1. What is it and where does it come from?

Iron is the most abundant element on Earth and is an essential trace mineral for humans. It can be found in many different foods including meats and vegetables as well as be obtained by using iron cookware.

In supplements iron comes in many forms with the best absorbed being ferrous succinate or sulfate although ferrous sulfate can cause gut irritation. A good alternative is ferrous gluconate and ferrous fumurate. Also available is a hydrolyzed protein chelate form called ferritin. In the body iron is stored primarily in bone marrow, the spleen, and the liver.

2. What does it do and what scientific studies give evidence to support this?

Iron is best known for its role as oxygen carrier within the protein hemoglobin. Red blood cells contain hemoglobin which transport oxygen to various tissues as it passes through the longs thanks to the oxygen binding characteristic of iron.

Myoglobin, another molecule containing iron, carries and stores oxygen in cells and is essential for all bodily tissues and their cellular activity. Every 120 days, red blood cells and the iron they contain are replaced and recycled.

Numerous enzymes involved in metabolism require iron to function. Iron is necessary for protein metabolism as well as cell division and growth because of its role in DNA synthesis. Iron also plays a role in connective tissue production, neurotransmitters, immune system maintenance, and in the production of thyroid hormone.

Only about 5-10 percent of the iron in our diets is absorbed. Hem-iron (organic iron found in meats) is absorbed much better than "non heme". Sugars and amino acids may boost absorption.

Female athletes, endurance athletes, and athletes on low-calorie diets are at a heightened risk for deficiency. Iron deficiency is also considered one of the most common nutritional deficiencies in the US. Deficiency symptoms include fatigue, rapid heartbeat, breathlessness, lack of concentration, giddiness, disturbed sleep, sever menstrual pain and bleeding, cracked lips and eye inflammation.

Iron's RDA for men is 10 mg and for women is 15mg. However, for hard training athletes the PDI (performance daily intake) for men and women is from 25 to 60 milligrams.

The estimated safe range for adults is 80mg but taking as little as 30mg every day over a long period of time has been known to lead to overdose symptoms. Excessive intake can cause abdominal cramping, diarrhea, constipation, nausea, deterioration of the gut lining and liver damage.

The easiest way to eat your serving of iron is with 1 cup of Branflakes which will provide 10.8mg. Other than that, red meat, liver, fish, and poultry are the some of the best sources, providing the preferable "heme-iron". Shellfish and eggs as well as legumes and a few different dark green vegetables are mediocre sources.

Cooking foods in an iron pan can "fortify" them with a type of iron that has a fairly low bioavailability. The best supplements for iron include liver tabs as they provide the well absorbed heme-iron.