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(Health) Vitamin C: Oranges

 
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adedios
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PostPosted: Wed Dec 21, 2005 11:43 am    Post subject: (Health) Vitamin C: Oranges Reply with quote






Superfoods: Oranges
Mariam Alireza, Arab News

JEDDAH, 21 December 2005 — You must be wondering why ordinary everyday foods are called Superfoods.

They are considered special because of their abundance in necessary nutrients to maintain optimum health.

The good news is that most of them are readily available in most markets around the country. The subject of our story today is the common fruit, oranges.

Oranges and the rest of the citrus family, lemons, white and pink grapefruit, kumquats, limes, and tangerines are known for their richness in vitamin C. But, the exciting aspect about this fruit is its other less publicized phytochemicals like limonene, pectin, potassium, fiber, and variety of polyphenols, vitamin B12, B6, folate, and betaine.

Oranges and citrus fruits have long been known for their richness in vitamin C.

The fruit saved sailors from dying of scurvy during endless voyages at sea centuries ago. Because the body does not make the vitamin, we need a regular dietary supplement from oranges or other C-rich fruits.

However, when the fruit is unavailable supplements are important to take daily. There is no fear of overdosing on the nutrient as it is water-soluble and is rapidly excreted from the body.

The multi-faceted efficacy of vitamin C demands its continuous dietary supplement, as it is also a cofactor to many nutrients and protective to health at the cellular level.

Therefore, vitamin C dietary supplementation is necessary to ensure the proper functioning of many body organs including the heart, vascular system, cells, eyes, bones, tissues, skin, and others.

Additionally, vitamin C in oranges and citrus fruits prevents certain cancers like mouth, stomach, and colon, which are triggered by cancer-causing agents, nitrosamines, added to certain foodstuffs.

Naringin in grapefruit and hesperdin in orange are flavonoids exclusively found in the citrus family. These polyphenols act as antimutigens, inhibiting the mutation of cells, thus cancer and other chronic diseases.

These flavonoids along with rutin in the fruit and black currants possess anti-inflammatory, antiallergenic, antiviral, and antibacterial actions.

They also strengthen blood vessels, lowering risk of heart attack and stroke. Hesperdin regenerates vitamin C after it neutralizes free radicals; it is known to enhance the vitamin.

The flavonoid has other benefits; it reduces “bad” cholesterol in the blood and increases “good” cholesterol.

A glass of orange juice with its pulp is found to lower risk of heart disease and stroke and improve cardiovascular disorders. Polyphenols in the fruit have protective substances against stroke.

So do not rely only on isolated vitamin C supplement for protection, but rather on all the nutrients in the whole fruit. The supplement should not replace the real thing that supplies multiple nutrients unless your physician advises you to do so.

Pectin, the white lining of citrus fruit, is a dietary soluble fiber that lowers cholesterol and also inhibits cancer growths and their proliferation.

Orange fiber is associated with lower incident of heart disease. The dietary fiber in tangerines is the best source of pectin to reduce cholesterol and control blood sugar levels.

Pectin seems to balance blood sugar levels by reducing glucose absorption, resulting in a lower insulin secretion in diabetic patients.

The fact that the whole fruit offers anticancer agents makes it an excellent choice of nutrition to maintain overall health and prevent the spreading of prostate, melanoma, and other cancers.

The oil in the peel of oranges and citrus family contains a phytonutrient called limonene. This phytochemical activates the body’s detoxifying enzymes to suppress cancer effects on cells and make tumors shrink in size.

To enhance the flavor of your cooking, add lemon or orange zest to salad dressings, meat or poultry stews, orange juice, lemonade, syrups, and desserts.

Remember to wash the fruit thoroughly with warm water and very little liquid soap if it is not organic.

Folate, a member of the vitamin B family, has a preventive action on cardiovascular disease by lowering homocysteine, a harmful compound in the circulatory system. The nutrient in oranges preserves the cell’s DNA and helps protect against colon, cervical, and probably breast cancers.

Flavonoids are available in most fruits, vegetables, legumes, nuts, seeds, grains, tea, and herbs. There are thousands of these phytonutrients identified through scientific research.

