. And that provides the whales with about 100 times more energy from the tiny creatures than they spend capturing them.

Blue whales need that extra energy because they devote such a small proportion of their lives to feeding, says Ann Pabst, a functional morphologist at the University of North Carolina, Wilmington, who was not involved with the study. She notes that the animals spend many months either migrating to and from feeding grounds or reproducing, and during these periods they must survive off their fat reserves.

Pabst adds that the new study was possible only because of new tagging technologies, which were developed by the U.S. Navy to measure pressure deep in the ocean. The tags provide so much information that “we can almost visualize what is going on at [these] depths,” she says.

The researchers hope the work aids conservation efforts. Due in part to increased human consumption of krill as fish stocks run low, blue whale numbers are only 3% of what they were in the 1800s. The data could help conservationists make a stronger argument for how much krill the whales need to survive.

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Sharks Chew Off More Than They Can Bite

  • Venue: Science Magazine

Teenage great white sharks might look all grown up, but they don’t have the awesome bite of a fully grown adult, researchers report online today in the Journal of Biomechanics. The team built a computer model based on measurements taken of the head of a young great white shark and its cousin, the sand tiger shark (seen here chomping down on a bait fish). Based on the structure of the sharks’ cartilage and muscle, the model indicates that the jaws of young great whites haven’t fully stiffened. This means that, although their gape is wide enough, the sharks can’t feast on the flesh of seals and other large mammals without damaging their jaws. The researchers hope the work helps conservation biologists better understand the sharks’ feeding behavior and protect their prey species.

See the movie of the biting shark.

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Odor Exposure in the Womb Primes the Palate

  • Venue: Science Magazine

Moms, want your children to eat their greens? Then you have to eat them, too, at least while you’re pregnant. Researchers have found that offspring of mouse mothers fed a diet enhanced with cherry and mint flavors during pregnancy continued to prefer these flavors into adulthood, while mice from mothers fed on a bland diet had no food preference. The rodents with a penchant for mint-cherry food developed larger glomeruli, the region of the brain responsible for processing odor—the first evidence that exposure to odors in the womb alters the way the brain develops. From the fetus’ point of view, this is a good evolutionary strategy; eat the foods that your mother ate because they are probably safe. It is likely that all mammals, including humans, develop their sense of taste in this same way, the researchers report online today in the Proceedings of the Royal Society B, so expectant moms, be careful the next time you have a hankering for anchovies with chocolate sauce.

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Fish Sleep Soundly in Mucous Cocoons

  • Venue: Science Magazine

Even the ocean has bedbugs. Tiny blood-sucking crustaceans (inset) roam the seas, nipping at the scales of passing fish. But the parrotfish (Chlorurus sordidus) has evolved an unusual defense. According to a study published online today in the Proceedings of the Royal Society B, the fish spend up to an hour spinning cocoons from their own mucous before they settle down to slumber for the night. These transparent, gelatinous balls of spit are large enough to envelope the fish from head to tail. By gently pushing fish from their cocoons without waking them, researchers showed that those sleeping without protection were 80% more likely to be bitten by the crustaceans than those they left untouched. Producing these mucous membranes costs just over 2% of the fish’s daily energy budget; apparently a worthwhile investment against things that go bite in the night.

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