Thu, May-11-06, 14:57
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Registered Member
Posts: 1,770
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Plan: CRON / Zone
Stats: 118/110/110
BF:very low
Progress: 100%
Location: Cardiff
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Heres something interesting for you to read
Quote:
Zinc and copper are essential minerals critical to health and commonly deficient in Western diets. An ongoing study tracking the nutritional intake of Americans found that 75% of older American adults were found to be failing to reach the RDA for zinc, and none of them achieved even the minimum recommended intake for copper. Yet while the importance of zinc is widely recognized, copper’s crucial role in our health has often been discounted. An overemphasis on zinc has resulted in widespread, unbalanced zinc supplementation. And that has serious implications for your long-term health.
Zinc and copper are so similar in their atomic structure that they can actually compete with one another, not only for absorption, but also for utilization in the body’s biochemical pathways. When your intake of zinc is too high relative to your copper intake, the excess zinc actually interferes with the activity of enzymes, which depend on copper for their biological function, by stepping in to copper’s proper binding sites in the enzymes. When copper is not properly incorporated into these enzymes, they can’t fulfill their biochemical duties.
A high intake of zinc, without a balancing increase in copper intake, can therefore lead to a secondary, functional copper deficiency by competing for absorption and interfering with its metabolism. Research suggests that an excessive ratio of zinc to copper has a negative impact on cardiovascular and skeletal health.
Both animal and human evidence suggests that, for optimal utilization of both minerals, the balance between zinc and copper should be about ten-to-one. But it’s common for supplements containing these nutrients to include too much zinc, and little or no copper, with the result that many – perhaps most – zinc supplements and multivitamin multivitamin and multimineral formulas contain potentially harmful zinc imbalances.
This isn’t just a theoretical concern. In a series of human studies, putting volunteers on a diet and supplement regimen in which the ratio between zinc and copper was 23.5-to-one (and sometimes lower) – common zinc-to-copper ratios, found in many multivitamins on health food store shelves – resulted in wide-ranging metabolic disturbances, including reduced levels of the copper-based antioxidants enzymes cytosolic superoxide dismutase and ceruloplasmin, increased total and LDL (“bad”) cholesterol, anemia, reductions in the body’s levels of enkephalins (natural pain-killing molecules), and cardiac dysfunction (including rhythm disturbances and even heart attacks!).
At the extreme, out-of control zinc supplementation impairs immune function, despite the fact that an adequate intake of zinc is necessary for normal immune function. This is especially galling, considering that the most common reason for zinc supplementation is to support healthy immunity. One reason for this may be copper’s important role in immune function: one of the classic signs of ‘simple’ copper deficiency is depressed levels of important white blood cells (leukocytes and neutrophils).
Over the long term, it seems that other problems linked to long-term, subclinical ‘simple’ copper deficiency – such as impaired bone metabolism, poor glucose metabolism, arthritis, neurological dysfunction, and increased levels of Advanced Glycation Endproducts (AGE) – would also manifest from a functional copper deficiency created by excessive zinc intake, leading top copper researcher Dr. Leslie M. Klevay to warn of the “hazards of zinc supplements.” The problem, of course, is not zinc supplements – but excessive or unbalanced zinc supplementation.
Excessive Zinc and Prostate Health
The most ironic twist in the tale of overemphasis on zinc has only recently appeared. Many men take zinc supplements to support the health of their prostates, because the prostate has the highest levels of this mineral of any organ of the body, and most studies have found that low levels of zinc in the prostate are associated with benign prostatic hypertrophy (BPH) and prostate cancer. But a large new study, which tracked the health habits of nearly 50 000 American male health professionals for 14 years, found that extreme zinc oversupplementation is associated with a more than doubled risk of developing prostate cancer, especially if continued for more than 10 years.
This doesn’t mean that men concerned about prostate health should stop making sure that their zinc intake is adequate: there was no association of zinc supplement use and prostate cancer in men with more reasonable intakes of the mineral. But it does mean that the targets that we should aim for are the kinds of intakes typical of a healthy diet – meaning a supplement designed for sustainable, long-term use should not contain more than about 11 milligrams of zinc.
Copper, Free Radicals, and Heart Health
Aside from an overemphasis on the benefits of zinc and a mysterious tendency to ignore copper’s benefits, much of the reason for unbalanced zinc supplementation has come from the myth that copper is a ‘pro-oxidant’ mineral, which might accelerate free radical damage in the body. The reason for this concern is the so-called Fenton reaction, whereby “transition metals” (such as iron and copper), when present in their free, ionic form, can catalytically convert the mildly-dangerous hydrogen peroxide into the vicious hydroxyl radical.
But while copper ions can trigger the Fenton reaction in the artificial conditions of the test tube, it’s a non-issue from a health perspective – because the body just doesn’t contain enough free, ionic copper to be of concern. Test-tube studies showing that ionic copper can accelerate the oxidation of LDL (‘bad’) cholesterol, for instance, have used copper ion concentrations that are literally millions of times as high as are found in the body. In fact, controlled human studies have shown that even at high intakes (up to 7 milligrams a day), copper supplements don’t increase free radical damage in the body, but actually tend to decrease it, probably because of the nutrient’s indispensable role in the body’ antioxidant defenses.
Zinc and copper are both key minerals. You need both minerals – and you need them in balance.
References
Sandstead HH. Requirements and toxicity of essential trace elements, illustrated by zinc and copper. Am J Clin Nutr. 1995 Mar; 61(3 Suppl): 621S-624S.
Klevay LM. Lack of a recommended dietary allowance for copper may be hazardous to your health. J Am Coll Nutr. 1998 Aug; 17(4): 322-6.
Allen GD, Klevay LM. Copper: an antioxidant nutrient for cardiovascular health. Curr Opin Lipidol. 1994 Feb; 5(1): 22-8.
Leitzmann MF, Stampfer MJ, Wu K, Colditz GA, Willett WC, Giovannucci EL. Zinc supplement use and risk of prostate cancer. J Natl Cancer Inst. 2003 Jul 2; 95(13): 1004-7.
Lowe NM, Lowe NM, Fraser WD, Jackson MJ. Is there a potential therapeutic value of copper and zinc for osteoporosis? Proc Nutr Soc. 2002 May; 61(2): 181-5.
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Zinc Supplements
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