Magnesium critical for 300 biochemical reactions in the body SANTA MONICA, Calif., Oct. 16 (UPI) -- Magnesium is the fourth-most abundant mineral in the body -- half is in the bones -- yet many, especially seniors, do not get enough, a U.S. food expert says. "Magnesium is critical because it is needed for over 300 biochemical reactions in the body," Phil Lempert, a food industry analyst, trend watcher and creator of supermarketguru.com, said in a statement. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, supports a healthy immune system, keeps bones strong, as well as helping regulate blood sugar levels, promotes normal blood pressure and is known to be involved in energy metabolism and protein synthesis. In more functional terms, magnesium is beneficial for stress relief, staying regular, women's health, energy, sleep, cardiovascular health and more, Lempert said. National Health and Nutrition Examination Surveys in 1999-2000 and 1988-94 suggested older adults have lower dietary intakes of magnesium than younger adults. In addition, magnesium absorption decreases and renal excretion of magnesium increases in older adults. Seniors are also more likely to be taking drugs that interact with magnesium. Symptoms related to inadequate magnesium can include low energy, muscle tension, headaches, irritability, inability to sleep, abnormal heart rhythms and anxiety/nervousness. Foods high in magnesium include whole grains, legumes, green vegetables, dark-green leafy vegetables, pumpkin seeds, spinach, Swiss chard, soy beans, sesame seeds, black beans, flax seeds, buckwheat, kidney beans and chocolate.