To our advantage, they are very abundant in citrus fruits.

These health-promoting phytochemicals are located in the fruit’s tissue, juice, pulp, and peel, making the consumption of the whole fruit much more health providing than the juice alone.

To benefit from citrus fruits, include them in your daily diet. Eat the whole fruit or drink its juice.

You can have the juice with pulp or add segments of the fruit to a smoothie, sorbet, ice-cream, yogurt, and fruit salad, chicken casserole, the gravy of duck, or vegetable salads. The juice and the zest make a good salad dressing and cake and cheesecake mixtures. The Chinese add orange zest to their tea to make an enjoyable cup of tea full of nutrients.

The French prepare duck a l’orange to counteract saturated fat with orange benefits.

A glass of orange juice or lemonade is nourishing after an exercise session or on a hot day.

It is up to you to choose how to eat or drink your citrus fruit or juice, but please do take it regularly to protect your heart and maintain sound health full of energy.

************************************************************

Questions to explore further this topic:

What are citrus fruits?

http://www.contentotrade.com/Terpene/eng/l'agrume.htm

Here are photos of various citrus fruits:

http://waynesword.palomar.edu/ecoph6.htm
http://www.tradewindsfruit.com/citrus.htm

Do citrus fruits contain Vitamin C?

http://www.ultimatecitrus.com/vitaminc.html
http://www.knet.co.za/orangent/citrus_juice.htm

How is orange juice harvested and processed?

http://members.aol.com/citrusweb/oj_story.html

What is vitamin C?

http://www.mothernature.com/Li.....id/2929001
http://www.pennhealth.com/ency/article/002404.htm

What is vitamin B?

http://www.vitaminsdiary.com/vitamin-b-complex.htm

What are bioflavonoids?

http://www.vitaminsdiary.com/bioflavonoids.htm

GAMES

http://vickids.tamu.edu/nutrition/fungames.html
http://www.dole5aday.com/MusicAndPlay/M_Games.jsp
http://www.sunkist.com/kids/games/


Last edited by adedios on Sat Jan 27, 2007 4:50 pm; edited 2 times in total
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PostPosted: Mon Dec 26, 2005 7:06 am    Post subject: Reply with quote

Grapefruit may cut gum disease


LONDON (BBC Health News) -- Eating grapefruit could help fight gum disease, a study suggests.

Researchers found people with gum disease who ate two grapefruits a day for a fortnight showed significantly less bleeding from the gums.

They believe this is due to an increase in blood levels of vitamin C, known to promote wound healing and cut damage by unstable free radical molecules.

The research, by Friedrich Schiller University in Germany, is published in the British Dental Journal.

The study of 58 people with chronic gum disease found that eating grapefruits had a positive effect on both smokers and non-smokers.

Smoking is known to increase the risk of gum disease.

At the start of the two-week study, virtually all those taking part had low levels of vitamin C in their blood plasma.

On average smokers' vitamin C level was 29% lower than that for non-smokers. Eating two grapefruits a day raised vitamin C plasma levels for all those who consumed it.

In smokers, the level almost doubled, but because they started from a lower baseline their average vitamin C level was still lower than that recorded in the non-smokers.

It is unclear why smoking is associated with lower vitamin C levels. It is possible that it alters the way the body metabolizes the vitamin, but it is also possible that smokers tend to have a less healthy diet.

Tooth loss

Dr. Gordon Watkins, a scientific advisor to the British Dental Association, told the BBC News website that gum disease was a major problem in the UK.

"Most people have a small amount of gum disease, much of which is reversible," he said.

"But a significant amount have intractable gum disease, which is the biggest cause of loss of teeth in adults.

"This is a small-scale, short-term study but it reinforces the message that if you have enough vitamin C in your diet then it tends to promote healing."

Dr. Watkins said that a healthy, balanced diet should provide enough vitamin C.

However, he stressed that the body was unable to store up excess amounts of the vitamin, so a steady intake was important.

Each grapefruit contains approximately 92.5 mg of vitamin C.

