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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)
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  Research article

Nutrition to Fight Lead Poisoning

By Robert J. Taylor, additional references sourced by Elizabeth O’Brien, Edited by Anne Roberts,
Photos by Catherine Sweeny. A Fact Sheet version of this Research Article can be found at www.lead.org.au/fs/Fact_sheet-Nutrients_that_reduce_lead_poisoning_June_2010.pdf

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.

Figure 7.1: Plasma vitamin C concentrations achieve steady state at intakes in excess of 200 mg/day. [Source: Levine M et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a Recommended Dietary Allowance. Proceedings of the National Academy of Sciences, 1996, 93:3704–3709.©The National Academy of Sciences 1996] Downloaded from www.pnas.org/content/93/8/3704.full.pdf+html [Accessed 25th January 2010]

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: 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.

  1. 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]
  2. 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 www.thorne.com/altmedrev/.fulltext/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]
  3. 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 www.aje.oxfordjournals.org/cgi/content/abstract/147/12/1162 [Finds that individuals who consume over 340mg of vitamin C have significantly lower blood lead levels than those who consume under 110 mg]
  4. Relationship Of Ascorbic Acid To Blood Lead Levels Simon, Joel A; Hudes, Esther S JAMA, Vol. 281 No 24 pp 2289 – 2293 http://jama.ama-assn.org/cgi/content/full/281/24/2289 [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.]
  5. 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) www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree
    .cfm?doi=a705518h&JournalCode=AN
    [Finds that in cell cultures Vitamin C inhibits lead uptake on a cellular level and reduces cytotoxicity]
  6. 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) www.jacn.org/cgi/reprint/18/2/166.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.]
  7. 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 www.ncbi.nlm.nih.gov/pubmed/11337108 [Found that vitamin C reduced lead impacts on these organs without reducing blood and tissue lead levels, even raising lead levels in the kidneys]
  8. 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://dx.doi.org/10.1016/j.etp.2009.12.003  [A very recent piece of animal research demonstrating the capacity of vitamin C to reduce lead impacts on a variety of body organs.]
  9. 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/cgi/reprint/51/6/563 [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.]
  10. 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 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.]
  11. 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.ama-assn.org/cgi/content/full/281/15/1415  [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.]
  12. 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 www.annals.org/cgi/content/abstract/140/7/533 [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.]
  13. 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]
  14. 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]
  15. 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. www.ajcn.org/cgi/content/abstract/91/2/487 [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)]
  16. 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/cgi/content/full/40/6/797 [A large five year study that found no link between hypertension and vitamin C supplementation or serum vitamin C levels]
  17. 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 www.mens-womens-health.com/supplements.html [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.]
  18. Top 10 Foods Highest in Vitamin C HealthAliciousNess www.healthaliciousness.com/articles/vitamin-C.php [a useful list of the richest common sources of vitamin C]

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