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

Iron is a key nutrient. It is part of the oxygen- bearing component of red blood cells (haemoglobin), and the prevention of haemoglobin formation by the presence of lead is the primary cause of lead-induced anaemia (hypochromic anaemia). Hypochromic anemia is produced by significant iron deficiency even if no lead is present. Iron also plays a significant role in brain activity and a wide range of other bodily functions.

Iron competes with lead for absorption in the gut and uptake within the body, and vitamin C can enhance its ability to displace lead. It has been linked to blood and organ lead levels and may protect the blood/brain barrier from lead impacts as well as reducing lead induced apoptosis (cellular suicide) within the brain. Individuals who are severely iron deficient can absorb up to 7 times more lead, as the body responds to iron deficiency by dispatching increasing amounts of the iron transporter DMT1 into the gut. Unfortunately DMT1 can carry eight metals including lead and will transport lead if insufficient iron is available. Unlike calcium, iron has a stronger affinity for its binding sites than lead, so is unlikely to be displaced by lead if iron levels are adequate; so there is considerable doubt whether iron supplementation has much impact within the body if adults are iron replete (with sufficient iron in storage, generally around 1000mg: the average amount stored by a western male omnivore), as the body stores excess iron or reduces absorption, with iron stores having considerably more impact than dietary content or iron bioavailability on iron absorption.

Iron deficiency is one of the most common nutrient deficiencies. Pre-menopausal women, pregnant women and infants are at higher risk of iron deficiency. Iron deficiency, particularly in children, has independent impacts on the brain that can exacerbate lead impacts.

Iron itself is toxic and high iron levels have a range of negative effects although it is much rarer than iron deficiency, particularly among pre-menopausal women, pregnant women, infants and vegetarians. A US organization offering free testing on the east coast of the USA has found there are five individuals who have low iron levels, for every one individual with high iron levels. Infants and young children are unable to reduce absorption when high amounts of iron are ingested, so are highly susceptible to iron poisoning. Consumption of adult iron supplements has been the most common form of infant poisoning in the USA.

Meat consumption (particularly red meat), cooking acidic vegetables in non enamelled cast iron pots, significant dietary vitamin C consumption with meals (100 mg producing maximum impact) and limited alcohol consumption (2 glasses per day) can reduce the risk of iron deficiency. Unfermented soy products, phytates (in whole grains, bran, nuts or seeds), some polyphenols (notably those in tea and coffee), egg whites and large quantities of calcium rich products (more than 1 glass of milk or two slices of cheese) significantly inhibit iron absorption. Polyphenols and phytates should be consumed separately from iron rich meals and/or with vitamin C and carotenoids (vegetable pigments in bright non-green and some dark green vegetables) which can reduce their impact on iron absorption. The fact that removing key polyphenols from the diet can have little impact on iron status would indicate that other factors in the diet can almost completely counteract them, with vitamin C and carotenoids being the logical candidates. No similar findings have been made for phytates. Alcohol consumption reverses the impact of iron levels on the genes regulating the key hormone, hepcidin, generally leading to increased absorption of iron and lead as the body reacts to adequate iron levels as if iron deficient.

Phytates, which are the strongest iron inhibitors (reducing absorption by up to 90%), also inhibit calcium and zinc absorption by up to approximately two-thirds while reducing magnesium absorption by somewhat less. Haeme iron, found in meat and fish (particularly red meat), is more easily absorbed (approximately 15-40% as compared to 1-15%) and is only significantly inhibited by large quantities of dairy products, while fish and meat proteins enhance non-haeme iron absorption.

Because the body tightly regulates iron absorption, rapid changes in iron status should not be expected, and as iron status improves from deficiency, measurable iron levels (serum ferritin) may initially decline as iron storage is not the body’s highest priority. Those considering taking iron supplements, unless severely deficient, may wish to consume them on an other than daily basis (generally twice the daily amount bi-weekly) since it reduces the risk of side effects, impacts on other nutrients and impaired absorption of non-haeme iron.

It should be noted there are a range of medical reasons for iron deficiency, so medical advice should always be sought.

For more information, see the relevant fact sheet or the longer article in our newsletter, Lead Action News, Volume 9, number 3.

1. Are You Getting Enough Iron [including Vegetarian Sources of Iron and the 2006 revised Nutrient Reference Values], Sanitarium, updated on 8/7/09 by Michelle Reid, Dietitian, Sanitarium www.lead.org.au/fs/SANITARIUM_Are_you_getting_enough_iron_20090708.pdf

2. Fact Sheet - Iron Nutrition and Lead Toxicity Taylor, Robert www.lead.org.au/fs/Iron_Nutrition_&_Lead_Toxicity_Fact_Sheet_20090630.pdf

3. Relationships of Lead, Copper, Zinc, and Cadmium Levels versus Hematopoiesis and Iron Parameters in Healthy Adolescents Jong Weon Choi and Soon Ki Kim Annals of Clinical & Laboratory Science 35:428-434 (2005) www.annclinlabsci.org/cgi/reprint/35/4/428 [Found a significant relationship between blood lead levels and iron status even in individuals without iron deficiency]

4. 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 [Finds that children with anemia, including lead induced anemia, are likely to have lower iron levels]

5. Protective Value of Dietary Copper and Iron against Some Toxic Effects of Lead in Rats David S. Klauder and Harold G. Petering Environmental Health Perspectives Vol. 12, pp. 77-80, 1975 www.ncbi.nlm.nih.gov/pmc/articles/PMC1475026/pdf/envhper00496-0079.pdf [A dated but interesting article that found that iron in combination with copper (now known to be essential in iron transport) could modify lead-induced anemia and protect the kidneys]