Those taking part in the research were advised to brush their teeth immediately after consuming the grapefruits.

This is because citrus fruits are acidic and can weaken tooth enamel making it susceptible to erosion.
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PostPosted: Sat Jan 14, 2006 9:09 am    Post subject: Need a boost? Zest assured Reply with quote

Need a boost? Zest assured
By Jane Clarke
At your table: citrus

I can never have too many clementines, satsumas and oranges at this time of year. My body craves their uplifting cool juiciness. I’ve even started copying my parents and having half a grapefruit for breakfast, although I prefer the slightly sweeter pink variety. I find the yellow ones are a bit too acidic on an empty stomach.
Pink grapefruit is delicious grilled with soft brown sugar. If you have any star anise, you can crush up a couple with the sugar to add a slightly aniseed/liquorice flavour. Sprinkle the sugar over the top of the cut grapefruit and put it under a medium-hot grill for about five minutes, until the sugar caramelises and the grapefruit becomes tinged. Watch carefully, as the sugar can burn easily. This is yummy served with Greek-style natural yoghurt.



To some extent I think our bodies crave the thing they need — not an excuse for continuing to tuck into chocolates. January is commonly when we fall prey to colds and flu, so it’s important to ensure that we get enough of nutrients such as vitmain C that will help to minimise our chances of catching a virus. We also need plenty of vitamin C, aka ascorbic acid, because it influences the production of the protein collagen , which we need for healthy structure and the funtion of connective tissues such as skin.

It is also involved in the structure and function of blood vessels and in neurological function. This vitamin has antioxidant capabilities, protecting cells from damage which can lead to the development of heart disease, accelerate ageing and cause some cancers.

But this doesn’t mean you should rush out and buy a vitamin C supplement, An orange contains about 86mg of vitamin C per fruit, which is well over the EU’s recommended daily amount (RDA) of 60mg a day. We just don’t need 1,000 or 2,000mg of vitamin C. I know this is contrary to the supplement manufacturers’ claims, but you are throwing your money down the toilet, and I have seen cases in my practice of people suffering from IBS symptoms and mouth ulcers as a result of taking vitamin C supplements.

Smokers are the exception because cigarettes put the body under oxidative stress. They need about 2,000mg of vitamin C a day and as it’s hard to get this quantity from a normal diet, a supplement is a good idea.

Most citrus fruits — oranges, grapefruits, lemons — contain good amounts of vitamin C; just half a grapefruit a day gives us enough to cover our needs. But tangerines, satsumas, mandarins and clementines aren’t great at providing us with this antioxidant nutrient. Mandarins and satsumas are varieties of the small, sweet tangerine, and the very similar clementine is thought to be a hybrid between the tangerine and the sweet orange.

The vitamin C in limes is famed thanks to British sailors, who used to eat them to prevent the skin disease scurvy, earning them the nickname “limeys”. In fact, of all the citrus fruit, limes are one of the lowest in vitamin C: the juice from half a lime tots up to only 4mg of vitamin C.

Oranges and lemons are also good sources of pectin, a soluble fibre that has a cholesterol-lowering effect. Pink grapefruit is rich in beta-carotene, which can help to protect our bodies against heart disease and cancer. But like oranges and yellow grapefruit, you get the most benefit from eating some of the white pith. This is the part of citrus fruits that’s richest in the pectin and the bioflavonoid hersperidin, which, along with other flavonoids, provides one of the most exciting areas of anti-cancer nutritional research. So don’t peel them too carefully.
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PostPosted: Mon Jan 16, 2006 9:42 pm    Post subject: vitamin C Reply with quote

adedios wrote:
Grapefruit may cut gum disease


LONDON (BBC Health News) -- Eating grapefruit could help fight gum disease, a study suggests.

Researchers found people with gum disease who ate two grapefruits a day for a fortnight showed significantly less bleeding from the gums.

They believe this is due to an increase in blood levels of vitamin C, known to promote wound healing and cut damage by unstable free radical molecules.

The research, by Friedrich Schiller University in Germany, is published in the British Dental Journal.

