How a giant impact formed asteroid Vesta's 'belt'

 

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A massive collision: A high-speed camera recorded a laboratory simulation of colliding heavenly bodies. An analysis of shock propagation suggests what may have caused the tilted canyon-like grooves around the equator of the asteroid Vesta.

Collisions of heavenly bodies generate almost unimaginable levels of energy. Researchers at Brown used NASA's ultra-high-speed cannon and computer models to simulate such a collision on Vesta, the second-largest object in the asteroid belt. Their analysis of the images -- taken at a million frames per second -- shows how Vesta may have gotten the deep grooves that encircle its midsection.

When NASA's Dawn spacecraft visited the asteroid Vesta in 2011, it showed that deep grooves that circle the asteroid's equator like a cosmic belt were probably caused by a massive impact on Vesta's south pole. Now, using a super high-speed cannon at NASA's Ames Research Center, Brown University researchers have shed new light on the violent chain of events deep in Vesta's interior that formed those surface grooves, some of which are wider than the Grand Canyon.

"Vesta got hammered," said Peter Schultz, professor of earth, environmental, and planetary sciences at Brown and the paper's senior author. "The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior."

The research suggests that the Rheasilvia basin on Vesta's south pole was created by an impactor that came in at an angle, rather than straight on. But that glancing blow still did an almost unimaginable amount of damage. The study shows that just seconds after the collision, rocks deep inside the asteroid began to crack and crumble under the stress. Within two minutes major faults reached near the surface, forming deep the canyons seen today near Vesta's equator, far from the impact point.

The research, led by Angela Stickle, a former graduate student at Brown and now a researcher at the Johns Hopkins University Applied Physics Laboratory, will appear in the February issue of the journal Icarus and is now available online.

"As soon as Pete and I saw the images coming down from the Dawn mission at Vesta, we were really excited," Stickle said. "The large fractures looked just like things we saw in our experiments. So we decided to look into them in more detail, and run the models, and we found really interesting relationships."

For the study, the researchers used the Ames Vertical Gun Range, a cannon with a 14-foot barrel used to simulate collisions on celestial bodies. The gun uses gunpowder and compressed hydrogen gas to launch projectiles at blinding speed, up to 16,000 miles per hour. For this latest research, Schultz and his colleagues launched small projectiles at softball-sized spheres made of an acrylic material called PMMA. When struck, the normally clear material turns opaque at points of high stress. By watching the impact with high-speed cameras that take a million shots per second, the researchers can see how these stresses propagate through the material.

The experiments showed that that damage from the impact starts where one would expect: at the impact point. But shortly after, failure patterns begin to form inside the sphere, opposite the point of impact. Those failures grow inward toward the sphere's center and then propagate outward toward the edges of the sphere like a blooming flower.

Using numerical models to scale the lab collision up to the size of Vesta, the second-largest object in the asteroid belt, the researchers showed that the outward-blooming "rosette" of damage extending to the surface is responsible for the troughs that form a belt around Vesta's equator.

The results answer some questions about Vesta's belt that had long been puzzling. Chief among them is the orientation of the belt with respect to the crater. The belt's angle isn't exactly what would be expected if it were caused by the Rheasilvia impact.

"The belt is askew," Schultz said, "as if Vesta were making a fashion statement."

These new experiments suggest that the crooked belt is the result of the angle of impact. An oblique impact causes the damage plane to be tilted with respect the crater. The orientation of Vesta's belt sheds light on the nature of the impact. The researchers conclude that the object that created Rheasilvia came in at an angle less than 40 degrees, traveling at about 11,000 miles per hour.

"Vesta was lucky," Schultz said. "If this collision had been straight on, there would have been one less large asteroid and only a family of fragments left behind."

The research shows that even a glancing blow can have tremendous consequences.

"When big things happen to small bodies," Schultz said, "it shakes them to the core."

Astronomers solve puzzle about bizarre object at center of our galaxy: Enormous black hole drove two binary stars to merge

 

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Telescopes from Hawaii's W.M. Keck Observatory use a powerful technology called adaptive optics, which enabled UCLA astronomers to discover that G2 is a pair of binary stars that merged together, cloaked in gas and dust.

For years, astronomers have been puzzled by a bizarre object in the center of the Milky Way that was believed to be a hydrogen gas cloud headed toward our galaxy's enormous black hole.

Having studied it during its closest approach to the black hole this summer, UCLA astronomers believe that they have solved the riddle of the object widely known as G2.

A team led by Andrea Ghez, professor of physics and astronomy in the UCLA College, determined that G2 is most likely a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust -- its movements choreographed by the black hole's powerful gravitational field. The research is published today in the journal Astrophysical Journal Letters.

Astronomers had figured that if G2 had been a hydrogen cloud, it could have been torn apart by the black hole, and that the resulting celestial fireworks would have dramatically changed the state of the black hole.

"G2 survived and continued happily on its orbit; a simple gas cloud would not have done that," said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. "G2 was basically unaffected by the black hole. There were no fireworks."

Black holes, which form out of the collapse of matter, have such high density that nothing can escape their gravitational pull -- not even light. They cannot be seen directly, but their influence on nearby stars is visible and provides a signature, said Ghez, a 2008 MacArthur Fellow.

Ghez, who studies thousands of stars in the neighborhood of the supermassive black hole, said G2 appears to be just one of an emerging class of stars near the black hole that are created because the black hole's powerful gravity drives binary stars to merge into one. She also noted that, in our galaxy, massive stars primarily come in pairs. She says the star suffered an abrasion to its outer layer but otherwise will be fine.

Ghez and her colleagues -- who include lead author Gunther Witzel, a UCLA postdoctoral scholar, and Mark Morris and Eric Becklin, both UCLA professors of physics and astronomy -- conducted the research at Hawaii's W.M. Keck Observatory, which houses the world's two largest optical and infrared telescopes.

When two stars near the black hole merge into one, the star expands for more than 1 million years before it settles back down, said Ghez, who directs the UCLA Galactic Center Group. "This may be happening more than we thought. The stars at the center of the galaxy are massive and mostly binaries. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now."

Ghez and her colleagues also determined that G2 appears to be in that inflated stage now. The body has fascinated many astronomers in recent years, particularly during the year leading up to its approach to the black hole. "It was one of the most watched events in astronomy in my career," Ghez said.

