 Magnesium is an essential micronutrient found in a wide variety of foods yet the US Department of Agriculture estimates that only about half of the population gets enough of it in their diets. How essential is it? Magnesium is found in every single cell in the body, with the highest concentrations in the bones and teeth, followed by the brain, heart and blood. It is involved in 300 separate metabolic functions. Because relatively little of the body's magnesium circulates in the blood, however, it can be hard to test magnesium levels directly. Instead, people and their doctors need to be on the alert for the early warning signs of deficiency. Symptoms to watch for What exactly does magnesium do in the body? In a nutshell: a little of everything. It is required for the production of energy by the body, along with DNA, RNA, protein and fat. It helps maintain blood vessels dilated at appropriate levels for heart health, and helps maintain oral and immune health. Magnesium also plays a key role in maintaining the electrolyte balance of cells, which means it critically affects nerve signals, muscle contractions and heartbeat. In its early phases, magnesium deficiency leads to digestive symptoms such as loss of appetite, nausea and vomiting. It also causes weakness and fatigue. Early magnesium deficiency has also been linked with sleep disturbances, including insomnia, and mood disturbances such as anxiety and depression. If the problem is not addressed in its early phases, deficiency will likely worsen. Ongoing, low-grade deficiency may lead to chronic health problems including osteoporosis, heart disease and diabetes. Low levels of magnesium in the brain have been linked to the tremors associated with Parkinson's disease. More severe deficiency produces numbness and tingling, along with muscle dysfunction including twitches, cramps, seizures, abnormal heart rhythm and spasms, and even difficulty breathing. It can also produce personality changes. The groups at highest risk of magnesium deficiency are the elderly, diabetics, people who take diuretics and women who use hormonal birth control. Preventing or correcting deficiency How can you protect yourself from magnesium deficiency, or start correcting it if you worry your levels may be too low? If your deficiency is not severe, the best place to start is always by improving your diet. Magnesium is found in a wide variety of foods including beans, whole grains, leafy green vegetables, avocados, and seeds and nuts. Unfortunately, these foods are typically not consumed enough in the Western diet. Magnesium is also found in dark chocolate. For context, just 1 ounce of dry, roasted almonds or cashews or a half cup of spinach contains 20 percent of your daily magnesium requirement. You can get 15 percent of your daily magnesium from 1 cup of soy milk or a half cup of black beans. One cup of avocado, a 3.5 ounce baked potato (with skin), a half cup of brown rice, 1 cup of low-fat yogurt, and a single serving of fortified breakfast cereal all provide 10 percent of your daily magnesium needs. Magnesium is best absorbed by the body when it is consumed along with calcium and vitamin B6. You should aim to consume between 500 and 1,000 mg of magnesium daily. If you do choose to take a magnesium supplement, look for one that also includes these nutrients . You can also boost your body's effective use of magnesium by taking a supplement that also includes the magnesium co-factors glycinate, malate, orotate and taurinate. These increase your body's absorption of magnesium, while optimizing magnesium's effects on your heart, muscles, mood and general bodily systems. Magnesium glycinate is the form most effective at helping to correct long-term deficiency. 