LEAD
Action News vol 10 no 2, June 2010, ISSN 1324-6011
Incorporating Lead Aware Times ( ISSN 1440-4966) and Lead Advisory Service
News (ISSN 1440-0561)
The Journal of The LEAD (Lead Education and Abatement Design) Group Inc.
Vitamin C
Low levels of Vitamin C [ascorbic acid] are strongly linked to high lead
levels. Individuals who consume more than 340 mg of vitamin C tend to have
lower blood lead levels than those who consume less than 110 mg.
Consumption of 1000 mg a day has been shown to significantly decrease lead
levels in some, though not all, cases - apparently more through reduced
absorption rather than increased excretion. Vitamin C has been
consistently shown to protect the concentration of molecules such as ALAD
that are associated with red blood cell manufacture. Vitamin C improves
iron absorption if it can mix with food in the stomach (food or liquid
being preferable forms), as well as increasing iron’s capacity to
displace lead during food absorption. There is some evidence that Vitamin
C can inhibit lead uptake at a cellular level as well as lead’s
cytotoxicity (cellular toxicity). In combination with zinc, glycine and
vitamin E, it has been found effective in partially protecting a range of
body organs, particularly the brain and liver, from lead-induced damage in
animal experiments (see zinc, glycine and vitamin E entries in this
paper). Rat experiments have demonstrated reduced lead impacts on a
variety of body organs, even when administered alone. Vitamin C has been
used as a chelator (metal remover) in a variety of naturopathic lead
treatments, but experimental results on its ability to increase lead
excretion contain significant inconsistencies. Similarly, while some
studies have linked reduced hypertension to Vitamin C levels, this has not
been confirmed in long-term human studies. Vitamin C is non-toxic, and no
significant drawbacks for healthy young adults have been documented at
daily intakes below 1000mg.
However, this should not
be seen as an endorsement of megadoses of vitamin C, defined for this
paper as consumption >2000mg per day (the recommended daily upper limit
in the USA set by the Food and Nutrition Board for healthy adults), since,
like other nutrients vitamin C has a range of consequences on essential
nutrients (definitely increasing iron absorption while possibly reducing
copper levels, which enable iron transport within the body) and body
systems (including possible increased risk of cataract or kidney stone
formation for some individuals at supplementation levels of around
1,000mg). Supplements of any type should only be taken with medical
advice, particularly if medication is being consumed.
The fact that a plateau
exists beyond which excess dietary or supplementary Vitamin C has little
impact, while intravenously administered Vitamin C can result in serum
(blood) vitamin C levels over six times higher, suggests there may be
drawbacks to high levels of vitamin C, though few examples have as yet
been well documented. Oral consumption of more than 500 mg at a time will
not generally increase serum vitamin C above 500mg supplementation levels
for more than a few hours, due to increased excretion and breakdown,
though vitamin C proponents argue that various organs such as the retina
of the eye, or the brain, can retain much higher levels (up to 100 times
greater) than the blood. Maximizing serum (blood) Vitamin C concentrations
requires new doses every four hours. There is some evidence from animal
studies that extreme vitamin C intake can negate the benefits of vitamin C
supplementation as a treatment for lead damage, as under certain
circumstances ascorbic acid can act as an oxidizing agent rather than as
an antioxidant.
For healthy young
non-smoking adult individuals, 400 mg a day, a minimum recommended by the
Linus Pauling Institute, seems both a reasonable and safe dietary goal,
though this may not be adequate for all sectors of the population as
vitamin C absorption may decline with age, or may be impacted by smoking,
diet (including alcohol) or medication. High levels of vitamin C reduce
the risk of Helicobacter pylori infections that can reduce stomach
acidity, in turn reducing iron, zinc, copper, calcium and B12 absorption.
Vitamin C: 480 g of the foods (pictured above) eaten raw should provide sufficient Vitamin C to reach 400 mg a day (much more if cooked, for juice equivalent check labels). Top row: parsley, guava (juice pictured), blackcurrant (juice pictured), kale Middle Row: radish, capsicum (bell pepper in US), kiwi fruits, broccoli Bottom row: feijoa, baby capsicums, brussel sprouts, guava, horse radish Not pictured: Mustard greens, red peppers, thyme
Vitamin C
is found in a wide range of fruits and vegetables. Cooking reduces vitamin
C content, but the degree varies widely between foods (potatoes lose
20-30% from boiling, broccoli 50-60%) and cooking styles (steaming is
generally the best, baking the worst) and its significance depends on the
foods’ initial content (boiled broccoli can still have more vitamin C
than an orange). Vitamin C will continue to be lost if material is left in
a warming trays, as a major loss is from enzymes produced by cooking whose
activity continues in warm temperatures.