Ghez said G2 now is undergoing what she calls a "spaghetti-fication" -- a common phenomenon near black holes in which large objects become elongated. At the same time, the gas at G2's surface is being heated by stars around it, creating an enormous cloud of gas and dust that has shrouded most of the massive star.

Witzel said the researchers wouldn't have been able to arrive at their conclusions without the Keck's advanced technology. "It is a result that in its precision was possible only with these incredible tools, the Keck Observatory's 10-meter telescopes," Witzel said.

The telescopes use adaptive optics, a powerful technology pioneered in part by Ghez that corrects the distorting effects of the Earth's atmosphere in real time to more clearly reveal the space around the supermassive black hole. The technique has helped Ghez and her colleagues elucidate many previously unexplained facets of the environments surrounding supermassive black holes.

"We are seeing phenomena about black holes that you can't watch anywhere else in the universe," Ghez added. "We are starting to understand the physics of black holes in a way that has never been possible before."

Lemurs: Gardeners of Madagascar rainforest at risk

 

A large proportion of trees in Madagascar's rainforest have fruits eaten by lemurs. Lemurs in turn disperse the seeds of their fruit trees throughout the forest with their scat. Such dispersal can play a crucial role for a tree species' ability to regenerate, but effects are poorly understood, especially when there are multiple dispersers.

For the tree, the evolutionary advantage of having animal-dispersed seeds may be that the seeds land well away from their parent trees where survival is low or that seeds are directed into spots where they are the most likely to sprout and survive.

Amy Dunham, an assistant professor of biosciences, and graduate student Onja Razafindratsima set out to detail the symbiotic relationship between fruit-eating lemurs and the trees that feed them through a three-year study in a rainforest in southeastern Madagascar.

Their data from observations, experiments and mathematical models demonstrate that seeds of a common canopy tree have a 300 percent higher chance of sprouting and becoming a sapling when dispersed by lemurs versus simply falling to the ground. One of the three lemur species is particularly good at dropping seeds in spots that are most advantageous for sprouting and survival. Other lemurs are not so selective, but still benefit the tree by moving seeds away from the parent tree. By acting as forest gardeners, these animals give the tree's population a boost.

The study appeared online in the Ecological Society of America journal Ecology.

As part of the study, the researchers followed the seed-dispersal patterns of three of Madagascar's lemur species: the red-fronted brown lemur, the red-bellied lemur and the southern black-and-white ruffed lemur. That meant tracking and observing groups of lemurs as the animals leaped from tree to tree through the forest, dined in the 65-foot-high canopies and dropped their undigested seeds at ground level.

Razafindratsima led the study as part of a thesis project she expects to complete early next year. She built a team of local researchers near Ranomafana National Park, the home of Centre ValBio, a research station founded by Dunham's former Ph.D. adviser, primatologist Patricia Wright.

"We have a team of up to 10 local villagers who are trained to do research," said Razafindratsima, a native of Madagascar. "Their exceptional knowledge of the forest is very important to us when we're trying to track lemurs and identify seeds and seedlings in a forest with over 300 species of trees."

The research team tracked 24 groups of lemurs over a year without the benefit of radio collars, said Razafindratsima, who keeps in touch with her team via phone and Skype when she's at Rice. She said the study sites were as close as a short hike from Centre ValBio and as far as a two-day trek through steep terrain that entailed camping overnight.

In addition to tracking lemurs and their dispersed seeds, the research team spent three years carrying out experiments on seed sprouting and survival. They found that dispersal by lemurs dramatically increased the odds that seeds would take root and survive. In particular, the red-fronted brown lemurs tended to drop seeds away from their parent trees and in places where there were gaps in the canopy. This gave individual seeds the best shot at taking root.

Dunham said trees benefit from the wide dispersal of their seeds, and for some species in Madagascar, lemurs are the primary or only animal that can distribute those seeds. As the largest fruit-eaters in the system, these lemurs swallow seeds that may be too large for other fruit-eating animals, such as birds or bats.

"Seeds away from the parent tree survive better because there's less competition among seedlings," Razafindratsima said. "If they're close by the parent, they may also share the same natural enemies, like soil pathogens and seed predators, so there's higher mortality."

Trees that lose their dispersers will simply drop their seeds to the ground beneath their canopies, where chances of survival are slim, Dunham said. "Lemurs fill an important role as the gardeners for these trees. By ensuring that some seeds land in spots suitable for germination and survival, they increase the ability of these trees to replace themselves"

Dunham hopes the study will contribute to growing efforts to protect lemurs, and therefore the rainforest, which has been impacted in recent years by economic and political instability. She noted grassroots efforts within Madagascar led to the first World Lemur Festival in late October to celebrate and protect the animals and their habitats in Madagascar.

"What got us interested is that frugivorous lemur populations are declining across the island, and we know very little about how these seed dispersers actually affect tree populations," she said. "Once we understand that better, maybe we'll have a better idea of how the community might change if the lemurs disappear.

"If some species suddenly lose their dispersers, but others dispersed by birds or the wind are doing fine, it may change population trajectories and alter which tree species are dominant in a community. To understand what happens when these species are lost, we need to understand their role in the ecosystem," she said.

Putting batteries in a kidsafe coat of armor

 

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A Brigham and Women's Hospital (BWH) led team has developed a simple "coat of armor" to encase small batteries, rendering them harmless if they are ever swallowed. Children, particularly infants and young toddlers, can ingest these batteries, leading to serious damage to their esophagus as well as other gut tissue, and sometimes, death. Such incidents are on the rise, yet up until now, no solutions have been directed at the battery itself. The new work, published online November 3, 2014 in the Proceedings of the National Academy of Sciences, offers a simple, cost-effective fix that if implemented, could dramatically reduce if not eliminate, this unfortunate problem.

"To date, there has been no innovation to address this issue with small batteries," says Jeff Karp, PhD, BWH Division of Biomedical Engineering in the Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute. "To address this challenge we sought to develop something that would render the battery inert, specifically when it was outside of a device."

