One of the most abundant metals on earth, iron, is also very essential to proper human functioning. Women in particular need to ensure that they are meeting their iron requirements, as some will be lost each month in the blood during menstruation.

The main role that iron plays in the body is to help form the proteins and enzymes required for health. It works with the cells to help transport oxygen in the blood and for regulating cell growth and differentiation (specifying which cells develop into which types).

When you are low in this nutrient, the most commonly felt symptom is fatigue and poor muscular performance. For this reason, athletes in particular also need to ensure their needs are being met. Unfortunately, since so many athletes diet to achieve a desirable body weight composition, they end up cutting out some of the foods that are highest in this valuable mineral.

The best sources for this nutrient are red meat, because it's absorbed the best from this type of food product. You can also get it from fish, poultry, lentils and beans however it will be the nonheme type, which isn't quite as good. Additionally, you can take it in supplemental form however again, it's still not quite the same as if you were getting the heme version found in animal products.

The recommended daily intake is set for 18 mg per day for females and 8 mg per day for males. Additionally, when you are taking in more than you need, your body will reduce its ability to absorb it so you don't particularly have to worry all that much about toxicity.