Vitamin C Jane Higdon
The Linus Pauling Institute http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/
[A good overview of vitamin C as a nutrient with a short section on
lead toxicity. Recommends 400 mg a day as a minimum intake. Supports
caution for individuals who may be at risk of kidney stones, noting
that studies are contradictory]
Lead toxicity Part
II: the role of free radical damage and the use of antioxidants in the
pathology and treatment of lead toxicity Patrick, Lyn
Alternative Medicine Review Vol 10, No 4 Dec 2005 http://www.altmedrev.com/publications/11/2/114.pdf
[Contains a good summary of research into Vitamin C and lead levels.
Fig 4 is a graph of one study’s findings, charting serum [blood]
(rather than dietary) vitamin C and lead levels. Also quotes a study
where 1000mg a day of vitamin C had no effect on serum lead levels]
Relation of Nutrition
to Bone Lead and Blood Lead Levels in Middle-aged to Elderly Men - The
Normative Aging Study Yawen Cheng, Walter C. Willett, Joel Schwartz,
David Sparrow, Scott Weiss, and Howard H American Journal of
Epidemiology Vol. 147, No. 12 http://aje.oxfordjournals.org/content/147/12/1162.abstract
[Finds that individuals who consume over 340mg of vitamin C have
significantly lower blood lead levels than those who consume under 110
mg]
Relationship Of
Ascorbic Acid To Blood Lead Levels Simon, Joel A; Hudes, Esther S
JAMA, Vol. 281 No 24 pp 2289 – 2293 http://jama.jamanetwork.com/article.aspx?articleid=190540
[Shows that adults with high levels of Vitamin C have approximately
one third the risk of high lead levels, while the correlation with
children over 6 years of age is even stronger.]
Testing of chelating
agents and vitamins against lead toxicity using mammalian cell
cultures Anna B. Fischer, Cristine Hess, Tilo Neubauer and Thomas
Eikmann Analyst, January 1998, Vol. 123 (55-58) http://pubs.rsc.org/en/Content/ArticleLanding/1998/AN/a705518h#!divAbstract
[Finds that in cell
cultures Vitamin C inhibits lead uptake on a cellular level and
reduces cytotoxicity]
The Effect of
Ascorbic Acid Supplementation on the
Blood Lead Levels of Smokers Earl B. Dawson,
Douglas R. Evans, William A. Harris, MC Teter, WJ McGanity J Am
College of Nutr, Vol. 18, No. 2, 166–170 (1999) http://www.comilac.com.tr/uploads/pdf/23PomGT.pdf
[Found that a supplement of 1000mg reduced blood lead levels while
200mg had no effect, even though there was no increase in lead
excretion. Note that smoking reduces serum Vitamin C levels so
supplementation required should be lower for non-smokers. Mentions
previous research on Vitamin C’s capacity to improve iron uptake
relative to lead.]
Antioxidant effects
of α tocopherol, ascorbic acid and l.-methionine on lead-induced
oxidative stress to the liver, kidney and brain in rats R. C. Patra,
D. Swarup and S. K. Dwivedi Toxicology Vol 162, No 2, 11 May 2001,
Pages 81-88 http://www.sciencedirect.com/science/article/pii/S0300483X01003456
[Found that vitamin C
reduced lead impacts on these organs without reducing blood and tissue
lead levels, even raising lead levels in the kidneys]
Influence of vitamin
C supplementation on lead-induced histopathological alterations in
male rats Mahmoud Shaban El-Neweshy and Mahmoud Shaban and Yasser Said
El-Sayed Experimental and Toxicologic Pathology Article in Press,
Corrected Proof online 6 January 2010 http://www.sciencedirect.com/science/article/pii/S094029930900298X
[A very recent piece of animal research demonstrating the
capacity of vitamin C to reduce lead impacts on a variety of body
organs.]
Effect of Ascorbic
Acid and Thiamine Supplementation at Different Concentrations on Lead
Toxicity in Liver Chunhong Wang, Jiancheng Liang, Chunlian Zhang, Y
Bi, X Shi And Q Shi Ann. Occup. Hyg., Vol. 51, No. 6, pp. 563–569,
2007 http://annhyg.oxfordjournals.org/content/51/6/563.full.pdf
[Found that in mice, while the vitamins mentioned significantly
reduced lead-induced liver damage they had no effect at all at the
highest vitamin C dose.]
