Hello.
Vitamin C has been shown to be important for good health.
According to the Mayo Clinic web site, the current Recommended Daily
Allowance (RDA) for vitamin C is 90mg per day for adult males. More
from the Mayo Clinic:
"What it does: Vitamin C is a water-soluble vitamin that maintains
skin integrity, helps heal wounds and is important in immune
functions. It also has antioxidant properties, helping to prevent cell
damage by neutralizing 'free radicals' — molecules believed to be
associated with aging and certain diseases."
"What the research says: Studies have shown that people who eat foods
high in vitamin C have lower rates of cancer and heart disease, though
it's unclear whether taking vitamin C supplements produces similar
benefits...
The Institute of Medicine states that there are no established
benefits for consuming vitamin C in doses higher than the RDA. Other
research has suggested that 200 mg/day is the optimal dose."
"Cautions: See your doctor before taking vitamin C if you have gout,
kidney stones, sickle cell anemia or iron storage disease. If you're
pregnant or breast-feeding, don't take vitamin C in doses greater than
the RDA for pregnant or breast-feeding women."
Source: Mayo Clinic
http://www.mayoclinic.com/invoke.cfm?id=SA00013
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Other research indicates that vitamin C has many health benefits.
From the VITAMIN C: A SCIENTIFIC REVIEW THE NATIONAL RESEARCH COUNCIL
FOR HEALTH (NRCH) [ http://ce.rexallsundown.com/pages/booklets/vitaminC.aspx
] , here are some of the claimed health benefits of vitamin C:
* Fewer and less colds
"In some, but not all cases, supplementation with vitamin C resulted
in fewer colds. However, in supplemented patients, the colds lasted
for fewer days, and the symptoms were milder. Not all of the results
were statistically significant, but all of them pointed consistently
in the same direction."
* Reduced asthma symptoms
"studies of vitamin C and pulmonary function have shown that vitamin C
decreases bronchoconstriction and may have other beneficial effects in
asthmatics."
* Reduced blood pressure
"Studies in several parts of the world, including the United States,
Japan, and Finland, have indicated that people with better vitamin C
nutriture have lower blood pressures."
* Reduced risk for coronary heart disease
"vitamin C deficiency may be a risk factor for coronary heart disease.
"
* Stronger bones
"Because vitamin C is necessary for the normal synthesis of collagen,
it is important to bone health. However, increased production of
collagen can lead to increased bone formation only if sufficient
calcium is present to mineralize the collagen matrix. Therefore,
vitamin C would be expected to enhance bone formation only in the
presence of adequate calcium intake."
* Reduced risk of cataracts
"Epidemiological studies in several countries have associated higher
intakes or blood levels of vitamin C with reduced risk of cataracts.
The use of vitamin C supplements or multivitamin supplements has also
been associated with a decrease in cataract risk."
* Better sperm quality
"Adequate amounts of vitamin C are needed for the normal production of
sperm. Studies in human subjects have shown that low- blood vitamin C
levels are associated with reduced sperm count and poor sperm quality.
Vitamin C supplementation leads to progressive improvement in sperm
characteristics"
Note, though, that the strength and evidence for these various health
claims is subject to debate. Many studies indicate mixed results. For
more inforamtion, view the whole report, VITAMIN C: A SCIENTIFIC
REVIEW THE NATIONAL RESEARCH COUNCIL FOR HEALTH (NRCH), courtesy of
rexallsundown.com
http://ce.rexallsundown.com/pages/booklets/vitaminC.aspx
--------
Research done for the National Institute of Health by Mark Levine MD
indicates that about 200mg per is an adequate level of Vitamin C,
while levels of 500mg or more may be excessive. 1000mg daily doses may
raise the risk of kidney stones, according to Levine.