Each year, roughly 5 billion "button" batteries are produced across the world. These small, disc-shaped batteries power everything from children's toys, hearing aids and laser pointers to remote controls and musical greeting cards. While recent legislation requires battery compartments in children's toys to be secured with screws, many items commonly used by adults contain these batteries in easily accessible formats and their packaging provides no protection. With the proliferation of such gadgets, and the demand for ever-powerful batteries to power them, the problem of accidental ingestion is increasing. In 2013, there were more than 3,000 reported cases of accidental battery ingestion -- the majority in children under age 6.

"Ingested disc batteries require emergent removal from the esophagus," says co-first study author Giovanni Traverso, MB, BCh, PhD, a gastroenterologist at Massachusetts General Hospital and a researcher at MIT. "The swallowing of these batteries is a gastrointestinal emergency given that tissue damage starts as soon as the battery is in contact with the tissue, generating an electric current and leading to a chemical burn."

Karp and his colleagues became aware of this issue in 2010, and decided to apply their collective expertise toward developing a novel solution. "This seemed like a tractable problem that we could make significant headway on in a short period of time, just based on our expertise in materials and devices," says Karp.

Karp, together with first author Bryan Laulicht, PhD, a postdoctoral fellow in Karp's lab, noticed that when a battery sits within a device, there is gentle pressure applied to it, yet when it is outside the device, such force does not exist.

"We set out to create a specialized coating that could switch from an insulator to a conductor when subjected to pressure," said Co-author Robert Langer, Institute Professor from the Harvard-MIT Division of Health Sciences and Technology.

The scientists discovered this unique substance in an unlikely place -- touch screens. Using an off-the-shelf material known as a quantum tunneling composite, they identified a nanoparticle-based coating that, when subjected to pressure, allows an electrical current to pass through. In contrast, it allows no current to run in the absence of such pressure.

They used this material to coat one side of the batteries -- covering the "minus" ends or the anodes. To determine the coating's effectiveness, they teamed up with Traverso, exposing coated and uncoated batteries to gut tissue both in a laboratory dish and in living animals. In all cases, the coated batteries caused no damage while the uncoated batteries, as expected, caused significant damage.

In addition to reducing injuries, this innovation is also likely to be quite cost-effective. "The ultimate cost will depend on the exact composition of the material that is used, but for our current formulation, we're talking cents, not dollars," says Laulicht, first author of the paper.

Now, Karp and his colleagues are working to determine the best route toward manufacturing and scaling up to a sufficiently large number of batteries, and then working with battery manufacturers to get the coated batteries into the hands of consumers.

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Story Source:

The above story is based on materials provided by Brigham and Women's Hospital. Note: Materials may be edited for content and length.

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Journal Reference:

1. Bryan Laulicht, Giovanni Traverso, Vikram Deshpande, Robert Langer, and Jeffrey M. Karp. Simple battery armor to protect against gastrointestinal injury from accidental ingestion. PNAS, 2014 DOI: 10.1073/pnas.1418423111

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Chemists gain edge in next-gen energy: Flexible film can catalyze production of hydrogen

 

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A thin, flexible film developed at Rice University shows excellent potential as a hydrogen catalyst or as an energy storage device. The two-dimensional film could be a cost-effective component in such applications as fuel cells.

Rice University scientists who want to gain an edge in energy production and storage report they have found it in molybdenum disulfide.

The Rice lab of chemist James Tour has turned molybdenum disulfide's two-dimensional form into a nanoporous film that can catalyze the production of hydrogen or be used for energy storage.

The versatile chemical compound classified as a dichalcogenide is inert along its flat sides, but previous studies determined the material's edges are highly efficient catalysts for hydrogen evolution reaction (HER), a process used in fuel cells to pull hydrogen from water.

Tour and his colleagues have found a cost-effective way to create flexible films of the material that maximize the amount of exposed edge and have potential for a variety of energy-oriented applications.

The Rice research appears in the journal Advanced Materials.

Molybdenum disulfide isn't quite as flat as graphene, the atom-thick form of pure carbon, because it contains both molybdenum and sulfur atoms. When viewed from above, it looks like graphene, with rows of ordered hexagons. But seen from the side, three distinct layers are revealed, with sulfur atoms in their own planes above and below the molybdenum.

This crystal structure creates a more robust edge, and the more edge, the better for catalytic reactions or storage, Tour said.

"So much of chemistry occurs at the edges of materials," he said. "A two-dimensional material is like a sheet of paper: a large plain with very little edge. But our material is highly porous. What we see in the images are short, 5- to 6-nanometer planes and a lot of edge, as though the material had bore holes drilled all the way through."

The new film was created by Tour and lead authors Yang Yang, a postdoctoral researcher; Huilong Fei, a graduate student; and their colleagues. It catalyzes the separation of hydrogen from water when exposed to a current. "Its performance as a HER generator is as good as any molybdenum disulfide structure that has ever been seen, and it's really easy to make," Tour said.

While other researchers have proposed arrays of molybdenum disulfide sheets standing on edge, the Rice group took a different approach. First, they grew a porous molybdenum oxide film onto a molybdenum substrate through room-temperature anodization, an electrochemical process with many uses but traditionally employed to thicken natural oxide layers on metals.

The film was then exposed to sulfur vapor at 300 degrees Celsius (572 degrees Fahrenheit) for one hour. This converted the material to molybdenum disulfide without damage to its nano-porous sponge-like structure, they reported.

The films can also serve as supercapacitors, which store energy quickly as static charge and release it in a burst. Though they don't store as much energy as an electrochemical battery, they have long lifespans and are in wide use because they can deliver far more power than a battery. The Rice lab built supercapacitors with the films; in tests, they retained 90 percent of their capacity after 10,000 charge-discharge cycles and 83 percent after 20,000 cycles.

"We see anodization as a route to materials for multiple platforms in the next generation of alternative energy devices," Tour said. "These could be fuel cells, supercapacitors and batteries. And we've demonstrated two of those three are possible with this new material."

Co-authors of the paper are Rice graduate students Gedeng Ruan and Changsheng Xiang. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of materials science and nanoengineering and of computer science.

The Peter M. and Ruth L. Nicholas Postdoctoral Fellowship of Rice's Smalley Institute for Nanoscale Science and Technology and the Air Force Office of Scientific Research Multidisciplinary University Research program supported the research.

A future of power outages; what happens when the lights go out?