Vitamin C
pharmacokinetics in healthy volunteers: Evidence for a recommended
dietary allowance Mark Levine, Cathy Conry-Cantilenat, Yaohui Wang,
Richard W. Welch, Philip W. Washko, Kuldeep R. Dhariwal, Jae B. Park,
Alexander Lazarev, James F. Graumlich, Jean Kings, And Louis R.
Cantilena Proc. Natl. Acad. Sci. USA Vol. 93, pp. 3704-3709, April
1996 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC39676/pdf/pnas01515-0554.pdf
[Finds that supplemental doses above 200mg tend to be excreted within
24 hours and that little prolonged increase in serum Vitamin C is
achieved above 400mg per day.]
Criteria and
Recommendations for Vitamin C Intake Mark Levine; Steven C. Rumsey;
Rushad Daruwala; Jae B. Park: Yaohui Wang. JAMA.
1999;281(15):1415-1423 http://jama.jamanetwork.com/article.aspx?articleid=189543
[indicates doses of more than 500mg have little impact on serum
vitamin C levels and recommends caution for doses of 1000 mg a day or
higher.]
Vitamin C
Pharmacokinetics: Implications for Oral and Intravenous Use Sebastian
J. Padayatty; He Sun,; Yaohui Wang, ; Hugh D. Riordan; Stephen M.
Hewitt; Arie Katz; Robert A. Wesley; and Mark Levine Annals of
Internal Medicine Vol 140 No 7 533-528 http://annals.org/article.aspx?articleid=717329
[Notes the much higher levels of serum vitamin C that can be achieved
through intravenous injection. Figure 2, p 536 clearly indicates that
maximizing serum [blood] vitamin C levels by oral supplementation
requires new doses about every 4 hours.]
Vitamin C
Requirements: Optimal Health Benefits Vs Overdose Ronald Roth Acu-Cell
www.acu-cell.com/vitc.html [A cautionary exploration of the
wider impacts of Vitamin C supplementation]
Correlation Between
Helicobacter pylori Infection and Vitamin C Levels in Whole Blood,
Plasma, and Gastric Juice, and the pH of Gastric Juice in Korean
Children Park, Jae H.; Kim, Su Y.; Kim, Dong W.; Lee, Woo G.; Rhee,
Kwang H.; Youn, Hee S J. of Pediatric Gastroenterology and Nutrition:
July 2003 Vol 37 Is 1
p53-62 http://journals.lww.com/jpgn/Abstract/2003/07000/Correlation_Between_Helicobacter_pylori_Infection.9.aspx
[Indicates that
individuals with higher vitamin C levels have lower rates of H. pylori
infection and less severe infections]
Vitamin C supplements
and the risk of age-related cataract: a population-based prospective
cohort study in women Susanne Rautiainen, Birgitta Ejdervik Lindblad,
Ralf Morgenstern and Alicja Wolk Am J Clin Nutr 2010; Vol. 91, No. 2,
487-493, Feb 2010. http://ajcn.nutrition.org/content/91/2/487.abstract
[Finds a higher risk of cataracts among older women taking vitamin C
supplements estimated to average 1000mg per day particularly if using
HRT (Hormone Replacement Therapy) or corticosteroids
(anti-inflammatory agents found in arthritis and asthma medication as
well as several others)]
Lack of Long-Term
Effect of Vitamin C Supplementation on Blood Pressure Mi Kyung Kim;
Satoshi Sasaki; Shizuka Sasazuki; Shunji Okubo; Masato Hayashi;
Shoichiro Tsugane Hypertension. 2002;40:797-803 http://hyper.ahajournals.org/content/40/6/797.full
[A large five year study that found no link between hypertension and
vitamin C supplementation or serum vitamin C levels]
Why are Whole Food
Dietary Supplements Better than Single Nutrient Supplements? A Review
Based on the Vitamin C Literature Jane Ramberg; Lam Le; Shayne
McAnalley; C. Michael Koepke; Eileen Vennum, and Bill McAnalley Mens-Women
Health http://devoutventures.com/files/WholeFoodSupplements.ppt
[a good outline of why it is better to obtain Vitamin C from food (or
mixed with foods) rather than as a separate supplement. Notes that
citrus fruit (oranges, lemons etc) have more of an impact on serum
vitamin C levels than their vitamin C content suggests.]