The study of 58 people with chronic gum disease found that eating grapefruits had a positive effect on both smokers and non-smokers.

Smoking is known to increase the risk of gum disease.

At the start of the two-week study, virtually all those taking part had low levels of vitamin C in their blood plasma.

On average smokers' vitamin C level was 29% lower than that for non-smokers. Eating two grapefruits a day raised vitamin C plasma levels for all those who consumed it.

In smokers, the level almost doubled, but because they started from a lower baseline their average vitamin C level was still lower than that recorded in the non-smokers.

It is unclear why smoking is associated with lower vitamin C levels. It is possible that it alters the way the body metabolizes the vitamin, but it is also possible that smokers tend to have a less healthy diet.

Tooth loss

Dr. Gordon Watkins, a scientific advisor to the British Dental Association, told the BBC News website that gum disease was a major problem in the UK.

"Most people have a small amount of gum disease, much of which is reversible," he said.

"But a significant amount have intractable gum disease, which is the biggest cause of loss of teeth in adults.

"This is a small-scale, short-term study but it reinforces the message that if you have enough vitamin C in your diet then it tends to promote healing."

Dr. Watkins said that a healthy, balanced diet should provide enough vitamin C.

However, he stressed that the body was unable to store up excess amounts of the vitamin, so a steady intake was important.

Each grapefruit contains approximately 92.5 mg of vitamin C.

Those taking part in the research were advised to brush their teeth immediately after consuming the grapefruits.

This is because citrus fruits are acidic and can weaken tooth enamel making it susceptible to erosion.


Yes true prof.. thats why i love eating citrus fruits especially oranges..but im not fond drinking artificial fruit juices contain vitamin C.
______________
arlene alegre
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PostPosted: Thu Jan 19, 2006 10:52 am    Post subject: Reply with quote

Arlene,

I am happy that you made your presence felt here in this forum. I request that you encourage your fellow teachers to visit this forum and initiate discussion. Many many thanks, in advance.

-Angel
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PostPosted: Wed Feb 01, 2006 10:51 am    Post subject: Reply with quote

Very Happy Hi Prof.Angel,
Thanks for the "info" about Oranges,I love eating fresh oranges...What about "fresh pineapple",does it also contains vitamin c?...because I"m very fond also of eating that fruit...I really enjoyed reading the topic about "oranges"...Thank you so much Prof.Angel.

Btw,congratz nga po pala sa inyong 2 ni Mary on your coming baby...God bless.

Thanks & Regards,
Ten Wink Wink Wink
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PostPosted: Wed Feb 01, 2006 11:28 am    Post subject: Reply with quote

Here, Ten, is the analysis of the nutritional contents of pineapple:

http://www.nutritiondata.com/f.....c20WZ.html
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PostPosted: Thu Feb 02, 2006 10:06 am    Post subject: Reply with quote

Smile Good day,Prof.Angel,
Thank you so much for the info about "pineapple","watermelon" etc....i'll try to read them one by one later.
Take care & God bless you,Mary & your coming baby.

Thanks & Regards,
10 Wink

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PostPosted: Sat Aug 12, 2006 7:28 am    Post subject: Juice May Slow Prostate Cancer Growth (with recipe) Reply with quote

Week of Aug. 12, 2006; Vol. 170, No. 7

Juice May Slow Prostate Cancer Growth (with recipe)
Janet Raloff

Prostate cancer will claim the lives of an estimated 30,000 men in the United States this year. The second leading cause of cancer death in men, its incidence climbs with age. In Western countries, the disease is reaching nearly epidemic proportions among the elderly. However, the cancer can grow so slowly that many men with prostate cancer will die of something else first.

A mystery has always been what factors might improve a man's odds of having a slow-growing malignancy. A new study suggests that drinking pomegranate juice might be one of them.