 

November 3, 2014

Taylor & Francis

It is impossible to imagine the modern world without electricity. We are dependent on an uninterrupted source of power and when it fails the consequences are devastating. Over the past decade there have been 50 significant power-outage events occurring in 26 countries, and the demand for electricity continues to grow stronger with rapid population growth, compact urban areas and an ‘addiction’ to electric appliances.

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It is impossible to imagine the modern world without electricity. We are dependent on an uninterrupted source of power and when it fails the consequences are devastating. Over the past decade there have been 50 significant power-outage events occurring in 26 countries, and the demand for electricity continues to grow stronger with rapid population growth, compact urban areas and an 'addiction' to electric appliances. In their article "Exergy and the City: The Technology and Sociology of Power (Failure)," Hugh Byrd and Steve Matthewman predict that these blackouts are only a dress rehearsal for a future in which they will appear more frequently and with greater severity.

The authors highlight the frail electrical power system of the 'privileged' West where it is taken for granted that there will be a continued stable supply of electricity for the distant future. Electrical power generation and distribution is more vulnerable than we might assume due to poor investment in infrastructure and many power grids operating close to capacity. Over the past 30 years, the demand for electricity has increased by 25%, while the construction of transmission faculties has fallen. It is argued that it will take large investments in electric utilities to meet future demand.

With our electrical infrastructures under threat, our dependence on electricity and our vulnerability when a blackout occurs are exposed; the economic damage of power outages and quality disturbances are estimated to cost the American economy between $25 and $180 billion per annum, although the indirect costs could be up to five times higher. Blackouts affect the economy and our everyday lives in a number of ways. Without electricity, food provisions are compromised as a lack of refrigeration means food cannot be stored safely, leading to increased risk of food poisoning; security systems fail and the crime rate increases, as it amplifies the opportunity for fraud, theft and exploitation. A lack of power also causes an immediate and prevalent problem for transport systems; traffic lights fail, rail systems come to a stop and air transport becomes compromised due to the loss of communications and unlit runways.

Despite a frail electrical infrastructure and the consequences of blackouts, our dependency on electricity continues to intensify, fuelled in part by consumer 'addictions' to electronic devices, air conditioning and, in the future electric vehicles. Electricity demands will become even greater as our resources become constrained due to the depletion of fossil fuel, a lack of renewable energy sources, peak oil and climate change. As we become more dependent on an uninterrupted supply of electricity for our comfort, security, communication systems, transport, health and food supply…what will happen when the lights go out?

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Story Source:

The above story is based on materials provided by Taylor & Francis. Note: Materials may be edited for content and length.

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Journal Reference:

1. Hugh Byrd, Steve Matthewman. Exergy and the City: The Technology and Sociology of Power (Failure). Journal of Urban Technology, 2014; 21 (3): 85 DOI: 10.1080/10630732.2014.940706

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O suicídio assistido da jovem dos Estados Unidos

O Vaticano, representado pelo sacerdote que condenou este ato, foi demagógico e incorreto.

Foi generalizada uma questão ética que neste caso não poderia ser vista assim. Todas as pessoas com um mínimo de cultura humanitária sabe que o suícidio é condenável. Porém deveria ter sido separado este caso da idéia veiculada pelo Vaticano.  Além de ser um caso de câncer raro e incurável, a jovem sofreria muito nos últimos tempos de sua vida já considerada terminal. Portanto, houve demagogia e houve incorreção. 

Não foi de modo algum um suicídio, assistido ou não.  São praticados processos de Eutanásia rotineiramente. Porém, tal processo é decidido pelos familiares, e este caso pode ser visto como um ato de Eutanásia decidida pela própria pessoa, e não de suicídio, uma vez que a jovem tinha consciência de seu estado e tinha também condições mentais para essa decisão.                                         

A palavra “suicídio” por si só já pressupõe uma atmosfera de desespero, e de conflitos extremos , onde práticamente não existe, exceto em raros casos, possibilidade de reflexão por parte da pessoa envolvida nesse trágico processo.

Completamente diferente do que foi o caso desta jovem. Portanto, a palavra “suicídio” não caberia aqui no sentido proposto pelo representante do Vaticano, e nem mesmo pelo autor original desse artigo.

 

José S de Melo

Os 7 países mais ricos do mundo

 

Lí um artigo no IExplorer, hoje, a lista dos 7 países mais ricos do mundo. Mas sem a renda per capita, não vale. China com um GDP de 17 trilhões mas com uma população de 1,3 ou 1,4 bilhões de pessoas.

Suponha 2 países com um GDP de US$ 2 trilhões. Um tem 20 milhões de habitantes, o segundo tem 60 milhões.  O mais rico aí é que tem menos habitantes, pois poderá dispor de mais verbas para educação e saúde, verbas para defesa, etc.  Existem outros fatores, mas esses dois são os principais e não podem estar desatrelados um do outro. Todos os fatores reunidos é que darão o resultado final sobre quem é de fato o mais rico….

José S de Melo

Beets

    

It is difficult to believe how the hardy, crunchy often rough looking exterior of raw beets can be transformed into something wonderfully soft and buttery once they are cooked. While beets are available throughout the year, their season runs from June through October when the youngest, most tender beets are easiest to find.
Edible green leaves are attached to the tapered round or oblong root portions that we know as beets. While we often think of beets having a reddish-purple hue, some varieties are white, golden-yellow or even rainbow colored. The sweet taste of beets reflects their high sugar content making them an important raw material for the production of refined sugar; they have the highest sugar content of all vegetables, yet are very low in calories