From an NIH press release:
"Levine says adults need about 200 mg of vitamin C daily,
approximately the amount contained in five servings of fruits and
vegetables a day. 'Our work reinforces the health message that healthy
people should be eating five servings of a variety of fruits and
vegetables every day. You'll get adequate vitamin C and you have the
potential benefit of preventing disease, especially certain cancers,;
Levine explains. Scientists do not know if the protection comes from
vitamin C alone or from an interaction of vitamin C with other
substances in foods. The U.S. Department of Agriculture and the
National Cancer Institute both advocate a diet rich in fruits and
vegetables.
Healthy people are better off eating fruits and vegetables rather than
relying on supplements because absorption of the vitamin in
supplements varies widely, depending on manufacturing methods and the
dose taken. Daily doses of 200 mg of vitamin C from supplements do not
decrease the incidence of certain kinds of cancer.
The current Recommended Daily Allowance (RDA) for vitamin C is 60
mg/day, a number originally set in 1980 and reviewed in 1989 by the
Food and Nutrition Board, a part of the National Academy of Sciences.
The RDA is based on the amount of vitamin C needed to prevent scurvy,
a potentially fatal disease marked by fatigue and bleeding. 'We need
to think not just about deficiency, which has been the starting point
for recommended daily allowances,' Levine says, 'but about a variety
of other scientific factors, such as how much vitamin C is
concentrated in blood and tissue when a person takes a specific
amount, how much is excreted in urine, what the beneficial and adverse
effects are.'
When the subjects in Levine's study received 30 mg, most reported
feeling tired and irritable. At 200 mg, blood plasma had more than 80
percent maximal concentration of vitamin C and tissues were completely
saturated. At doses of 500 mg and higher, there was excess vitamin C
that was completely excreted in urine. At 1,000 mg, some volunteers
showed high levels of oxalate and uric acid in their urine, which
might lead to kidney stones."
Source: NIH press release
http://www.nih.gov/news/pr/apr99/niddk-20.htm
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Oregon State University's Linus Pauling Institute advocates high
doses of Vitamin C and disagrees with doctors such as Levine who
advocate 200mg limits.
See: "The Optimal Intake of Vitamin C"
http://lpi.oregonstate.edu/sp-su97/intake.html
"What About Vitamin C and Kidney Stones?"
http://lpi.oregonstate.edu/f-w99/kidneystones.html
--------
Also see:
"Can Vitamin C Shorten a Cold?" from WebMd.com:
http://my.webmd.com/content/article/50/40544.htm
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On the issue of Ester-C... Some research indicates that it may be
more easily absorbed than regular vitamin C.
From the article "What You Don't Know About Vitamin C":
"Ester-C is a mixture of several forms of vitamin C, such as calcium
ascorbate, ascorbate dehydroascorbate (the form that vitamin C assumes
to enter cells), various metabolites of vitamin C, such as aldonic
acids, calcium carbonate, water, and a bit of lecithin."
"Ester-C was initially reported in scientific literature when Anthony
J. Verlangieri, Ph.D., of the University of Mississippi, discussed the
substance in the Journal of Research Communications in Chemical
Pathology in 1987."
"This form of calcium ascorbate has less ionic character, is more
fat-soluble, and passes the mucosal barriers more rapidly than other
forms of vitamin C. The body circulates the nutrient longer, even
though Ester-C entered the bloodstream about twice as fast and put
more vitamin C in the blood than regular vitamin C. Dr. Verlangieri
said that it took 208 minutes before Ester-C was detected in urine,
contrasted with 104 minutes for ascorbic acid."
For more information visit Prohealthnetwork.com:
http://www.prohealthnetwork.com/library/showarticle.cfm/id/273/T/Both/
On the other hand, a group called the Vitamin C foundation recommends
plain vitamin C (ascorbic acid) instead of Ester-C because they
believe that mineral ascorbates like Ester-C "are generally not as
effective therapeutically as ascorbic acid."
See "Why the Foundation Does Not Recommend Ester-C"
http://www.vitamincfoundation.org/esterc.htm
To sum up, vitamin C is very important and beneficial. 100-200mg per
day from food (and possibly supplements) would certainly seem like a
good idea.
I hope this helps. If any part of my research is unclear, please use
the "request clarification" feature. Thanks. |
