General Description
Copper is a metallic trace mineral essential in human nutrition.
A versatile mineral involved in numerous biological functions, copper
is most concentrated in brain and liver tissues, but significant
amounts are also found in muscle, bone, and skin tissues. Over 90%
of the body's circulating copper is found in ceruloplasmin, a plasma
protein instrumental in iron absorption. Copper is a key component
of many vital enzymes, most notably lysyl oxidase (an enzyme involved
in the formation of collagen structures) and the antioxidant enzyme
superoxide dismutase. Supplemental copper is found in many forms
(e.g. sulfate, gluconate, picolinate) and is commonly included in
multi-vitamin/mineral formulas.
Food sources
Copper is found in a wide variety of foods, with the richest sources
being oysters and other shellfish. Nuts, legumes, mushrooms, whole
grains, and meats are also good sources. Because it is commonly
used in plumbing, significant amounts of copper are often present
in tap water.
Health applications
- Antioxidant protection
- Bone
strength
- Cardiovascular health
- Inflammation
Deficiency symptoms
Because copper is found in many foods, and the body requires only
small amounts, overt deficiencies are rare. Copper deficiencies
have been observed in people supplementing large amounts of zinc,1-3
in premature infants on diets low in copper,4
in patients on long-term intravenous feeding without copper supplementation,
and in people with Menke's syndrome (a hereditary disorder that
impairs copper absorption).5 The most common
symptoms of copper deficiency are anemia and decreased white blood
cell concentrations.5 Copper depletion has
also been associated with ischemic heart disease, hypertension,
abnormal lipid metabolism, rheumatoid arthritis, and osteoporosis.6-12
Cardiovascular health
Copper's role in cardiovascular health is still unclear, with
various studies showing both positive and negative associations.
Copper is an essential component of superoxide dismutase (SOD),
an antioxidant enzyme that provides vital protection for the vascular
system. Studies have linked low copper and high zinc intakes to
increased risk for ischemic heart disease and high blood pressure,6,8,9
and high zinc-to-copper ratios have been observed in hair samples
taken from heart attack survivors.13 However,
high serum copper concentrations are commonly observed in heart
disease patients, and have been linked to increased risk for coronary
heart disease and cardiac mortality.14 It
appears that adequate copper intake is important for cardiovascular
function, but excess copper may have a harmful effect.
Inflammation
Superoxide dismutase and other copper-dependent enzymes are known
to have antiinflammatory activity, and changes in copper metabolism
are commonly seen in acute and chronic inflammatory conditions.15-18
Research has demonstrated that copper complexes of inactive substances
exert antiinflammatory activity and that some nonsteroidal antiinflammatory
drugs (NSAIDs) are more effective when combined with copper.19
Copper bracelets have long been used as a folk remedy for arthritic
conditions, but there is little scientific evidence to support
this practice.
Dosage/toxicity
The reference daily intake (RDI) for copper is 2 mg, which most
people consume in their regular diet. Vitamin C and zinc interfere
with copper absorption, thus people supplementing their diets
with these nutrients should also include copper. Because most
excess copper is excreted, copper toxicity is rare, occurring
mostly in people with Wilson's disease. Copper
intake above 10 mg per day may cause nausea. Because it inhibits
zinc absorption, copper intake above 3 mg per day is generally
not recommended. |