This chart graphically details the %DV that a serving of Beets provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Beets can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Beets, featuring information over 80 nutrients, can be found under the Food Rating System Chart.
Health Benefits
Remember all those legendary Russian centenarians? Beets, frequently consumed either pickled or in borscht, the traditional Russian soup, may be one reason behind their long and healthy lives. These colorful root vegetables contain powerful nutrient compounds that help protect against heart disease, birth defects and certain cancers, especially colon cancer.
Promote Optimal Health
The pigment that gives beets their rich, purple-crimson color-betacyanin-is also a powerful cancer-fighting agent. Beets' potential effectiveness against colon cancer, in particular, has been demonstrated in several studies.
In one study, animals under the double stress of chemically induced colon cancer and high cholesterol were divided into two groups. One group received a diet high in beet fiber while the other group served as a control. The beet fiber-fed animals rose to the challenge by increasing their activity of two antioxidant enzymes in the liver, glutathione peroxidase and glutathione-S-transferase. The liver is the body's primary detoxification organ where toxic substances are broken down and eliminated, a process that generates a lot of free radicals. Glutathione peroxidase and glutathione-S-transferase are the bodyguards for liver cells, protecting them from free radical attack, so they can continue to protect us.
In other animal studies, scientists have noted that animals fed beet fiber had an increase in their number of colonic CD8 cells, special immune cells responsible for detecting and eliminating abnormal cells. With the increased surveillance provided by these additional CD8 cells, the animals in one of the studies given beet fiber had fewer pre-cancerous changes.
In stomach cancer patients, when scientists compared the effects of fruit and vegetable juices on the formation of nitrosamines, cancer-causing compounds produced in the stomach from chemicals called nitrates, beet juice was found to be a potent inhibitor of the cell mutations caused by these compounds. Nitrates are commonly used as a chemical preservative in processed meats.
Protection Against Heart Disease
In the first study mentioned above, not only did protective antioxidant activity increase in the livers of beet fiber-fed animals, but also their total cholesterol dropped 30%, their triglycerides dropped 40% (elevated triglycerides, the form in which fats are transported in the blood, are a significant risk factor for cardiovascular disease), and their HDL (beneficial cholesterol) level increased significantly.
Beat High Blood Pressure with Beet Juice
Drinking just 2 glasses (16.9 ounces) of beetroot juice a day can significantly reduce blood pressure, shows a study in the American Heart Association journal Hypertension, which could have major implications for the treatment of cardiovascular disease. (Web AJ, Patel N, et al.)
Previously, the protective effects of vegetable-rich diets have been thought to be due to their content of antioxidant vitamins, but this study reveals that it is the dietary nitrate in beetroot juice - and in all green, leafy vegetables - whose consumption results in a decrease in blood pressure.
The nitrate in beet juice is converted by bacteria on the tongue into nitrite and swallowed in saliva, which, in the acidic environment of the stomach, is either converted into nitric oxide or re-enters the circulation as nitrite. Nitric oxide lowers blood pressure because it signals the endothelium (the lining of our blood vessels) to relax.
In healthy volunteers, blood pressure began to lessen within just 1 hour of drinking beet juice, with the peak drop of -10.48 mm/Hg occurring about 3 hours after ingestion. And beneficial blood pressure lowering effects continued to some degree for up to 24 hours!
Practical Tip: More than 25% of the world's adult population is currently hypertensive, a figure that is expected to increase to 29% by 2025. Since hypertension causes around 50% of coronary heart disease, and approximately 75% of strokes, toasting your health with a mid-morning and an early afternoon or evening glass of beet-rich vegetable juice or a cup of borscht is a daily habit that just might save your life or that of a loved one. A quick and easy recipe for Raw Borscht Soup can be found of page 248 of The World's Healthiest Foods.
Beets' Betaine Helps Lessen Inflammation
People whose diets supplied the highest average intake of choline (found in egg yolk and soybeans), and its metabolite betaine (found naturally in vegetables such as beets and spinach), have levels of inflammatory markers at least 20% lower than subjects with the lowest average intakes, report Greek researchers in the American Journal of Clinical Nutrition (Detopoulou P, Panagiotakos DB, et al.)
Compared to those whose diets contained <250 mg/day of choline, subjects whose diets supplied >310 mg of choline daily had, on average:
•    22% lower concentrations of C-reactive protein
•    26% lower concentrations of interleukin-6
•    6% lower concentrations of tumor necrosis factor alpha
Compared to those consuming <260 mg/day of betaine, subjects whose diets provided >360 mg per day of betaine had, on average:
•  10% lower concentrations of homocysteine
•  19% lower concentrations of C-reactive protein
•  12% lower concentrations of tumor necrosis factor alpha
Each of these markers of chronic inflammation has been linked to a wide range of conditions including heart disease, osteoporosis, cognitive decline and Alzheimer's, and type-2 diabetes.
In an accompanying editorial in the American Journal of Clinical Nutrition entitled, "Is there a new component of the Mediterranean diet that reduces inflammation?," Steven Zeisel from the University of North Carolina at Chapel Hill noted that choline and betaine work together in the cellular process of methylation, which is not only responsible for the removal of homocysteine, but is involved in turning off the promoter regions of genes involved in inflammation.
"Exposure to oxidative stress is a potent trigger for inflammation. Betaine is formed from choline within the mitochondria , and this oxidation contributes to mitochondrial redox status ," Zeisel continued.