For the full article:

http://www.sciencenews.org/art.....2/food.asp
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PostPosted: Thu Oct 26, 2006 7:07 am    Post subject: Vitamin C and water not just healthy for people Reply with quote

National Science Foundation
25 October 2006

Vitamin C and water not just healthy for people -- healthy for plastics, too

New manufacturing techniques may lead to cheaper, 'greener' plastics
Two new laboratory breakthroughs are poised to dramatically improve how plastics are made by assembling molecular chains more quickly and with less waste. Using such environmentally friendly substances as vitamin C or pure water, the two approaches present attractive alternatives to the common plastic manufacturing technique called free radical polymerization (FRP).

"The methods both present novel and complementary ways to dramatically improve efficiency, product control, and cost for the polymer industry," said Andy Lovinger, the National Science Foundation program director who oversees funds for the two projects. "Each of these approaches could have a very significant impact on polymer manufacturing."

Plastics are polymers, long, potentially complex, molecule chains crafted from an array of smaller chemical units. Using FRP, chemical engineers can create the right plastic for a range of applications, such as a specific trim for a car door or soft foam for a pillow.

For some plastics, the building-block molecules do not easily link together. To surmount this problem, researchers from Carnegie Mellon University in Pittsburgh, Pa., devised a process called atom transfer radical polymerization (ATRP), which provides creative ways to coax the chemical subunits into chains. However, this method comes with certain costs, such as the need for a copper catalyst that can become unwanted waste.

Now, the Carnegie Mellon researchers have discovered that adding vitamin C, glucose, or other electron-absorbing agents to the ATRP process can reduce the amount of copper catalyst by a factor of 1000. Because the catalyst often needs to be removed from the end products, less copper means far less waste and drastically reduced removal costs. Mass manufacturing could become more affordable for a range of items such as advanced sensors, drug delivery systems, paint coatings, and video displays.

The research is described in a paper in the Oct. 17, 2006, issue of the Proceedings of the National Academy of Sciences.

At the University of Pennsylvania (UPenn), researchers are using a different approach to improve FRP. Called single electron transfer-living radical polymerization, the new method relies upon relatively low-energy reactions, uses elemental copper (copper metal, as opposed to copper in a chemical solution) as a catalyst to limit byproducts and allows manufacturers to use one of the most environmentally friendly solvents in the arsenal, water. The entirely new method of polymerization builds upon existing mechanisms to craft large molecules very quickly.


###
The UPenn researchers presented their findings in the online Journal of the American Chemical Society on Oct. 5, 2006.

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $5.58 billion. NSF funds reach all 50 states through grants to nearly 1,700 universities and institutions. Each year, NSF receives about 40,000 competitive requests for funding, and makes nearly 10,000 new funding awards. The NSF also awards over $400 million in professional and service contracts yearly.

Receive official NSF news electronically through the e-mail delivery and notification system, MyNSF (formerly the Custom News Service). To subscribe, visit http://www.nsf.gov/mynsf/ and fill in the information under "new users".

Useful NSF Web Sites:

NSF Home Page: http://www.nsf.gov
NSF News: http://www.nsf.gov/news/
For the News Media: http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics: http://www.nsf.gov/statistics/
Awards Searches: http://www.nsf.gov/awardsearch/
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PostPosted: Mon Apr 02, 2007 8:30 am    Post subject: Fat overrides effects of vitamin C Reply with quote

Society for Experimental Biology
1 April 2007

Fat overrides effects of vitamin C

Fats in our stomach may reduce the protective effects of antioxidants such as vitamin C. Scientists at the University of Glasgow found that in the presence of lipid the ability of antioxidants, such as ascorbic acid (the active component of vitamin C), to protect against the generation of potential cancer-forming compounds in the stomach is less than when no lipids are present. “Our results illustrate how diet can influence gastric biochemistry”, says Emilie Combet, the post-doctoral researcher working on the project, who will be presenting her results at the Society of Experimental Biology’s Annual Main Meeting on Monday 2nd of April.

