Magnesium orotate is a complex of magnesium plus orotic acid. Some people use it for its magnesium content (to prevent or treat magnesium deficiency) while others take it for its orotic acid, which is used for improving athletic performance and endurance, and for heart health.
In fact, magnesium orotate probably isn't the best choice as a magnesium supplement for preventing or treating magnesium deficiency because it doesn't appear to offer an advantage over others and it can cost up to 9 times more than other magnesium products. To get, for example, 200 mg of magnesium from magnesium orotate supplements you might spend 10 to 18 cents. In contrast, you can get the same amount of magnesium for as little as 2 cents, as shown in ConsumerLab.com's Magnesium Supplements Review.
Magnesium orotate might have a protective role in heart disease. A preliminary clinical study in people with heart failure found that giving 6,000 mg of magnesium orotate daily for one month, followed by 3,000 mg daily for 11 months reduced the risk of dying during the study by about 25%. It also improved heart failure symptoms in about 40% of patients (Stepura, Int J Cardiol 2009). Preliminary research in animals and humans suggests that this protective role of magnesium orotate may relate to its involvement in the synthesis of genetic material such as RNA and DNA (Rosenfeldt, Cardiovasc Drugs Ther 1998).
Although magnesium orotate is often promoted and used to improve athletic performance or endurance, there is no reliable evidence that it works for this purpose.
Some concerns about the safety of orotic acid from supplements such as magnesium orotate have been raised. Research in animals shows that doses of 100 mg/kg/day or more of orotic acid have tumor promoting effects in experimental tumors. Lower doses of 50 mg/kg/day did not have this effect (Laconi, Carcinogenesis 1993, Laconi, Carcinogenesis 1993, Laconi, Carcinogenesis 1988). Based on these data, a panel of the European Food Safety Authority (EFSA) concluded that orotic acid-containing products, such as magnesium orotate, represent a safety concern when used in amounts of 100 mg/kg or more daily (e.g., 7,000 mg for a 70 kg [154 lb] adult) (EFSA Journal 2009).
The bottom line:
Magnesium orotate is not the best choice as a magnesium supplement and despite preliminary evidence of a benefit for people with heart disease, there is also evidence suggesting a potential safety concern at around the high dosage used for that purpose. Until more is known about the potential benefits and risks, it may be best not to use magnesium orotate.