"If the association between choline and betaine and inflammation can be confirmed in studies of other populations, an interesting new dietary approach may be available for reducing chronic diseases associated with inflammation," he concluded.
Recommended daily intakes of choline were set in 1998 at 550 milligrams per day for men and 425 milligrams a day for women. No RDI has been set for betaine, which, since it is a metabolite of choline, is not considered an essential nutrient.
Practical Tip: Egg yolks are the richest source of choline, followed by soybeans. Beets, spinach and whole wheat products are primary sources of betaine. (Olthof MR, van Vliet T, et al. J Nutr)
Protection against Birth Defects
Beets are particularly rich in the B vitamin folate, which is essential for normal tissue growth. Eating folate-rich foods is especially important during pregnancy since without adequate folate, the infant's spinal column does not develop properly, a condition called neural tube defect. The daily requirement for folate is 400 micrograms. Just one cup of boiled, sliced beets contains 136 micrograms of folate.
Description
Both beets and Swiss chard are different varieties within the same plant family (Amaranthaceae-Chenopodiaceae) and their edible leaves share a resemblance in both taste and texture. Attached to the beet's green leaves is a round or oblong root, the part conjured up in most people's minds by the word "beet." Although typically a beautiful reddish-purple hue, beets also come in varieties that feature white or golden roots. No matter what their color, however, beet roots aren't as hardy as they look; the smallest bruise or puncture will cause red beets' red-purple pigments, which contain beneficial flavonoids called anthycyanins, to bleed, especially during cooking.
Beets' sweet taste reflects their high sugar content, which makes beets an important source for the production of refined sugar. Raw beet roots have a crunchy texture that turns soft and buttery when they are cooked. Beet leaves have a lively, bitter taste similar to chard. The main ingredient in the traditional eastern European soup, borscht, beets are delicious eaten raw, but are more typically cooked or pickled.
The greens attached to the beet roots are delicious and can be prepared like spinach or Swiss chard. They are incredibly rich in nutrients, concentrated in vitamins and minerals as well as carotenoids such as beta-carotene and lutein/zeaxanthin.
History
The wild beet, the ancestor of the beet with which we are familiar today, is thought to have originated in prehistoric times in North Africa and grew wild along Asian and European seashores. In these earlier times, people exclusively ate the beet greens and not the roots. The ancient Romans were one of the first civilizations to cultivate beets to use their roots as food. The tribes that invaded Rome were responsible for spreading beets throughout northern Europe where they were first used for animal fodder and later for human consumption becoming more popular in the 16th century.
Beets' value grew in the 19th century when it was discovered that they were a concentrated source of sugar, and the first sugar factory was built in Poland. When access to sugar cane was restricted by the British, Napoleon decreed that the beet be used as the primary source of sugar, catalyzing its popularity. Around this time, beets were also first brought to the United States, where they now flourish. Today the leading commercial producers of beets include the United States, the Russian Federation, France, Poland, France and Germany.
How to Select and Store
Choose small or medium-sized beets whose roots are firm, smooth-skinned and deep in color. Smaller, younger beets may be so tender that peeling won't be needed after they are cooked.
Avoid beets that have spots, bruises or soft, wet areas, all of which indicate spoilage. Shriveled or flabby should also be avoided as these are signs that the roots are aged, tough and fibrous.
While the quality of the greens does not reflect that of the roots, if you are going to consume this very nutritious part of the plant, look for greens that appear fresh, tender, and have a lively green color.
Store beets unwashed in the refrigerator crisper where they will keep for two to four weeks. Cut the majority of the greens and their stems from the roots, so they do not pull away moisture away from the root. Leave about two inches of the stem attached to prevent the roots from "bleeding." Store the unwashed greens in a separate plastic bag where they will keep fresh for about four days.
Raw beets do not freeze well since they tend to become soft upon thawing. Freezing cooked beets is fine; they'll retain their flavor and texture.
How to Enjoy
Tips for Preparing Beets:
Cook beets lightly. Studies show beets' anti-cancer activity is diminished by heat.
Don't peel beets until after cooking. When bruised or pierced, beets bleed, losing some of their vibrant color and turning a duller brownish red. To minimize bleeding, wash beets gently under cool running water, taking care not to tear the skin since this tough outer layer helps keep most of beets' pigments inside the vegetable. To prevent bleeding when boiling beets, leave them whole with their root ends and one inch of stem attached.
Beets' color can be modified during cooking. Adding an acidic ingredient such as lemon juice or vinegar will brighten the color while an alkaline substance such as baking soda will often cause them to turn a deeper purple. Salt will blunt beets' color, so add only at the end of cooking if needed.
Since beet juice can stain your skin, wearing kitchen gloves is a good idea when handling beets. If your hands become stained during the cleaning and cooking process, simply rubbing some lemon juice on them will remove the stain.
A Few Quick Serving Ideas:
Simply grate raw beets for a delicious and colorful addition to salads or decorative garnish for soups.
Add chunks of beet when roasting vegetables in the oven.
Serving homemade vegetable juice? A quarter of a beet will turn any green drink into a sweet pink concoction, pleasing both the eyes and the taste buds.
Healthy sauté beet greens with other braising greens such as chard and mustard greens.
Marinate steamed beets in fresh lemon juice, olive oil, and fresh herbs.
Safety
Beeturia
If you start to see red when you increase your consumption of beets, don't be alarmed. You're just experiencing beeturia, or a red or pink color to your urine or stool. No need to panic; the condition is harmless.
Beets and Oxalates
Beets (notably beet greens) are among a small number of foods that contain measurable amounts of oxalates, naturally-occurring substances found in plants, animals, and human beings. When oxalates become too concentrated in body fluids, they can crystallize and cause health problems. For this reason, individuals with already existing and untreated kidney or gallbladder problems may want to avoid eating beets. Laboratory studies have shown that oxalates may also interfere with absorption of calcium from the body. Yet, in every peer-reviewed research study we've seen, the ability of oxalates to lower calcium absorption is relatively small and definitely does not outweigh the ability of oxalate-containing foods to contribute calcium to the meal plan. If your digestive tract is healthy, and you do a good job of chewing and relaxing while you enjoy your meals, you will get significant benefits - including absorption of calcium - from calcium-rich foods plant foods that also contain oxalic acid. Ordinarily, a healthcare practitioner would not discourage a person focused on ensuring that they are meeting their calcium requirements from eating these nutrient-rich foods because of their oxalate content. For more on this subject, please see "Can you tell me what oxalates are and in which foods they can be found?"

Nutritional Profile
Beets are an excellent source of the B vitamin, folate, and a very good source of manganese and potassium. Beets are a good source of dietary fiber, vitamin C, magnesium, iron, copper and phosphorus.
For an in-depth nutritional profile click here: Beets.

In-Depth Nutritional Profile
In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Beets is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.
Introduction to Food Rating System Chart
In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

Beets, Boiled
1.00 cup
170.00 grams
74.80 calories
Nutrient    Amount    DV
(%)    Nutrient
Density    World's Healthiest
Foods Rating
folate    136.00 mcg    34.0    8.2    excellent
manganese    0.55 mg    27.5    6.6    very good
potassium    518.50 mg    14.8    3.6    very good
dietary fiber    3.40 g    13.6    3.3    good
vitamin C    6.12 mg    10.2    2.5    good
magnesium    39.10 mg    9.8    2.4    good
tryptophan    0.03 g    9.4    2.3    good
iron    1.34 mg    7.4    1.8    good
copper    0.13 mg    6.5    1.6    good
phosphorus    64.60 mg    6.5    1.6    good
World's Healthiest
Foods Rating    Rule
excellent    DV>=75%    OR    Density>=7.6    AND    DV>=10%
very good    DV>=50%    OR    Density>=3.4    AND    DV>=5%
good    DV>=25%    OR    Density>=1.5    AND    D

Abacate, uma das melhores frutas para sua saúde.

Avocados

Although the creamy rich Hass avocados are generally available throughout the year, they are the most abundant and at their best during the spring and summer in California and in October in Florida. During the fall and winter months you can find Fuerto, Zutano and Bacon varieties.

