Too much magnesium may cause diarrhea and abdominal cramps. In severe cases, it can lead to difficulty breathing, irregular heartbeat, and death. Severe magnesium toxicity is not all that common.

A 2022 study found that magnesium L-threonate improves memory, learning, cognitive abilities, and recall. Magnesium L-threonate can cross the blood-brain barrier, which may explain its ability to ...