Magnesium deficiency in humans has several early symptoms, including fatigue, lack of appetite, confusion, irritability and muscle twitching, according to MedlinePlus. Severe deficiency can cause hallucinations, delirium, tingling and numbness.
Many of the early symptoms of magnesium deficiency are psychological symptoms, including irritability, a reduced ability to learn and poor memory, according to MedlinePlus. People with low magnesium levels can also experience insomnia and a loss of appetite, which can eventually lead to anorexia. If the deficiency worsens, the patient may experience moderate deficiency symptoms, such as a rapid heart rate. In severe cases of magnesium deficiency, the muscles may contract continually.
The recommends magnesium intake is 400 to 420 milligrams per day for men and 310 to 320 milligrams per day for women, according to MedlinePlus. The recommendations for children gradually increase from 80 milligrams at 1 year old to between 360 and 410 milligrams for teenagers. Magnesium requirements are greater during pregnancy. Magnesium deficiency is rare, but it can occur in people who abuse alcohol or who have problems absorbing magnesium from food. Eating dark green, leafy vegetables can help individuals get enough magnesium, although it is also found in other fruits, vegetables, nuts, soy products and beans.