The avocado is colloquially known as the Alligator Pear, reflecting its shape and the leather-like appearance of its skin. Avocado is derived from the Aztec word "ahuacatl".

Health Benefits

Promote Heart Health

Avocados contain oleic acid, a monounsaturated fat that may help to lower cholesterol. In one study of people with moderately high cholesterol levels, individuals who ate a diet high in avocados showed clear health improvements. After seven days on the diet that included avocados, they had significant decreases in total cholesterol and LDL cholesterol, along with an 11% increase in health promoting HDL cholesterol.

Abacates contém ácido oléico, uma gordura monoinsaturada, que pode ajudar a diminuir o colesterol. Em um estudo em pessoas com níveis moderados de colesterol, pessoas que comeram bastante abacates mostraram claros sinais de melhoria na saúde. Depois de sete dias de dieta, incluindo abacates, eles tiveram significaticas reduções no colesterol total e no colesterol LDL, junto com um aumento de 11% no colesterol HDL, que é o bom.

Avocados are a good source of potassium, a mineral that helps regulate blood pressure. Adequate intake of potassium can help to guard against circulatory diseases, like high blood pressure, heart disease or stroke. In fact, the U.S. Food and Drug Association has authorized a health claim that states: "Diets containing foods that are good sources of potassium and low in sodium may reduce the risk of high blood pressure and stroke."

Os abacates são uma boa fonte de potássio, um mineral que ajuda a regular a pressão sanguínea. Ingestão adequada de potássio pode ajudar a defender distúrbios circulatórios, como pressão alta, doenças cardíacas e infartos. Realmente, o FDA, autorizou uma afirmação em questões de saúde que afirma : Dietas contendo alimentos que tem boas fontes de potássio e baixas em sódio, podem reduzir o risco de pressão alta e infarto.

One cup of avocado has 23% of the Daily Value for folate, a nutrient important for heart health. To determine the relationship between folate intake and heart disease, researchers followed over 80,000 women for 14 years using dietary questionnaires. They found that women who had higher intakes of dietary folate had a 55% lower risk of having heart attacks or fatal heart disease. Another study showed that individuals who consume folate-rich diets have a much lower risk of cardiovascular disease or stroke than those who do not consume as much of this vital nutrient.

Uma xícara de abacate tem 23% um valôr diário de 23% de folatos, um nutriente muito importante para a saúde do coração. Para determinar a relalão entre a ingestão de folatos e doenças cardíacas, pesquisadores acompanharam 80.000 mulheres durante 14 anos usando questionários dietéticos. Eles descobriram que as mulheres que ingeriram maiores quantidades de folatos, tiveram 55% menos riscos de terem atques cardíacos ou denças cardíacas fatais. Um outro estudo mostrou que as pessoas que consomem dietas ricas em folatos, tem muito menos riscos de doenças cardiovasculares ou infartos do que aqueles que não consomem o suficiente deste nutriente vital.

Promote Optimal Health

Not only are avocados a rich source of monounsaturated fatty acids including oleic acid, which has recently been shown to offer significant protection against breast cancer, but it is also a very concentrated dietary source of the carotenoid lutein; it also contains measurable amounts of related carotenoids (zeaxanthin, alpha-carotene and beta-carotene) plus significant quantities of tocopherols (vitamin E).

Não sómente abacates são ricas fontes de ácidos gordurosos monoinsaturados, incluindo ácido oléico, que recentemente tem mostrado oferecer uma significativa proteção contra o câncer de mama, mas também é uma fonte concentrada do carotenóide luteína; Contém também quantidades mensuráveis de carotenóides relacionados ( zeawantina, alfa-caroteno, e beta-caroteno) mais quantidades significativas de vitamina E.

In a laboratory study published in the Journal of Nutritional Biochemistry, an extract of avocado containing these carotenoids and tocopherols inhibited the growth of both androgen-dependent and androgen-independent prostate cancer cells.

But when researchers tried exposing the prostate cancer cells to lutein alone, the single carotenoid did not prevent cancer cell growth and replication. Not only was the whole matrix of carotenoids and tocopherols in avocado necessary for its ability to kill prostate cancer cells, but the researchers also noted that the significant amount of monounsaturated fat in avocado plays an important role. Carotenoids are lipid (fat)-soluble, which means fat must be present to ensure that these bioactive carotenoids will be absorbed into the bloodstream. Just as Nature intends, avocado delivers the whole heath-promoting package.

Increase Your Absorption of Carotenoids from Vegetables

Enjoying a few slices of avocado in your tossed salad, or mixing some chopped avocado into your favorite salsa will not only add a rich, creamy flavor, but will greatly increase your body's ability to absorb the health-promoting carotenoids that vegetables provide.

A study published in the March 2005 issue of the Journal of Nutrition tested the hypothesis that since carotenoids are lipophilic (literally, fat-loving, which means they are soluble in fat, not water), consuming carotenoid-rich foods along with monounsaturated-fat-rich avocado might enhance their bioavailability.

Not only did adding avocado to a salad of carrot, lettuce and baby spinach or to salsa greatly increase study participants' absorption of carotenoids from these foods, but the improvement in carotenoid availability occurred even when a very small amount-as little as 2 ounces-of avocado was added.

Adding avocado to salad increased absorption of alpha-carotene, beta-carotene and lutein 7.2, 15.3, and 5.1 times higher, respectively, than the average amount of these carotenoids absorbed when avocado-free salad was eaten.

Adding avocado to salsa increased lycopene and beta-carotene absorption 4.4 and 2.6 times higher, respectively, than the average amount of these nutrients absorbed from avocado-free salsa. Since avocados contain a large variety of nutrients including vitamins, minerals, as well as heart-healthy monounsaturated fat, eating a little avocado along with carotenoid-rich vegetables and fruits is an excellent way to improve your body's ability to absorb carotenoids while also receiving other nutritional-and taste-benefits.