The incidence of cancer of the proximal stomach has been increasing over the last 20 years for which environmental factors, such as diet, certainly play a part. Nitrite, which is present in our saliva and is derived from nitrate in our diet, is thought to be a pre-carcinogen for gastric cancer. When it is swallowed and enters the acidic environment of the stomach, nitrite spontaneously forms nitrosating species able to convert a range of targets, such as secondary amines and bile acids, into carcinogenic N-nitrosocompounds. Antioxidants such as ascorbic acid protect against the formation of these nitrosocompounds by converting the nitrosating species back into nitric oxide (NO). However, NO diffuses rapidly to lipids, where it reacts with oxygen to reform nitrosating species. The presence of lipids therefore overrides the protective effect of vitamin C against the formation of harmful compounds.

###
The research, funded by the World Cancer Research Fund, will investigate further the impact of dietary lipids on gastric biochemistry and the fate of nitrite, in relation to malignancies of the upper stomach.
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PostPosted: Sat Apr 28, 2007 7:24 am    Post subject: Scientists Find Missing Link to Understand How Plants Make V Reply with quote

Scientists Find Missing Link to Understand How Plants Make Vitamin C
27 April 2007
Darmouth Medical School

HANOVER, NH—Vitamin C is possibly the most important small molecule whose biosynthetic pathway remained a mystery. That is until now.

A group of UCLA and Dartmouth researchers, who normally work on genes involved in aging and cancer in animals, discovered the last piece of the puzzle, they report in a study published online April 26 in the Journal of Biological Chemistry.

Dr. Steven Clarke of the UCLA Molecular Biology Institute and the Department of Chemistry and Biochemistry explains, "We were working on an interesting gene in worms." One insight led to another until, "We uncovered the last unknown enzyme in the synthesis of vitamin C in plants," said Dr. Charles Brenner of Dartmouth Medical School's Norris Cotton Cancer Center and Department of Genetics.

For the full article:

http://dms.dartmouth.edu/news/.....nner.shtml
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PostPosted: Thu May 24, 2007 11:48 am    Post subject: Plants that produce more vitamin C may result from UCLA-Dart Reply with quote

University of California - Los Angeles
24 May 2007

Plants that produce more vitamin C may result from UCLA-Dartmouth discovery

UCLA and Dartmouth scientists have identified a crucial enzyme in plant vitamin C synthesis, which could lead to enhanced crops. The discovery now makes clear the entire 10-step process by which plants convert glucose into vitamin C, an important antioxidant in nature.

"If we can find ways to enhance the activity of this enzyme, it may be possible to engineer plants to make more vitamin C and produce better crops," said Steven Clarke, UCLA professor of chemistry and biochemistry, director of UCLA's Molecular Biology Institute and co-author of the research study, to be published as a 'Paper of the Week' in the Journal of Biological Chemistry and currently available online.

"We hit on gold," Clarke said, "because we now have a chance to improve human nutrition and to increase the resistance of plants to oxidative stress. Plants may grow better with more vitamin C, especially with more ozone in the atmosphere due to pollution."

Carole Linster, a UCLA postdoctoral fellow in chemistry and biochemistry and lead author of the study, discovered the controlling enzyme, GDP-L-galactose phosphorylase, which serves as the biosynthetic pathway by which plants manufacture vitamin C.

"Our finding leads to attractive approaches for increasing the vitamin C content in plants," Linster said. "We now have two strategies to provide enhanced protection against oxidative damage: Stimulate the endogenous activity of the identified enzyme or engineer transgenic plants which overexpress the gene that encodes the enzyme."

When life on Earth began, there was almost no oxygen, Clarke noted.

"Two billion years ago, plants devised an efficient way to get sunlight to make sugar from carbon dioxide that produced oxygen as a waste product; that waste product probably killed off most of all living species at that time," Clarke said. "The only organisms that survived developed defenses against it, and one of the best defenses is vitamin C. Plants learned how to make vitamin C to protect themselves."

Prior to the new research, vitamin C may have been the most important small molecule whose biosynthetic pathway remained a mystery.

An essential vitamin for humans, vitamin C is also an important antioxidant for animals and plants. Humans do not have the ability to make vitamin C and get it from dietary sources, especially from plants. It was not until 1998 that a biosynthetic pathway was proposed to explain how plants make this compound. Research confirmed much of the pathway, although one crucial missing link continued to baffle scientists and remained unknown until this new research.

