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.
Zinc: The impact of zinc is
similar in nature to iron but the relationship is not as strong. Along with iron
and calcium, zinc competes with lead for absorption inside the gut, but zinc
does not seem to be as effective in displacing lead, though consumption with the
amino acid lysine can help. The evidence for zinc supplementation having an
effect on blood lead appears weak, with a very large double blind study finding
no impact, though a number of studies have found impacts in conjunction with
other nutrients or chelators. One study on rats (Tandon 2000) claimed “the use
of becozinc (a pharmacological preparation containing vitamins of the B-complex
group, vitamin C, and zinc) as a safe alternate to treatment of lead poisoning
with chelating agents,” finding becozinc produced higher excretion than
vitamin C or thiamin alone.
Animal studies indicate that
zinc may reduce lead damage to some brain functions, probably because zinc
concentrations are particularly high in the brain. Its impact is this regard,
however, may be less than that of calcium. Animal studies also show dietary zinc
reduces lead uptake and toxicity in the kidney, liver and testes but may worsen
lead’s impact on the thyroid gland and its functions, potentially impacting on
bone resorption. It may also decrease the depletion of calcium and magnesium in
organs by lead and alcohol. Zinc deficiency increases bone resorption that can
lead to higher blood lead levels. Supplementary zinc reduces lead accumulation
in the bones of rats but can also reduce bone density (increasing the risk of
osteoporosis). Prolonged high levels of zinc supplementation (above 29mg a day)
can block copper absorption, leading to sideroblastic anaemia (inability to
incorporate iron in haemoglobin) and iron toxicity as copper is essential to
iron absorption and transfer within the body.
Zinc: is found in a variety
of food. Rear row: pecan nuts, sesame seeds, cashews, dates,
linseed, wheat germ. Middle row: cocoa, oysters, crab, poppy
seeds, beef. Front Row: blue cheese, eggs, pine seeds
Zinc is found in significant
quantities in oysters, wheat germ, cocoa, crab, seeds (poppy, sesame, linseeds,
alfalfa), nuts (pine, cashew, pecan), beef, dates, eggs and blue cheese. Zinc is
strongly inhibited by phytates, (found in nuts, seeds and whole grains), with
zinc absorption being reduced by up to 67% when consumed with high phytate food.
Folic acid is also is a significant inhibitor. The UK Expert Group on Vitamins
and Minerals recommends no more than 25mg of zinc should be taken as a
supplement and that total daily intake should not exceed 42mg a day. If you are
seeking to maximize your iron levels, zinc supplements totalling more than 15mg
should not be consumed within 2-3 hours of iron rich meals or iron supplements.
Zinc can also interfere with magnesium absorption but this probably only has
significance with very high levels of supplementation.
Iron and/or Zinc
Supplementation Did Not Reduce Blood Lead Concentrations in Children in a
Randomized, Placebo-Controlled Trial Jorge L. Rosado, Patricia Lo´ pez,
Katarzyna Kordas, G. Garcı´a-Vargas, D. Ronquillo, J. Alatorre, and R. J.
Stoltzfus J. Nutr. 2006 136: 2378-2383. http://jn.nutrition.org/cgi/content/full/136/9/2378
[A large double blind study that found no impact on blood lead levels from daily
supplementation with 30 mg a day of iron and/or zinc.]
Selection of Nutrients for
Prevention or Amelioration of Lead-Induced Learning and Memory Impairment in
Rats Guangqin Fan, Chang Feng, Yu Li, C Wang, J Yan, W Li, J Feng, X Shi and Y
Bi Annals of Occup Hygiene 2009 53(4):341-351 http://annhyg.oxfordjournals.org/cgi/content/abstract/53/4/341
[Shows that zinc may help protect against lead damage to some memory and
learning functions, at least in rats. It found, however, that no single nutrient
alone played an adequate role in protecting brain function, and that zinc worked
most effectively with Vitamin C and glycine]
Therapeutic Influence of Zinc
and Ascorbic Acid Against Lead-induced Biochemical Alterations Anil Kumar
Upadhyay, Ramesh Mathur, Monika Bhadauria and Satendra Kumar Nirala Thérapie
2009 Novembre-Décembre; 64 (6): 383-388 www.journal-therapie.org/index.php?option=article&access=doi&doi=10.2515/
therapie/2009055
[Further research demonstrating the importance of combining vitamin C
with zinc to protect against lead-induced brain damage].
Calcium or zinc
supplementation reduces lead toxicity: assessment of behavioral dysfunction in
young and adult mice Rantham P.J. Prasanthi, Gadi H. Reddy, Gottipolu R. Reddy
Nutritional Research Volume 26, Issue 10, Pages 537-545 (October 2006) http://dx.doi.org/10.1016/j.nutres.2006.09.004 [Finds that
zinc has a significant effect on lead-impaired neural related performance,
though less than calcium.]
Role of vitamins in treatment
of lead intoxication Sushil K. Tandon, Surendra Singh, The Journal of Trace
Elements in Experimental Medicine, Vol 13 No 3, Pages 305 – 315, (2000) www3.interscience.wiley.com/journal/72510361/abstract?CRETRY=1&SRETRY=0
[Finds that Benozinc, a compound containing vitamin B complex, vitamin C and
zinc reduced blood lead levels more than vitamin C or thiamin in rats]
Study on the influence of
L-lysine and zinc administration during exposure to lead and ethanol in rats
Maria Chichovska and Anguel Anguelov Vet. arhiv 76, 65-73, 2006. http://hrcak.srce.hr/5086
[Finds that zinc and lysine (an amino acid) reduce uptake of lead to organs,
particularly the brain and reduce alcohol’s exacerbating effect on lead
toxicity.]
Effects of Zinc
Coadministration on Lead Toxicities in Rats Fengyuan Piao, Fanyin Cheng, Haibo
Chen, Gang Li, Xiance Sun, Shang Lui, Toru Yamauchi and Kazuhito Yokoyama
Industrial Health 2007, 45, 546-551 www.jstage.jst.go.jp/article/indhealth/45/4/546/_pdf
[Finds that zinc reduces the impact of lead on the testes but increases its
impact on the vital thyroid gland]
Marginal Zinc Deficiency
Exacerbates Bone Lead Accumulation and High Dietary Zinc Attenuates Lead
Accumulation at the Expense of Bone Density in Growing Rats Jennifer A.
Jamieson, Carla G. Taylor, and Hope A. Weiler Toxicological Sciences 92(1),
286–294 (2006) http://toxsci.oxfordjournals.org/cgi/reprint/92/1/286
[Found that high zinc levels decrease both bone lead levels and bone density
while zinc deficiency increases bone lead levels but not lead toxicity]
Interaction of lead with some
essential trace metals in the blood of anemic children from Lucknow, India M.
Ahameda, S. Singha, J.R. Beharib, A. Kumarc and M.K.J. Siddiquia Clinica Chimica
Acta Volume 377, Issues 1-2, 2 February 2007, Pages 92-97 http://dx.doi.org/10.1016/j.cca.2006.08.032 [Found that
children with lead-induced anemia are likely to have lower zinc levels]
Element of caution: a case of
reversible cytopenias associated with excessive zinc supplementation Julie A.
Irving, Andre Mattman, Gillian Lockitch, Kevin Farrell and Louis D. Wadsworth
CMAJ July 22, 2003; 169 (2) www.cmaj.ca/cgi/content/full/169/2/129 [demonstrates the
ability of zinc supplementation to block copper absorption]