Magnesium is an essential mineral nutrient for human life. Magnesium ions are essential to all living cells, but nearly 50% is found within the bones where they play a major role in bone and mineral homeostasis. Magnesium is also important for many cellular reactions such as energy generation, cell membrane stabilization and protein activation. Food sources of magnesium include green leafy vegetables, nuts, meat, starches and milk. Intestinal absorption of dietary magnesium in a typical diet is approximately 50 percent 1.
The U.S. Food and Drug Administration (FDA) has established a Reference Daily Intake (RDI) of 400 mg magnesium for adults and children 4 or more years of age (21CFR101.9). RDIs are a set of dietary references for essential vitamins and minerals that are considered amounts sufficient to meet the daily requirements of healthy individuals. RDIs serve as the basis for calculating the percent daily value (%DV) amounts found on dietary supplement and food labels.
Magnesium, when ingested as a naturally occurring substance in foods, has not been demonstrated to exert any adverse effects. However, adverse effects, such as mild gastrointestinal disturbances, have been observed with excess magnesium intake from nonfood sources 1.
Magnesium oxide, or magnesia, is a white mineral powder used as a source of magnesium in dietary supplements. It is also used as an excipient in oral formulations to bind excess water and to modify the pH (acidity or alkalinity) 2. Magnesium oxide is considered generally recognized as safe (GRAS) for use in foods by the U.S. Food and Drug Administration (FDA) (21CFR184.1431) 3.
Magnesium glycinate is a form of chelated magnesium, in which the magnesium ion is bound to the amino acid glycine. Magnesium glycinate is more easily absorbed through the intestines into the blood stream than other sources of magnesium (e.g. magnesium oxide) 4. Due its enhanced bioavailability, magnesium glycinate is gaining popularity for use as a magnesium source in dietary supplements.
Magnesium citrate is a chelated form of magnesium, in which the magnesium ion is bound to citric acid. It is used as a source of magnesium in dietary supplements 5.