Clarke, who studies the biochemistry of aging, said the finding is an example of serendipity in science.

The research started as an effort to understand the role of a gene in Caenorhabditis elegans, a tiny worm used as a model for aging studies by Tara Gomez, a former UCLA undergraduate in Clarke's laboratory and now a graduate student at the California Institute of Technology. The gene's sequence suggested that it was related to a family of genes altered in cancer, known as HIT genes; these genes are studied in the laboratory of Charles Brenner at the Norris Cotton Cancer Center at Dartmouth Medical School.

Collaboration between Clarke's and Brenner's laboratories revealed a similarity between the worm gene and the product of the VTC2 gene of Arabidopsis thaliana, a small roadside plant. Mutations in this gene had been previously linked to low levels of vitamin C. Linster and Gomez were able to express and to purify the plant VTC2 enzyme from bacteria. The research team, led by Linster, produced the GDP-L-galactose substrate and reconstituted in test tubes the mysterious seventh step in vitamin C synthesis.

Clarke and Brenner liken the first six steps in vitamin C synthesis to a roadmap in which there are multiple possible routes from glucose to a variety of cellular compounds. Once the GDP-L-galactose compound takes the exit marked "VTC2," however, the atoms are reconfigured to make vitamin C. The remaining three steps, like a curving driveway, "require some turns but no real choices and no backing up," Brenner said.

The researchers are still studying what VTC2-related genes do in animals and how these genes may relate to aging and cancer.


###
The research was federally funded by the National Institute on Aging, the National Institute of General Medical Sciences and the National Science Foundation, and by a fellowship Linster received from the government of Luxembourg.

The scientific team included UCLA researcher Lital Adler; Princeton undergraduate and former UCLA research assistant Brian D. Young; and Dartmouth researcher Kathryn Christensen.

About UCLA

UCLA is California's largest university, with an enrollment of nearly 37,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer more than 300 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Four alumni and five faculty have been awarded the Nobel Prize.
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PostPosted: Mon Sep 10, 2007 1:51 pm    Post subject: How vitamin C stops the big 'C' Reply with quote

Johns Hopkins Medical Institutions
10 September 2007

How vitamin C stops the big 'C'

Nearly 30 years after Nobel laureate Linus Pauling famously and controversially suggested that vitamin C supplements can prevent cancer, a team of Johns Hopkins scientists have shown that in mice at least, vitamin C - and potentially other antioxidants - can indeed inhibit the growth of some tumors ¯ just not in the manner suggested by years of investigation.

The conventional wisdom of how antioxidants such as vitamin C help prevent cancer growth is that they grab up volatile oxygen free radical molecules and prevent the damage they are known to do to our delicate DNA. The Hopkins study, led by Chi Dang, M.D., Ph.D., professor of medicine and oncology and Johns Hopkins Family Professor in Oncology Research, unexpectedly found that the antioxidants’ actual role may be to destabilize a tumor’s ability to grow under oxygen-starved conditions. Their work is detailed this week in Cancer Cell.

“The potential anticancer benefits of antioxidants have been the driving force for many clinical and preclinical studies,” says Dang. “By uncovering the mechanism behind antioxidants, we are now better suited to maximize their therapeutic use.”

“Once again, this work demonstrates the irreplaceable value of letting researchers follow their scientific noses wherever it leads them,” Dang adds.

The authors do caution that while vitamin C is still essential for good health, this study is preliminary and people should not rush out and buy bulk supplies of antioxidants as a means of cancer prevention.

The Johns Hopkins investigators discovered the surprise antioxidant mechanism while looking at mice implanted with either human lymphoma (a blood cancer) or human liver cancer cells. Both of these cancers produce high levels of free radicals that can be suppressed by feeding the mice supplements of antioxidants, either vitamin C or N-acetylcysteine (NAC).

However, when the Hopkins team examined cancer cells from cancer-implanted mice not fed the antioxidants, they noticed the absence of any significant DNA damage. “Clearly, if DNA damage was not in play as a cause of the cancer, then whatever the antioxidants were doing to help was also not related to DNA damage,” says Ping Gao, Ph.D, lead author of the paper.

