1. Formation of connective tissues: Copper helps in the formation of connective tissues, including bone, cartilage, and tendons. It also plays a role in the maintenance of the structure of blood vessels and the heart.
2. Energy production: Copper is involved in the production of adenosine triphosphate (ATP), which is the primary source of energy in the body. It helps in the metabolism of carbohydrates, proteins, and fats.
3. Functioning of the nervous system: Copper is involved in the functioning of the nervous system. It helps in the transmission of nerve impulses and the production of neurotransmitters, which are chemicals that transmit signals between nerve cells.
4. Immune system function: Copper is important for the functioning of the immune system. It helps in the production of white blood cells, which are involved in fighting infections and diseases.
5. Synthesis of red blood cells: Copper is involved in the metabolism of iron, which is necessary for the synthesis of red blood cells. It also helps in the transport of iron in the body.
6. Production of melanin: Copper is involved in the production of melanin, a pigment that gives color to the skin, hair, and eyes.

1. Shellfish: Oysters, squid, and lobster are excellent sources of copper.
2. Nuts and seeds: Almonds, cashews, sesame seeds, and pumpkin seeds are good sources of copper.
3. Whole grains: Brown rice, wheat bran, and oatmeal are good sources of copper.
4. Organ meats: Liver, kidney, and heart are good sources of copper.
5. Dark chocolate: Dark chocolate is a good source of copper.

Copper deficiency is rare in healthy individuals as the daily requirement for copper can be met through a balanced diet. However, it can occur in individuals who have gastrointestinal diseases such as celiac disease, Crohn’s disease, or other malabsorption syndromes, as copper absorption takes place in the small intestine. Copper deficiency can also occur in individuals who receive parenteral nutrition without copper supplementation.

Symptoms of copper deficiency include anemia, fatigue, weakness, decreased immunity, impaired growth, bone abnormalities and neurological disorders, with symptoms such as numbness and tingling in the extremities.

In infants, copper deficiency can cause hypotonia, anemia, and poor growth.

Copper deficiency can also lead to a rare condition called Menkes disease, which is characterized by poor absorption and transport of copper, resulting in neurological problems and abnormal hair growth.

If left untreated, copper deficiency can lead to more severe complications, including neurologic damage and immune dysfunction.