Like may micro-minerals, manganese has a broad range of functions. It is essential for activating enzyme systems involved in the synthesis of cartilage. It is also a constituent of certain enzymes involved in the protection of tissues from free radical damage. Manganese is necessary to both thyroid hormone and sex hormone production, and is important in manufacturing cholesterol and insulin. It is also needed for storing glucose in the liver and for healthy bone growth.

Manganese deficiency reduces fertility as well as white blood cell count. Prolonged deficiencies result in breakdowns of the organ and immune system. Manganese is mostly found in sea- and freshwater algae, and fruits and vegetables.