That conclusion led Gao and Dang to suspect that some other mechanism was involved, such as a protein known to be dependent on free radicals called HIF-1 (hypoxia-induced factor), which was discovered over a decade ago by Hopkins researcher and co-author Gregg Semenza, M.D., Ph.D., director of the Program in Vascular Cell Engineering. Indeed, they found that while this protein was abundant in untreated cancer cells taken from the mice, it disappeared in vitamin C-treated cells taken from similar animals.

“When a cell lacks oxygen, HIF-1 helps it compensate,” explains Dang. “HIF-1 helps an oxygen-starved cell convert sugar to energy without using oxygen and also initiates the construction of new blood vessels to bring in a fresh oxygen supply.”

Some rapidly growing tumors consume enough energy to easily suck out the available oxygen in their vicinity, making HIF-1 absolutely critical for their continued survival. But HIF-1 can only operate if it has a supply of free radicals. Antioxidants remove these free radicals and stop HIF-1, and the tumor, in its tracks.

The authors confirmed the importance of this “hypoxia protein” by creating cancer cells with a genetic variant of HIF-1 that did not require free radicals to be stable. In these cells, antioxidants no longer had any cancer-fighting power.


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The research was funded by the National Institutes of Health.

Authors on the paper are Dean Felsher of Stanford; and Gao, Huafeng Zhang, Ramani Dinavahi, Feng Li, Yan Xiang, Venu Raman, Zaver Bhujwalla, Linzhao Cheng, Jonathan Pevsner, Linda Lee, Gregg Semenza and Dang of Johns Hopkins.

On the Web:

http://www.hopkinsmedicine.org...../dang.html
http://www.hopkins-ice.org/vas.....menza.html
http://www.cancercell.org/
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PostPosted: Mon Sep 24, 2007 12:57 pm    Post subject: Study shows vitamin C is essential for plant growth Reply with quote

University of Exeter
23 September 2007

Study shows vitamin C is essential for plant growth

Scientists from the University of Exeter and Shimane University in Japan have proved for the first time that vitamin C is essential for plant growth. This discovery could have implications for agriculture and for the production of vitamin C dietary supplements.

The study, which is now published online in The Plant Journal, describes the newly-identified enzyme, GDP-L-galactose phosphorylase, which produces vitamin C, or ascorbate, in plants. Vitamin C is already known to be an antioxidant, which helps plants deal with stresses from drought to ozone and UV radiation, but until now it was not known that plants could not grow without it.

Professor Nicholas Smirnoff of the University of Exeter, lead author on the paper said: ‘Vitamin C is the most abundant antioxidant in plants and yet its functions are poorly understood. By discovering that the new enzyme is encoded by two genes, we were able to engineer vitamin C-free plants and found that they were unable to grow.’

The discovery also identifies the new enzyme as a key player in controlling vitamin C accumulation in response to light. Vitamin C provides protection against the harmful side-effects of light during photosynthesis, the process by which light energy is used to convert carbon dioxide into plant matter.

Professor Nicholas Smirnoff continued: ‘The discovery is exciting for me because it is the culmination of a long-term research programme on vitamin C in plants at the University of Exeter. It opens new opportunities to understand fundamental growth processes in plants and to improve plant resistance to stresses in a changing climate. In the longer term I hope that it will contribute to the efforts of plant scientists to improve crop yield in a sustainable manner.’

The findings could also pave the way for a new approach to producing vitamin C dietary supplements. In Britain we spend an estimated £20 million on vitamin C tablets each year, making this the most widely-used dietary supplement. Vitamin C is currently produced by mixed fermentation and chemical synthesis. The new enzyme provides the potential to engineer microbes to produce vitamin C by a simpler one-step process.


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This research was funded by Bio-Technical Resources, Exeter University School of Biosciences, the Japan Society for the Promotion of Science and a Biotechnology and Biological Sciences Research Council (BBSRC) studentship.
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