Avocado Phytonutrients Combat Oral Cancer

Oral cancer is even more likely to result in death than breast, skin, or cervical cancer, with a mortality rate of about 50% due to late detection, according to Great Britain's Mouth Cancer Foundation. Avocados may offer a delicious dietary strategy for the prevention of oral cancer. Phytonutrients in Hass avocados, the most readily available of the more than 500 varieties of avocados grown worldwide, target multiple signaling pathways, increasing the amount of free radicals (reactive oxygen species) within pre-cancerous and cancerous human oral cell lines, that leads to their death, but cause no harm to normal cells. ? Semin Cancer Biol. 2007 May 17. Earlier research by UCLA scientists also indicates that Hass avocados may inhibit the growth of prostate cancer as well. When analyzed, Hass avocados were found to contain the highest content of lutein among commonly eaten fruits as well as measurable amounts of related carotenoids (zeaxanthin, alpha-carotene, and beta-carotene). Lutein accounted for 70% of the measured carotenoids, and the avocado also contained significant quantities of vitamin E. J Nutr Biochem. 2005 Jan;16(1):23-30.

Description

The avocado is colloquially known as the Alligator Pear, reflecting its shape and the leather-like appearance of its skin. Avocado is derived from the Aztec word "ahuacatl."

Avocados are the fruit from the Persea Americana, a tall evergreen tree that can grow up to 65 feet in height. There are dozens of varieties of avocadoes, which fall into three main categories-Mexican, Guatemalean, and West Indian-which differ in their size, appearance, quality and susceptibility to cold. The most popular type of avocado in the United States is the Hass variety, which has rugged, pebbly brown-black skin. Another common type of avocado is the Fuerte, which is larger than the Hass and has smooth, dark green skin and a more defined pear shape.

Avocados vary in weight from 8 ounces to 3 pounds depending upon the variety. The edible portion of the avocado is its yellow-green flesh, which has a luscious, buttery consistency and a subtle nutty flavor. The skin and pit are inedible.

History

Avocados are native to Central and South America and have been cultivated in these regions since 8,000 B.C. In the mid-17th century, they were introduced to Jamaica and spread through the Asian tropical regions in the mid-1800s. Cultivation in United States, specifically in Florida and California, began in the early 20th century. While avocados are now grown in most tropical and subtropical countries, the major commercial producers include the United States (Florida and California), Mexico, the Dominican Republic, Brazil and Colombia.

How to Select and Store

A ripe, ready to eat avocado is slightly soft but should have no dark sunken spots or cracks. If the avocado has a slight neck, rather than being rounded on top, it was probably tree ripened and will have better flavor. A firmer, less mature fruit can be ripened at home and will be less likely to have bruises. The Hass avocado weighs about 8 ounces on average and has a pebbled dark green or black skin, while the Fuerte avocado has smoother, brighter green skin. Avoid Fuertes with skin that is too light and bright. Florida avocados, which can be as large as 5 pounds, have less fat and calories, but their taste is not as rich as California varieties.

A firm avocado will ripen in a paper bag or in a fruit basket at room temperature within a few days. As the fruit ripens, the skin will turn darker. Avocados should not be refrigerated until they are ripe. Once ripe, they can be kept refrigerated for up to a week. If you are refrigerating a whole avocado, it is best to keep it whole and not slice it in order to avoid browning that occurs when the flesh is exposed to air.

If you have used a portion of a ripe avocado, it is best to store the remainder in the refrigerator. Store in a plastic bag, wrap with plastic wrap, or place on a plate and cover with plastic wrap. Sprinkling the exposed surface(s) with lemon juice will help to prevent the browning that can occur when the flesh comes in contact with oxygen in the air.

How to Enjoy

For some of our favorite recipes, click Recipes

Tips for preparing avocados:

Use a stainless steel knife to cut the avocado in half lengthwise. Gently twist the two halves in opposite direction if you find the flesh clinging to the pit. Remove the pit, either with a spoon or by spearing with the tip of a knife. Place the halves face down, then peel and slice. If the flesh is too soft to be sliced, just slide a spoon along the inside of the skin and scoop it out. You can prevent the natural darkening of the avocado flesh that occurs with exposure to air by sprinkling with a little lemon juice or vinegar.

A few quick serving ideas:

Use chopped avocados as a garnish for black bean soup.

Add avocado to your favorite creamy tofu-based dressing recipe to give it an extra richness and beautiful green color.

Mix chopped avocados, onions, tomatoes, cilantro, lime juice and seasonings for a rich-tasting twist on traditional guacamole.

Spread ripe avocados on bread as a healthy replacement for mayonnaise when making a sandwich.

For an exceptional salad, combine sliced avocado with fennel, oranges and fresh mint.

For a beautiful accompaniment to your favorite Mexican dish, top quartered avocado slices with corn relish and serve with a wedge of lime.

Safety

Avocados and Latex Allergy

Like bananas and chestnuts, avocados contain substances called chitinases that are associated with the latex-fruit allergy syndrome. There is strong evidence of the cross-reaction between latex and these foods. If you have a latex allergy, you may very likely be allergic to these foods as well. Processing the fruit with ethylene gas increases these enzymes; organic produce not treated with gas will have fewer allergy-causing compounds. In addition, cooking the food may deactivate the enzymes.

Nutritional Profile

Avocados are a good source of vitamin K, dietary fiber, vitamin B6, vitamin C, folate and copper. Avocados are also a good source of potassium: they are higher in potassium than a medium banana.

Although they are fruits, avocados have a high fat content of between 71 to 88% of their total calories - about 20 times the average for other fruits. A typical avocado contains 30 grams of fat, but 20 of these fat grams are health-promoting monounsaturated fats, especially oleic acid.

For an in-depth nutritional profile click here: Avocado.

In-Depth Nutritional Profile

In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Avocados is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.

Introduction to Food Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

Avocado, slices 1.00 cup 146.00 grams 235.06 calories Nutrient Amount DV (%) Nutrient Density World's Healthiest Foods Rating vitamin K 29.20 mcg 36.5 2.8 good dietary fiber 7.30 g 29.2 2.2 good potassium 874.54 mg 25.0 1.9 good folate 90.37 mcg 22.6 1.7 good vitamin B6 (pyridoxine) 0.41 mg 20.5 1.6 good vitamin C 11.53 mg 19.2 1.5 good copper 0.38 mg 19.0 1.5 good World's Healthiest Foods Rating Rule excellent DV>=75% OR Density>=7.6 AND DV>=10% very good DV>=50% OR Density>=3.4 AND DV>=5% good DV>=25% OR Density>=1.5 AND DV>=2.5%